![Meflowrate [M3/S] 0,02 0,02 0,02 0,02 Avtotalpressure [Pa] 1042610,71 1067482,10 958725,13 1155812,86 Avtemperature (Fluid) [K] 239,15 236,77 231,99 240,43](http://data.docslib.org/img/db1ed0ae2b123ea417a2bdd2fc19b3ec-1.webp)
CONTENTS Nr.1/2017 Pag.
1. Senai YALCINKAYA - CORROSION AND SURFACE PROTECTION IN MACHINE MATERIALS FRICTION HAVE DIFFERENT SURFACE PAIRS EXPERIMENTAL INVESTIGATION OF FACTORS 3 2. Stefan GHIMISI - ANALYSIS OF POINT CONTACTS USING THE COMBINED BOUSSINESQ-CERRUTI PROBLEM 13 3. Liliana LUCA - STUDY OF A PROBLEM OF GRAPHIC ENGINEERING 19 4. Ion BULAC - THE INFLUENCE OF THE CONSTRUCTIVE PARAMETERS ON THE VIBRATION INHERENT FREQUENCIES AT BENDING FROM TWO-SHAFTS TRANSMISSION 26 5. Minodora PASĂRE - PRACTICAL METHOD FOR DETERMINING THE DYNAMIC COEFFICIENT 31 6. Gheorghe DRĂGUŢ - CONTRIBUTIONS TO THE DYNAMIC ANALYSIS OF THE TORQUE TORSION TORQUE OF MECHANICAL TRANSMISSIONS WITH WHEEL WRENCHES 36 7. Răzvan Bogdan ITU, Vilhelm ITU - ANALYSIS OF COMPENSATING CABLE CONNECTING DEVICES FOR WINDING INSTALLATION VESSELS 44 8. Răzvan Bogdan ITU, Vilhelm ITU - DIAGNOSIS OF THE WINDING MACHINE IN THE OLD SHAFT WITH SKIP IN LONEA MINING PLANT 51 9. Marius STAN - OPERATING THE OIL PRODUCTION FACILITY WITH SOLAR AND WIND GENERATOR 60 10. Marius STAN - MODELLING OF THE GAS DIFFUSION IN FLEXIBLE PIPELINES FOR OIL & GAS PRODUCTION 67 11. Alin STĂNCIOIU - THE FOURTH INDUSTRIAL REVOLUTION „INDUSTRY 4.0‖ 74 12. Constanţa RĂDULESCU, Marius Liviu CÎRŢÎNĂ - ASPECTS CONCERNING THE IMPLEMENTATION OF A METHODOLOGY FOR DETERMINING THE COLUMNS DIAMETERS OF GUIDING A PRESE - (Part I) 79 13. Constanţa RĂDULESCU - ASPECTS CONCERNING THE IMPLEMENTATION OF A METHODOLOGY FOR DETERMINING THE COLUMNS DIAMETERS OF GUIDING A PRESE - (Part II) 84 14. Florin CIOFU, Alin NIOAŢĂ - RESEARCH ON DEGRADATION CORROSIVE ENVIRONMENT OF SOME STEELS USED IN MANUFACTURING MINING EQUIPMENT. MECHANICAL TESTS 89 15. Florin CIOFU, Alin NIOAŢĂ - RESEARCH ON DEGRADATION CORROSIVE ENVIRONMENT OF SOME STEELS USED IN MANUFACTURING MINING EQUIPMENT. MICROSCOPIC ANALYSIS 96 16. Cătălina IANĂŞI - GLASS FIBERS – MODERN METHOD IN THE WOOD BEAMS REINFORCEMENT 102 17. Cristina IONICI - CONSIDERATIONS ON THE STRUCTURE OF SINTERIZED MATERIALS FOR AUTOLUBRIFICANT HYDRODYMNIC WASTE 108 18. Alin NIOAŢĂ, Florin CIOFU - PARAMETERS AND FACTORS OF PROCESSING THROUGH COMPLEX EROSION 113 19. Alin NIOAŢĂ, Florin CIOFU - PROCESSING OPERATIONS OF METALLIC CARBIDES THROUGH COMPLEX EROSION 119 20. Adrian Stere PARIS - A SHORT ANALYSIS OF THE OF THE SMARTPHONES RELIABILITY 126 21. Adrian Stere PARIS, Constantin TÂRCOLEA - QUALITY LOSS FUNCTION FOR MACHINING PROCESS ACCURACY 131 22. Dan SAVESCU - THE IMPORTANCE OF INTELLECTUAL PROPERTY PROTECTION IN TECHNOLOGICAL TRANSFER. SOME ASPECTS 135 23. Dan SAVESCU - ASPECTS ABOUT BUILDING MODELS IN INNOVATION 142 24. C. MIHAI, R. N. DOBRESCU, N. POPA - THE COROSION OF THE WELDED JOINTS ON METALAL PIPES 149 25. Оlеg KLЕNОV, Grygoriy NOVIKOV - EFFICIENT DIRECTIONS OF DEVELOPMENT OF METHODS OF MECHANICAL PROCESSING OF MATERIALS 156 26. Valentin SHKURUPY - INFLUENCE OF MACHINING ON QUALITY PARAMETERS OF OPTICAL METAL PRODUCTS 163 27. Monica BÂLDEA, Ancuţa BĂLTEANU, Mihaela ISTRATE - ON THE QUALITY CONTROL OF THE FUEL FILLER FLAP LINING MARK 171 28. Ancuţa BĂLTEANU, Monica BÂLDEA - IMPROVEMENT FOR AN ASSEMBLY FLOW FOR A GIVEN COMPONENT (1) 178 29. Yaroslav GARASHCHENKO - EVALUATION OF GEOMETRICAL COMPLEXITY OF PRODUCTS BASED ON THE ANALYSIS OF TRIANGULATED MODELS 184 1 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
30. Cătălin IANCU - ABOUT FEATURES OF SIMULATION MODULE IN SOLIDWORKS 191 31. Cătălin IANCU - ABOUT OPTIMIZATION DESIGN STUDY ON SOLIDWORKS 199 32. Oana CHIVU, , Claudiu BABIS, Andrei DIMITRESCU, Dan Florin NIŢOI - THE DETERMINATION AND APPRECIATION OF PROFESSIONAL MICROCLIMATE AT A WORKPLACE 206 33. Oana CHIVU, , Claudiu BABIS, Andrei DIMITRESCU - THE DETERMINATION AND APPRECIATION OF OCCUPATIONAL TOXICITY AT WORK 214 34. Andrei DIMITRESCU, Claudiu BABIS, Oana CHIVU - FACTOR ANALYSIS OF QUALITY CHARACTERISTICS 222 35. Andrei DIMITRESCU, Claudiu BABIS, Oana CHIVU - METHOD OF ANALYSIS OF VALUE OF USE 228 36. Nicoleta-Maria MIHUT - DETERMINING THE RAISONAL LIMITS OF THE TISMANA CAREER AND ITS MAXIMUM ECONOMIC DEPTH 235 37. Ramona Violeta CAZALBAȘU, Camelia CĂPĂŢÎNĂ - STUDIES ON WASTE MANAGEMENT IN PESTISANI COMMUNE, GORJ COUNTY 239 38. Ramona Violeta CAZALBAŞU, Camelia CĂPĂŢÎNĂ, Cîrţînă DANIELA - STUDY ON WATER QUALITY INDICATORS AT TAIA TREATMENT PLANT HUNDEDOARA COUNTY 243 39. Liliana LUCA, Minodora Pasare, Alin STANCIOIU - STUDY TO DETERMINE A NEW MODEL OF THE ISHIKAWA DIAGRAM FOR QUALITY IMPROVEMENT 249 40. Delia NICA BADEA - EMISSION IMPACT ASSESSMENT FROM TURCENI POWER PLANT ON THE HEAVY METAL POLLUTION OF THE SOIL 255 41. Ramona PECINGINĂ - STUDY ON THE BATS SPECIES IN THE CAVES PROTECTED NATURAL OF NORTH WEST GORJ 262 42. Irina Ramona PECINGINĂ, Roxana Gabriela POPA - FOOD BIOTECHNOLOGY - SUSTAINABLE DEVELOPMENT STRATEGY 269 43. Asterios KOSMARAS, Dimitrios TZETZIS - OXYGEN PRESSURE REGULATOR DESIGN AND ANALYSIS THROUGH FINITE ELEMENT MODELING 274 44. Feodor NOVIKOV, Vladimir POLYANSKY, Yury GUTSALENKO, Vladislav IVKIN - ANALYTICAL DETERMINATION OF CONDITIONS FOR PRODUCTIVITY IMPROVEMENT OF DIAMOND GRINDING 280
45. Roman PROTASOV, Sergey ANDRIENKO, Alexander USTINENKO, Alexey BONDARENKO, Nicholay MATUSHENKO - GEOMETRY MODELING OF GEAR AND CHAIN DRIVE WITH EVOLUTE PROFILE AND RESEARCH OF ITS CONTACT STRESS 287 46. Igor RYABENKOV, Yury GUTSALENKO, Cătălin IANCU, Feodor NOVIKOV - ANALYTICAL DETERMINATION OF CONDITIONS FOR SURFACE ROUGHNESS REDUCTION IN DIAMOND GRINDING 294 47. Mădălina Roxana BUNECI - A GROUPOID FRAMEWORK FOR STUDY ASYMPTOTIC BEHAVIOR OF A DISCRETE SYSTEM 301 48. Iuliana Carmen BĂRBĂCIORU- CARDINALITY AND ENTROPY FORINTUITIONISTIC FUZZY SETS 308 49. Constantin POPESCU, Gabi ROȘCA-FÂRTAT, Nicolae PANĂ - DETAILS OF OPERATIONS PERFORMED BY THE REMOTE CONTROL ROBOT (CONCEPT) TO THE HORIZONTAL FUEL CHANNEL DURING DECOMMISSIONING PHASE OF NUCLEAR REACTOR CALANDRIA STRUCTURE. PART I: OUTSIDE OPERATIONS 316 50. Constantin POPESCU, Gabi ROȘCA-FÂRTAT, Nicolae PANĂ - DETAILS OF OPERATIONS PERFORMED BY THE REMOTE CONTROL ROBOT (CONCEPT) TO THE HORIZONTAL FUEL CHANNEL DURING DECOMMISSIONING PHASE OF NUCLEAR REACTOR CALANDRIA STRUCTURE. PART II: INSIDE OPERATIONS 324 51. Tudor BURLAN-ROTAR, Gabriel Dumitru, Alina Ioana PRELIPCEANU - CONSIDERATIONS ON CONTACTLESS ELECTROMAGNETIC MEASUREMENT OF HUMIDITY IN PEDOLOGY 332 52. Tudor BURLAN-ROTAR, Gabriel Dumitru, Alina Ioana PRELIPCEANU - CONSIDERATIONS ON CONTACTLESS MEASUREMENTS IN HYDROGEOLOGY USING VERY LOW FREQUENCY 341 ELECTROMAGNETIC TECHNIQUES 53. Slavov STOYAN - A CONTERPORARYAPPROACH FOR OBTAINING REGULARLY SHAPED ROUGHNESS BY BALL-BURNISHING PROCESS CARIED OUT USINGCNC CONTROLEDMILLING MACHINES 349
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CORROSION AND SURFACE PROTECTION IN MACHINE MATERIALS FRICTION HAVE DIFFERENT SURFACE PAIRS EXPERIMENTAL INVESTIGATION OF FACTORS
Senai YALCINKAYA DepartmentofMechanical Engineering, Facultyof Technology,Marmara University,Kadikoy,34722Istanbul, Turkey,Tel: +905324727900 [email protected]
Abstract: Friction force, normal force, linear change. The normal force varies with the loads on the friction object. In order to determine the friction force and the friction coefficient, the friction object and the friction speed are used. The experimental work was carried out in three stages. In the first stage, the effect of normal force on the friction force was studied. In the second step, the friction force of the friction surface area is influenced. The effect of the change of the shear rate in step 3 on the friction force was investigated. At the last stage, the experimental study of the effect of the material selection on the friction force was made and it was seen that the aluminum / brass surface pair had the smallest friction coefficient as a result of the opening. The greatest coefficient of friction is found in the pair of glass / felt objects.
Key words: Friction coefficient, friction force, linear change, object surface pair
1. Introduction While in statics, we study idealized bodies excluding frictional forces, in the study of static and kinetic friction, we investigate realsolid bodies. Friction occurs in all solid bodies that are in contact and that are moved against each other. The cause of the occurringforces is, among other things, the surface roughness, which causes the surfaces to interlock.[1].Friction is defined as the resistance they exhibit against two materials movements that are in contact with each other and tend to make or move relative to each other. There is a counter force against the force which wants to bring the relative movement between the two bodies, which is defined as the friction force, which prevents movement between the contact surfaces of the bodies[2].If there is no relative movement between surfaces touching each other, static friction is mentioned. If the relative motion exists between the surfaces of two bodies, the friction in this case is called dynamic or kinetic friction. Friction force is not constant. The friction force depends on the coefficient of friction and the friction force changes with the change of this coefficient. Relative movement of objects moving relative to each other, in the sense that no lubricant is placed between the surfaces;
Fig. 1.The body adheres to its under-layer, FG weight, FH force of static friction, FN normal force,F external force, v velocity 3 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
Dry friction, liquid friction, and boundary friction between these two types of friction are investigated in three cases [3]. Static friction is present if displacing forces are actingon both bodies, but the bodies have not started to moverelative to each other yet. This is why we also talk aboutstatic friction that has to be overcome if we want to movea body. Static friction is a reaction force; in staticallydeterminate systems, it can be determined from theequilibrium conditions. (Figure 3 (c).)[3]. Dynamic friction occurs when a body moves along anotherand in contact with it, i.e. itactually rubs against it. Dynamicfriction increases with the roughnesses of the bodies‘ sur-faces and the pressure applied between the bodies. Thedynamic friction force is a physical force (active force) andproportional to the normal force FN.[1].
2. Experimental procedure Determination of friction coefficients with surface friction.When a object slides on another object, it applies a force parallel to the slip surface. This force is defined as the frictional force and reverses the relative motion of the objects [2]. The friction diagram of the friction system is shown in figure 1. Frictional force; Normal force, used material, depending on the surface properties of the material; the friction surface is not dependent on the surface area and the rate of materials shift.[4].
Fig. 2.FH force of static friction, FN normal force,F external force, v velocity
3. Materials used in the experiment
Felt, Plastic, Aluminum Plate, Brass plate, Glass plate, Wooden plate, Friction plate; Plastic, Glass and Aluminum Felt-covered brass, Felt Coated - Plastic, Felt-covered other materials
The experimental setup Small diameter cable winder, It was kept constant in all the experimental works and moved at the same speed. All experiments were carried out under the same conditions. The dry friction test setup is shown in Figure 2.
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Fig. 3. Dry friction test setup.
4. The shape of the friction test system The dry friction test system has a metal base and two guide beds (1) on it. The guide bearings are designed in accordance with the carrier (2). The arrangement includes a synchronous motor (12). This synchronous motor has a rotation speed of 10 rpm and rotates the cable winder (9). When the cable winder is connected to the other carrier and the motor is started, the cable is wound and therefore the carrier is moving. Two different cables, one 7.5 mm in diameter and the other 15 mm in diameter, can be used in order to allow the carrier to move at different speeds. The cable is removed from the carrier by manually opening it from the cable reel. In the test unit, friction plates (3) placed on the carrier; Made of aluminum, glass or plastic material.There is also a felt surface on the back of the plastic friction plate.Friction bodies (4) are made of aluminum or brass material. There is a felt surface on one side of boddy made from brass material and each of the friction objects is 1 Newton weight. In addition, there are 8 loads (5) each weighing 0, 5 N in the experimental setup. The friction force generated between the frictional object and the friction plate is measured by means of a dynamometer (6) when the motor is operated and the cable winder connected to the carrier attracts the carrier. The dynamometer has a measurement range of 2 N and sensitivity of 0.05 N. A damping cylinder (7) was placed in the dynamometer to suppress vibration on the dynamometer [3]. Dry friction test method is shown in Figure 3.
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Fig. 4. Schematic view of dry friction test setup.
5. Effect of Normal Force on Frictional Force Coulomb‘s law of friction states that the frictional force is proportional to the normal force. The proportionality factor μ depends on the materials pairing of the bodies and is called the coefficient of friction[1, 5]. FR = μ ・ FN (1)
Coulomb Law; Based on Coulomb‘s law, the friction force (FR), Normal force (Fn) shows a linear change. The normal force varies with the loads on the friction body. In order to determine the friction force and friction coefficient, Friction plate: Felt Friction body: Aluminum, smooth side (1 N) Friction speed: Small diameter cable winder is used.
Fig. 5. Schematic view of friction.
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Table 1. Change of friction force due to normal force Fs [N] 0,1 0,24 0,36 0,5 0,62 0,74 0,86 0,99 1,2
Fn [N] 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0
FR 0,100 0,160 0,180 0,200 0,207 0,211 0,215 0,220 0,240
Fig. 6.Normal force- dependent change of friction force
According to the graph shown in Fig. 6, the curve showing a change in the normal force of the friction force shows a linear change. When the normal force is equal to the subject weight, when we increase the weights added to the friction body, it is observed that the friction force also increases linearly.
6. Effect of Friction Surface Area on Frictional Force In order to determine the effect of the surface area on the frictional force, the experiment is carried out by placing the surfaces of the frictional small object (Ak) and large (Ab) in the form of rectangular prisms on the friction plate.In order to determine the friction force and friction coefficient. In experimental setup; Aluminum plate; Ab-large surface, Ak-Small surface. Friction plate: Aluminum Friction body: Aluminum, small and large surface areas on the smooth side (1 N) Friction speed: Small diameter cable winder is used. Table 2 shows the measured values of the effect of the friction surface area on the friction force[5].
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Table 2. Measured values of the effect of the friction surface area on the friction force.
Fs (Ak) [N] 0,17 0,26 0,30 0,42 0,54 0,57 0,65 0,70 0,81
Fs (Ab) [N] 0,43 0,53 0,67 0,78 0,99 1,18 1,29 1,42 1,79
Fn [N] 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0
FR= 0,170 0,173 0,150 0,168 0,180 0,163 0,163 0,156 0,162
FR= 0,430 0,353 0,335 0,312 0,330 0,337 0,323 0,316 0,358
Fig. 7. Effect graph of friction surface area on friction force. (Small surface area, large surface area).
There is a linear relationship between the normal force (Fa) and the frictional force (Fs) according to the graph in Figure 7. As can be seen from this graph, the frictional force developed when the friction surface area increases is increased. But this contradicts the theory that the change in surface area does not affect the friction force. It is believed that the change in surface area can be caused by the friction force changing because large and small surface areas do not have the same surface qualities. As the area of the friction surface increases, the effect on friction increases.
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7. Effect of change in shear rate on frictional force In order to determine the effect of shear rate on the friction force, small diameter (dk), the experiment was carried out by using cable wrappers of the other large diameter (dB), and carrying the carrier at different speeds.In order to determine the friction force and friction coefficient, Friction plate: Felt Friction body: Aluminum, rough side (1 N) Friction speed: Small and large diameter cable winders are used separately in each experiment.
Table 3. Effect of change in shear rate on friction force Fs (dk) [N] 0,38 0,59 0,77 0,97 1,16 1,30
Fs (db) [N] 0,36 0,65 0,81 1,02 1,21 1,46
Fn [N] 1,0 1,5 2,0 2,5 3,0 3,5
FR= 0,380 0,393 0,385 0,388 0,387 0,371
FR= 0,390 0,433 0,405 0,408 0,403 0,417
Fig. 8. Change in shear rate effect on frictional force. (Low shear rate, High shear rate)
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8. Effect of surface properties on friction force The rough and smooth side of the aluminum plate is placed on the friction plate to determine the effect of the surface properties on the friction force. In Table 1 and Table 3, the effects of aluminum friction on rough and smooth surfaces on friction were analyzed. In Table 1, the analysis of the smooth surface of aluminum showed that the friction force (Fs) at 3.5 N load was 0.74 N; the coefficient of friction (μ) was determined as 0.211. In the analysis made by placing the rough surface of aluminum in Table 3; Friction force (Fs) at 3.5 N load, 1, 46 N; the coefficient of friction (μ) was determined as 0,417. It is seen that the friction force and the friction coefficient on the rough surface are higher than the smooth surface.
9. Experimental investigation of effect of material selection on friction force Experiments have been carried out by changing the friction plate and friction material to determine the effect of different materials on the friction force.
Determination of friction between aluminum / brass surface pair In order to determine the friction force and friction coefficient, Friction plate: Aluminum Friction Body: Brass (1 N) Friction speed: Small diameter cable winder is used. Table 4. Friction between aluminum / brass surface pair object (μ=Fs/Fn). Fs [N] 0,17 0,46 0,63 1,13 1,08 1,31
Fn [N] 1,0 2,0 2,5 3,0 4,0 5,0
μ= 0,170 0,230 0,252 0,377 0,270 0,262
9.2. Determination of friction between glass / felt surface pair In order to determine the friction force and friction coefficient, Friction plate: Glass Friction Body: Felt-covered brass (1 N) Friction speed: Small diameter cable winder is used. Table 5. Friction between glass / felt surface pair(μ=Fs/Fn). Fs [N] 0,34 0,72 1,00 1,20 1,81 2,04
Fn [N] 1,0 2,0 2,5 3,0 4,0 5,0
μ= 0,34 0,36 0,40 0,40 0,45 0,41
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9.3. Determination of friction between plastic / felt surface pairs In order to determine the friction force and friction coefficient, Friction Plate: Plastic Friction Body: Felt-coated surface (1 N) Friction speed: Small diameter cable winder is used.
Table 6. Friction between plastic / felt surface pair(μ=Fs/Fn).
Fs [N] 0,29 0,74 0,90 1,12 1,43 1,65
Fn [N] 1,0 2,0 2,5 3,0 4,0 5,0
μ 0,29 0,37 0,36 0,37 0,36 0,33
Fig. 9. Effect graph of surface pairs on friction force
10.Results According to the graph in Figure 9, the greatest friction coefficients between the surface pairs are found in the glass and pad surface pair, and the smallest friction coefficients are found in the aluminum and brass surface pair.In the experiment, some measurement errors may occur during measurement of values. Depending on this fault, some deviations have occurred in the linear curve of the normal force-induced friction force. Experiments made with a pair of different materials showed that the glass / felt pair was the most abraded and the aluminum / brass material pair was exposed to the least friction and compressive force at the end of the period when the different materials started to act with friction and normal force at the beginning.
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REFERENCES [1]. Senai Yalcinkaya.,Marmara University, Institute of Science, "Friction and wear theories",master course notes, Istanbul Turkey, 2017. [2]. G.U.N.T., “Friction on the inclined plane1‖, Geratebeu GmbH, Hans Kempring 15-17, D-22885, Hamburg,Germany 2016. [3]. Erdem Koç,“Machine Elements”, 3rd Edition, Volume II, Nobel Publishing House, Adana, Turkey, 2009. [4] P.A.Hilton.,“Fundamentals of statues equipment for engineering education.‖ Barbette, Hamburg Germany, 2016. [5].G.U.N.T.,“Supplementary setting inclined plane and friction‖. Hamburg. Germany, 2016.
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ANALYSIS OF POINT CONTACTS USING THE COMBINED BOUSSINESQ-CERRUTI PROBLEM
Prof.dr.eng. Stefan GHIMISI, Constantin Brancusi University of Târgu Jiu, [email protected]
Abstract.For "non-conforming" contact where deformations are small enough compared to body dimensions, the theoretical elasticity will apply to the closed contact defined by the contact area.The tension can be calculated by considering each body as a solid semiinfinite, limited by a flat surface, that is to say a semisphere of elasticity. This idealization, where the bodies have the surface of the arbitrary profile and seen as a semifinished extension is almost universal for the elastic contacts.Tensions and displacements in the elastic semisphere can determine surface tractions being deduced for the first time by Boussinesq (1885) and Cerruti (1882) who have made the theory of potential, and this approach is presented by Love as well (1957)
Keywords: deformation, stress, displacements, semispaces.
1.Introduction
For "non-conforming" contact where deformations are small enough compared to body dimensions, the theoretical elasticity will apply to the closed contact defined by the contact area [1], [2]. The contact tensions is concentrated, being closed in the contact area and rapidly decreasing with the distance from the contact point. Thus, the region of practical interest is closed at the interface of the contact. By conditioning the dimensions of the body as being larger than the dimensions of the contact area, the contact contact tensions is not critically dependent on the distance of the bodies from the contact area. The tension can be calculated by considering each body as a solid semiinfinite, limited by a flat surface, that is to say a semisphere of elasticity. This idealization, where the bodies have the surface of the arbitrary profile and seen as a semifinished extension is almost universal for the elastic contacts. [3]
2. Applying the Boussinesq-Cerruti problem
In the following, pressures and deformations produced in the elastic semi-stretch limited by a plane surface, z = 0, shall be considered under the action of a tangential and normal traction applied to the area S in the vicinity of the origin. Outside of the loading axis both tensions are null. Thus the problem of elasticity is one in which the tractions are not specified everywhere on the whole surface with z = 0. In order to restrict the area where the load is applied, it will be considered the moment when all the pressure components reach zero. The loading is two-dimensional: the normal pressure p (x, y) and the tangential traction qx (x, y) and qy (x, y), generally varying in both directions x and y. The two-dimensional tension system is that all six components: x, y, z, xy, yz, zx, tensions will appear.
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A special case is when the load is asymmetric with respect to the z-axis. Considering that the polar coordinates (r,,z), the presussre p(r) and the tangential stress q (r) are independent of and q (r) if present is acting in the radial direction. The tensions components rand zdisappear and the other components are independent of Tensions and displacements in the elastic semisphere can determine surface tractions being deduced for the first time by Boussinesq (1885) [4] and Cerruti (1882) who have made the theory of potential, and this approach is presented by Love as well (1957).
The elastic semispace is shown in figure 1. If a C(, ) is denoted a point on the surface inside the loaded area S, and A (x, y, z) represents a general point inside the solid body, the distance CA will be: 1 CA x2 y2 z2 2 (1) Efforts that work on S surface will be p(, ), qx(, ) şi qy(, ). The unitary efforts satisfy the Laplace equations and we can determine the potential functions based on them.
F1 qx , dd s
G1 qy , dd (2) s
H1 p, dd s where: zln( z) (3) Result potential functions:
F1 F qx , ln( z) dd z s
G1 G qy , ln( z) dd (4) z s H H 1 p, ln( z) dd z s It can be written: F G H 1 1 1 (5) 1 z z z F G H 1 (6) z x y z Love (1957) shows that the components of the elastic displacements ux, uy, use in a point A (x, y, z) of the solid, will be given by the expressions of the terms from the above functions[5,6]. So:
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1 F H 1 ux 2 2 z (7.a) 4G z x x x
1 G H 1 u y 2 2 z (7.b) 4G z y y y 1 H uz 2 (1 2 ) z (7.c) 4G z z
Fig. 1. Elastic semispace [4]
1 These relationships decrease by for long distances to the loaded region. Thus, the elastic movements, of the closed points in the loaded region, relative to the solid points distant from the loaded region () where the elastic elastic is located rather than fixed, corresponds to a two-dimensional load. The displacements will be calculated by allowing stress determination based on Hooke's law: 2G u u u u x y z x x 2G (8.a) 1 2 x y z x 2G u u u u x y z y y 2G (8.b) 1 2 x y z y 2G u u u u x y z z z 2G (8.c) 1 2 x y z z u u x y xy G (8.d) y x
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u u y z (8.e) yz G z y
u z u x zx G (8.f) x z For a normal (pure) p(, ) pressure that exists for non-friction contacts the above equations can be written[7]:
F = F1 = G = G1 = 0 So:
H1 1 H p, ln( z) dd (9) z s H 1 1 p, dd (10) z z s
1 1 u x (1 2 ) z (11.a) 4G x x
1 1 u y (1 2 ) z (11.b) 4G y y 1 uz 2(1) z (11.c) 4G z withand 1 – Harmonic functions of x, y and z, thus satisfying the Laplace equations: 2 = 0 2 1 = 0. The value ofis given by :
u u u 1 2 2 x y z (12) x y z 2G z By replacing equations (11) and (12) in equations (8) the expression for the tensions components in a solid point is expressed. These are: 2 2 1 1 x 2 z 2 (1 2 ) 2 (13.a) 2 z x x 2 2 1 1 y 2 z 2 (1 2 ) 2 (13.b) 2 z y y 1 2 z z 2 (13.c) 2 z z
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2 2 1 1 xy (1 2 ) 2 (13.d) 2 xy xy 1 2 z (13.e) yz 2 yz 1 2 z (13.f) zx 2 xz
It can be noted that the tensions z, yz and zx depend on a single function . The tension components x şi y depend on the function 1 but their sum does not depend, therefore: 1 2 x y (1 2 ) z 2 (14) 2 z z At the solid surface the normal tension will be:
1 p(,), înside S z (15) 2 z z0 0, outside of S And the displacements will be:
1 2 1 u x (16.a) 4G x z0
1 2 1 u y (16.b) 4G y z0
1 1 1 u z ( ) z0 (16.c) 2G z z0 2G
Equations (15) and (16.c) show that normal pressure and normal displacement within the loaded area depend only on the potential function . If pressure distribution within S area is known then stresses and displacements at a point in the solid will be discovered. In practice, obtaining tension expressions at a point in the solid presents a number of difficulties. For particular conditions, the coordinates of the rectangular points in the ellipsoidal can be changed, thus solving the problems in which the contact area is limited by an ellipse (Lur'e - 1964 [135], Galin - 1953, de Pater - 1964)[8,9]. For circular contact areas, a special stress-function complex suggested by Rostovtzev (1953) (and also by Green and Zerna, 1959) can be used to detect tensions when the movements are specified within the loaded area. For axial symmetry cases, the integrals transformation method discovered by Noble and Spence (1971) (and Gladwell 1980) can be used.[10] 17 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
Another way to determine stresses and deformations at a point within the load area is to overlap the effects of a normal load and tangential force, solving the problems based on numerical analysis.
3.Conclusions
Applying the Boussinesq-Cerruti problem allows the determination of the pressures and deformations produced in the elastic semi-suspension limited by a flat surface under the action of a tangential and normal traction applied to the S. surface area Normal pressure and normal displacement within the loaded area depend only on the potential function.
4.References
[1].Archard J.F., Hirst W., The Wear of Metals Scient., Lubricat, Nov.1958,p.3-8. [2].Archard J.F.,Wear, Proc.NASA, 1967, Ed NASA, Wasinghton, 1968 p.267-333 [3].Jhonson, K.L.,Contact Mecanics,Cambridge,Cambridge University Press, 1985, 452p [4].Boussinesq, J.Aplication des potential a l'etude de l'equilibre et du mouvement des solides elastiques, Paris , Gauthier Villars, 1885,p.580 [5].GhimișiȘtefan, Fenomenul de fretting, Editura Sitech, Craiova, ISBN 973-746-422- 2, ISBN 978-973-746-422-4, 2006, pag. 331; [6].Ghimiși Ștefan,Elemente de tribologie, Editura MatrixROM, Bucureşti, 2005, ISBN 973-685-903-7, pag. 160; [7].Timoshenko, S.,Goodier, J.N.,Theory of Elasticity,New York,London et al,McGraw-Hill,1951 [8].Ghimiși Ștefan,The displacements in the fretting phenomenon,Annals of the „Constantin Brâncuși‖ University of Târgu-Jiu - Engineering Series, ISSN 1842-4856, Nr.4/2014, pag. 25-29; [9] Ghimisi, S. "An elastic-plastic adhesion model for fretting, 15th." Symposium ―DanubiaAdria‖, Bertinoro, Italia. [10] Ghimisi, Stefan. "Analysis of point contacts subjected to a tangential concentrated forces." Fiability & Durability/Fiabilitate si Durabilitate 2 (2016).
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STUDY OF A PROBLEM OF GRAPHIC ENGINEERING
Prof.PhD. Liliana LUCA, University Constantin Brancusi of Targu-Jiu, [email protected]
Abstract. The paper proposes an approximate graphical method for determining the development of the revolution surface obtained by means of the deltoid. The approximate development of the revolution surfaces are based on general methods of development, provided by Descriptive Geometry.
Keywords: development, revolution surface, deltoid.
1. Introduction
Cycloidal curves have multiple applications in technics. Their study and graphic representating a great interest to many specialists in the field of machine building, decorative art and architecture, as well as for teaching (teaching staff). Cycloidal curves are classified into 3 main categories: cycloids, epicycloids and hypocycloids. The cycloid is the curve described by a point that is on a circle that rolls without friction on a straight line. The epicycloid is the curve described by a point on a circle radius r that moves without friction outside the radius of circle R. Hypocycloid is the curve described by a point on a circle of radius r that moves without friction on the inside of a circle Of radius R. Some epicycloids and hypo-cycloids are known as having a nice shape. In this paper we start from a particular case of hypocycloid, the curve called the deltoid, a beautiful curve. This curve rotates around a vertical axis that is also the axis of symmetry of the curve and so it is obtained a revolutionary surface. For the obtained geometric surface we study the determination of the approximate deployment by the graphic method. The graphic method adopted is similar to gores method presented in [1] and [6]. Studies about the development of rotation surfaces generated by astroid, hypocycloid with 4 branches and ellipsoid, are presented in the papers [2] , [3] and [4]. In [5] is presented aesthetic forms of hypocycloids and generator mechanisms.
2. Geometrical properties of deltoid
The deltoid is a hypocycloid of three cusps. In other words, it is the roulette created by a point on the circumference of a circle as it rolls without slipping along the inside of a circle with three or one-and-a-half times its radius. It is named after the Greek letter delta which it resembles [9]. A deltoid (or tricuspoid) is the locus of a point on the circumference of a circle rolling inside another circle with a radius three times larger in magnitude. It is a hypocycloid, a curve formed by a point on the circumference of a rolling circle internally tangent to another, larger circle [10]. The deltoid was studied by Euler in 1745. This curve was first considered by Euler in connection with an optical problem. It was also investigated by Steiner in 1856 and is sometimes called Steiner curve. Thus, in geometry the deltoid is called tricuspoid or Steiner curve. 19 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
The equation of the hypocycloid: R r x R rcos a cos r (1) R r y R rsin asin r where : a - the distance of the generator point P to the center of the generator circle, φ - the angle of position of the generating point to the vector radius , R, r - the radius of the base circle and the generator circle. Depending on the value of parameter a, the hypocycloid may be normal, elongated or shortened. The graphical construction of the normal hypocycloid cell is given in figure 1.
Fig.1. The hypocycloid, [7]
The equation of the deltoid is obtained by setting R/r=3 in the equation of the hypocycloid, where R is the radius of the large fixed circle and r is the radius of the small rolling circle. A normal deltoid can be represented by the following parametric equations: 2R R x cos cos 2 3 3 (2) 2R R y sin sin 2 3 3 Or, x 2r cos r cos 2 (3) y 2r sin r sin 2
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The total arc length, from deltoid is : S3=16R/3.
2 The area from deltoid is: A3=2π R /9.
The deltoid is presented in figure 2.
Fig. 2. The deltoid, [8]
3. Approximate development of the revolution surface obtained by rotation of the deltoid
Figure 3 shows the revolutionary surface obtained by rotating the deltoid around the vertical axis zz ', the axis coinciding with the deltoid symmetry axis. The deltoid is defined by the fixed circle (the director circle) - Cf and the generator circle-Cg. The resulting surface consists of two parts: a surface having the V1 peak and the CD diameter circle, and the second surface having a pole in V2 and as a basis the circle of CD diameter.
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Fig. 3. Surface generated by rotation of the deltoid.
Figure 4 shows the projections of the surface in the orthogonal projection system, on the vertical projection plan and on the horizontal projection plan. The graphical construction of a spindle is also presented. In order to find out, the surface with auxiliary plans is divided into two categories: horizontal plans and vertical plans. The vertical plans drawn equidistantly divide the surface into several equal parts called gores. It is proposed the cutting of this surface with a number of 5 equidistant vertical plans (P1, P2, P3, P4, P5) and six level plans (N1, N2, N3, N4, N5, N6). Thus, the graphically drawn is made up of 10 gores and the drawing obtained for a gore has an acceptable clarity. The sectioning level surface plans [N1], [N2], [N3], [N4], [N5], [N6], determine circles ‗ ‗ ‗ ‗ that are represented in a [H] project plan. Vertical traces of planes are noted: n1 , n2 , n3 , n4 , ‗ ‗ n5 , n6 . The vertical section plans [P1], [P2], [P3], [P4] and [P5] is represented in the [H] project plan, through the horizontal tracks: p1, p2, p3, p4, p5. The intersections of two consecutive vertical planes with the 6 planar planes and the revolutionary surface give the points describing a gore. These points are denoted in horizontal projection [H]: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 si 14.
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Fig. 4. Projections of the revolution surface and drawing for a gore.
For tracing the evolute of a gore (picture 4), it is drawn a straight line segment V10 V20. The segment has a length equal to L1 + L2. The length L1 is the length of the arc v1 'b' and is L1 = 16R / 9. The length L2 is the length of the arc v2 'b' and is L2 = L1 / 2 = 16R / 18. Then the two lengths L1 and L2 are divided into four equal parts. There are drawn in the dividing points perpendicular segments, symmetrically arranged lengths equal to the strings underlined by the circular arcs that are defined by the level planes are plotted at the points of division. In the run of the gore the chords are noted: 1020, 3040, 5060, 7080, 90100, 110120, 130140. The points thus obtained are joined together and the profile of a gore is obtained.
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In figure 5 it is given the development of a revolution surface , consisting of 10 identical gores. The gores are drawn adjacent to a straight segment 1010, having the length L. The length L is calculated with the relation: L = 2π ρ, where ρ is the radius of the base of the ‘ ‘ revolution surface (ρ= O3 b ).
Fig. 5. Approximate development of the revolution surface
This evolute has errors due to the approximation of the circular arcs with underlined strings plus the errors specific to a graphical construct with geometry tools. Errors can be reduced if one runs with as many gores as possible, but in these cases the drawings are less clear.
4. Conclusions
Cyclic curves or cycloids are a category of curves of particular importance in mathematics, descriptive geometry, but especially in technique, being applied to many mechanisms. Cyclical curves have many applications in construction, architecture, ambient design, especially aesthetically pleasing cycloid variants. The revolutionary surface obtained with deltoid is also a beautiful surface, with special aesthetics, which can find multiple uses. In some applications, it may be necessary to determine the surface to be developed. The paper proposes an approximate graphical method for determining the development of the rotational surface obtained by means of the deltoid. The approximate development of the revolution surfaces are based on general methods of development, provided by Descriptive Geometry.
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The proposed method is approximate, it has errors generated by the approximation of circular arcs with underlined strings as well as inherent errors of graphical methods. Errors can be reduced by using as many as possible auxiliary plans (horizontal and vertical plans), but here are limitations imposed by the clarity of the construction. A more accurate deployment, with much smaller errors, can be achieved with computer-assisted methods, using appropriate programs. It can be made a program for determining the errors.
References 1.Moncea, J. – Geometrie descriptivă şi desen tehnic. Partea I. Geometrie descriptiva. E.D.P. Bucureşti 1982. 2. Luca L., Buneci M., Stancioiu Alin, Radulescu C., Study on a method for determining as accurately as possible the development of an ellipsoid. Annals Constantin Brancusi University of Targu Jiu, Engineering Series, no. 1/2015, ISSN 1842-4856, Academica Brancusi Publishing House. 3. Luca L., The development of a rotation surface generated by astroid. Annals Constantin Brancusi University of Targu Jiu, Engineering Series, no. 4/2016. ISSN 1842-4856. Academica Brancusi Publishing House. 4.Luca L., The development of a rotation surface generated by hypocycloid with 4 branches. Journal Fiability and Durability, no.2/2016. ISSN 1844-640X, Academica Brancusi Publishing House. 5. Popescu I. , Luca L., Aesthetic effects of hypocycloids generator mechanisms. Annals Constantin Brancusi University of Targu Jiu, Engineering Series, no. 4/2014. ISSN 1842- 4856. Academica Brancusi Publishing House. 6. Simion, I., Geometrie descriptiva. Editura Bren, 2002. 7.http://www.lanubeartistica.es/Dibujo_Tecnico_Segundo/Unidad1/DT2_U1_T4_contenidos_ v01/32_hipocicloide.html
8.https://www.google.ro/search?q=hipocicloide&newwindow=1&tbm=isch&tbo=u&source =univ&sa=X&ved=0ahUKEwj1t7T3w8_TAhVE3CwKHSh9Aq8QsAQIOQ&biw=1034&bih= 871#imgrc=EeTk5So0SguUPM:
9. https://en.wikipedia.org/wiki/Deltoid_curve
10. https://geometryatlas.com/entries/238
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THE INFLUENCE OF THE CONSTRUCTIVE PARAMETERS ON THE VIBRATION INHERENT FREQUENCIES AT BENDING FROM TWO- SHAFTS TRANSMISSION
Ion BULAC Doctor, University of Pitești, email: [email protected]
Abstract- The shafts transmissions that can be treated as the elastic linkage systems of various sections, length and specific weights, suspended on elastic supports. The average fiber elastic deforms under the action of own weight static, generating a mass eccentric to the axis of rotation of its own.The eccentric mass during the even rotation produces a centrifugal force, which increases the elastic deformation leading to the occurrence of bending vibration. The own pulses of this vibrations depend on the mechanic and constructiv caracteristic of the cardan transmissions. This paper presents the influence these characteristic over the frequencies and vibration modes inherent at bending and based on numerical simulations will draw conclusions
1. INTRODUCTION The operation of the speed shaft transmissions at or near the natural frequency of the pulses at the resonance phenomenon leads to bending, when the amplitude of the oscillations increases sharply, causing deterioration or complete destruction thereof. The avoiding overlapping frequencies over the intersections of the disturbing harmonics n, 2n, 3n, (n being the transmission speed), [1], [2] can also be done by adopting appropriate constructive measures.
2. THE CONSTRUCTIV MODEL AND THE EQUIVALENT MECHANICAL MODEL OF THE MOBILE TWO-SHAFTS TRANSMISSION Model constructive of the mobile two-shafts transmission (see Fig. 1.a.) is attached to the equivalent dynamic model, [3], [4] (see Fig. 1.b.) consists of three sections influences the shape of the shaft fork (l1), pipe drive shaft (l2) of the grooved portion of the drive shaft and a fork head connecting with the cross shaft of B (l3). In sections A and D are located about the chassis elastic supports having elastic constants kA ;kD In the paper, [5] is presented the mathematical model and algorithm for calculating the pulsations of vibration at bending of the two-shafts transmission without technological deviations.The connection between the pulsations and the mechanical and constructive characteristics is given through the parameters i ;zi defined by relations [3] -[5]:
2 i Ai i 4 p ;zi i li (1) Ei Iyi where p,li ,i ,Ai ,Ei ,I yi - is respectively, the vibration inherent pulse the length, density, area, transverse modulus of elasticity and geometrical moment of inertia mainly for the section corresponding to the index i 1,2,3 (in our case the cardan was divided into three sections).
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Fig. 1. Constructive model and equivalent mechanical model These parameters intervene in the characteristic equation ( p ) 0 (2) by the solving are deducted the own pulses p1 , p2 ,…,.
3. RESEARCH AND RESULTS Based on the mathematical model and the algorithm presented, in the paper, [5] and a computer program developed in Excel, numerical simulations, [6] were made on three mobile two-shafts transmissions of different lengths (see Fig. 1.). The coupling elements of the mobile two-shafts transmission with the back axle and gearbox of the car have the same dimensions. For these cardan transmissions are known the following construction and mechanical caracteristic 6 4 2 3 kA kD 8510 ( N / m);A1 A2 A3 19,6 10 ( m );1 2 3 7800( kg / m ) for cardan transmission with drive shaft from constant section bar 6 4 2 4 2 3 kA kD 8510 ( N / m);A 1 A3 19,6 10 ( m );A2 3,6 10 ( m );1 2 3 7800( kg / m ) for cardan transmission with drive shaft from the pipe. The component tronsons considered of the cardan transmissions are divide in the equal sections by 0,06m, according to the TABLE 1.
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TABLE 1. Cardan AB BC CD length l1 Number of l2 Number of l3 Number of [m] [m] sections [m] sections [m] sections 0,9 0,06 1 0,60 10 0,24 4 1,5 0,06 1 1,20 20 0,24 4 2,1 0,06 1 1,80 30 0,24 4
For the first approximation the double drive shaft transmission is replaced with a constant section bar, yielding seats at both ends. For the cardan transmission with the length -1 L1=0,9(m), the following values for the characteristic pulses were obtained p1=774,3791(s ) respectively p2=2907,5665(s-1). Corresponding to this pulse graphs were drawn at the bending vibration inherent modes shown in Fig. 2.
Fig. 2. The vibration mode corresponding to the first two inherent pulses for the two-shafts transmission asimilated with a constant section bar. In the real case of the two shafts transmission, where the drive shaft is from the pipe, having at both ends the cupling forks,the values are obtained for first and second pulsatio n own p1=896,0115 (s-1), p2=3262,2419(s-1) and the bending vibration inherent modes shown in Fig. 3.
Fig.3. The vibration mode corresponding to the first two inherent pulses for the real two-shafts transmission
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For the other transmission with the lengths L2=1,5(m) and L3=1,8(m) values of the own pulsations result from the numerical simulations in the two cases considered, are presented in TABLE 2.The shape of their own vibration modes differs by the coordinates of the points where the maximum vibration amplitudes occur. TABLE 2 Drive shaft from Drive shaft from the Cardan constant section bar pipe length p1 p2 p1 p2 (m) -1 (s ) (s-1) (s-1) (s-1) 0,9 774,3791 2907,5665 896,0115 3262,2419 1,5 283,2368 117,1629 325,2445 1228,6995 2,1 144,9149 576,4699 166,1817 631,6675
Corresponding to the values in the TABLE 2, the graphs of variation were drawn of the first own pulse according to the length of the cardan, in the two cases considered, as shown in Fig. 4.
Fig.4. The variation of the first own pulse From the results of the numerical simulations and the variation diagrams presented, it can be seen that the values of the pulsations of the vibration at bending decrease as the length of the cardan transmission increases and increases as its rigidity increases.
6. CONCLUSIONS Numerical simulations provide important information on the behavior of the transmission to different operating modes. The size of the pulses and their occurrence of the maximum amplitude (the stronger the applied) can be controlled in a certain range of values by the structural measures taken in components of the transmission and the way of connection of the assembly support or abutment elements.
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REFERENCES [1] Dudiţă, Fl., Cardan shafting, Technical Publishing House, Bucharest, 1966. [2] Dudiţă, Fl., Diaconescu, D., Bohn, Cr., Neagoe, M., Săulescu, R., Cardan shafting, Transilvania Expres Publishing House, Brașov, 2003 . [3] Voinea, R., Voiculescu, D., Simion, Fl., Introduction in the solid mechanics with applications in engineering, R.S.R. Academy, 1989. [4] Ripianu, A., Craciun, I., Axles, righteous shafts and crankshafts, Technical Publishing House, Bucharest, 1977. [5] Bulac, I,. Vibrations of the bicardanic transmissions with elastic supports, 5th Symposium „Durability and Reliability of Mechanical Systems‖, SYMECH 2012, Târgu-Jiu, Romania, 18-19May, 2012. [6] Stanescu, S., Numerical methods, Didactic and Pedagogical Publishing House, Bucharest, 2007.
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PRACTICAL METHOD FOR DETERMINING THE DYNAMIC COEFFICIENT
Assoc. Prof. Minodora PASĂRE Constantin Brancusi University of Tg-Jiu, Romania [email protected],
Abstract: In practice collision is between two bodies, one which is carried kicking and moving, and another is hit and is at rest. There were obtained by shock request. The number of times the dynamic coefficient are greater effects (stress and strain) caused by dynamic loading, as compared with the same load applied to the shock and called static load with the dynamic load equivalent studied. Dynamic coefficient is determined basically by measuring static and dynamic arrows that appear at a requested beam weighing suddenly falls from a height known. Sizes arrows static and dynamic compared to what theoretically obtained by calculations.
Key words: stress, energy, shock
1.Introduction Dynamic stress due to application tasks that have a certain speed or to be applied sharply (shock). Applying sudden dynamic load causes an elastic body has two distinct states, a state shock effect resulting from spreading throughout the body mass and a local state around the site of impact. In practice collision is between two bodies, one which is carried kicking and moving, and another is hit and is at rest. Thereby obtaining a request by shock. If the body is at rest stops him whoever is in motion, the shock that occurs can be determined based on the law of conservation of energy [1]. The kinetic energy of a moving body is: 1 E v2dm (1) c m 2 v is the velocity of a component of mass dm. For the translational movement bodies, the kinetic energy is: 1 E mv2 (2) c 2 and for bodies which have a rotational movement about an axis fixed kinetic energy is: 1 E I2 (3) c 2 Where ω is the angular velocity and the moment of inertia I of the solid to the axis of rotation. Body weight G, which falls from height h, has a kinetic energy that is equal to mechanical work (outside) made will be E L Gh (4) c e Based on the energy conservation law can admit that the kinetic energy of the body turns off potential energy of deformation of two bodies:
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E W sau L W (5) c e Following the collision the two bodies suffer deformations and store both energy and total energy is: E W W (6) c 1 2
Where W1 and W2 are the deformation energy of the two bodies.
2. Determination of dynamic coefficient practice The number of times the dynamic coefficient are greater effects (stress and strain) caused by dynamic loading, as compared with the same load applied to the shock and called static load with the dynamic load equivalent studied. If claiming bending G weight falls on a bar (Figure 1) at the height h. The bar is resting easy and has a modulus of rigidity EI and length l. The kinetic energy of the weight hits the bar is at the time of shock [2]:
E L Gh (7) c e
By hitting the weight exerted on the bar a dynamic force Fd> G that bend bar. The two portions of the beam bending moment will be [2]:
x x M 1 M ; M 1 M (8) 1 a max 2 b max
Fig. 1 Displacement given by shock
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The potential energy of deformation of the beam will be:
2 1 a 2 b 2 M l W M dx M dx max (9) i 2 2EI 0 0 2EI
From equal Ec = W is obtained Mmax, 6EIGh M (10) max l
It is noted that the maximum bending moment does not depend on the site of the shock; the hail is longer shock is much weaker. The maximum voltage will be: M 6EIGh y 6EGh max max (11) max 2 i W lW z v
It follows that the stress is even lower as the beam volume is higher. Dynamic force that produces σ max stress can be calculated:
M l 1 F max 6EIGhl (12) d ab ab
These sizes can be used to determine coefficient practical impact (dynamic factor). It is thought the scheme in Figure 2, where a beam is subjected to bending due to the fall of weights [3]:
Fig. 2: Beam requested to bending by shock
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If claiming bending caused by dropping a weight on a beam (Figure 2) can write relations:
fd fst d st (13) Where dynamic coefficient (impact) and has the expression:
2h 1 1 (14) f st The dynamic factor expression (8) h is the height of fall of the load that causes shock and static displacement fst is having expression for simple beam resting at the ends: Pa 2b2 f st (15) 3EI zl
BH 3 where: I ; E 2,1105 N / mm2 z 12 Basically, dynamic factor determining the impact is utlizând a bar resting on two supports that can move along a guide during the experiment, with the possibility to perform various openings beam. Shock request is made using a weight with the known mass, which can slide on a support. Falling height h can be changed. Following the sudden drop in weight, deformed bar, appearing as an arrow, which can be measured with a registrar compound a scoring device fixed on the beam and a drum rotated by an electric motor. Knowing the support spacing and position of the request, the weight is fixed at a certain height h. In this case, the device will trace the line of the request. Triggering weight located at height h, and the recording dynamic arrow is determined by measuring the maximum amplitude of oscillations and static arrow. Device application moves to another position and repeat measurements. The deflection of static and dynamic measurements obtained are compared with those calculated by the formulas set forth above.
3. Conclusions The number of times the dynamic coefficient are greater effects (stress and strain) caused by dynamic loading, as compared with the same load applied to the shock and called static load with the dynamic load equivalent studied. Collision of moving parts to another, at rest, in motion kinetic energy of the piece turns into potential energy of deformation of the workpiece hit. Dynamic coefficient is determined basically by measuring static and dynamic arrows that appear at a requested beam weighing suddenly falls from a height known. The sizes of static and dynamic displacement are compared to what obtained by theoretical calculations. 34 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
References [1]P.Tripa,Strength of Materials, Publishing House Mirton, Timisoara, 2001 [2]MihăiţăGh., M. M. Pasăre, G. Chirculescu,Strength of Materials, vol. I+II, Publishing House Sitech, Craiova, 2002. [3] Pasăre M.,Ianasi C., Aspects regarding the determination of dynamic coefficient,FiabilitatesiDurabilitate - Fiability& Durability No 2/2016 Editura ―AcademicaBrâncuşi‖ , Târgu Jiu, ISSN 1844 – 640X, pg.118-121, 2016 [4] BuzduganGh., Strength of Materials, Publishing House Technique 1975 [5]M. Rades, Strength of Materials, Printech Press Publishing House, Bucharest, 2010 [6] Ianăşi C. Research on reducing the risk of damage for the resistance elements of wooden building,2nd WSEAS International Conference on RISK MANA GEMENT, ASSESS MENT and MITIGATION (RIMA '13) Brasov, Romania, 2013, pp. 161-164, ISSN 2227-460X
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CONTRIBUTIONS TO THE DYNAMIC ANALYSIS OF THE TORQUE TORSION TORQUE OF MECHANICAL TRANSMISSIONS WITH WHEEL WRENCHES
Gheorghe DRĂGUŢ, „Constantin Brancusi‖ University of TarguJiu, ROMANIA
Abstract:The study of mechanical transmission parameters is one of the most important problems both for couplings and for shafts and types of gears. In order to determine the deformation, the torque and implicitly the transmission errors of the rotation motion for a mechanical transmission with straight toothed cylindrical gears, this paper presents a solution for analyzing the transmitted moments of dynamically driven shafts. This solution started from the existence of two diamond halves located diametrically opposed on each of the two experimental stand shafts.
Key words: Experimental stand, torsion torque, longitudinal grooves, phasing.
1. INTRODUCTION
An experimental stand designed for this purpose and experimental determination of cylindrical gears were used to perform the measurements. In accordance with [1] and the data of FIG. 1 the main components of the stand are: pos.1. Electric motor; Position 2, coupling between the electric motor and the main shaft, pos. 3 the motor shaft, which conveys the rotational movement of the toothed wheel 5 engaging the toothed wheel 6 mounted on the shaft in pos. The couplings 7, 11, 15 connect the shafts 9, 13, 17 and impart the rotational movement through the gears 19 and 20 to the driven shaft 18. The coupling 11 is composed of two half-couplings with side coupling teeth in order to be able Disassembling them with one or more teeth to load the system. On shafts 17 and 18 are mounted the semipunks needed to measure torsional moments. Couplings 8, 12 and 14 complete with the shafts 10 and 14 the kinematic chain of the system. To ensure proper assembly with the semicuplanets for all the shafts, longitudinal grooves were machined. Very important for determining the torque values on the shafts without loss of coupling is their special construction, positions 8, 12 and 15.
Fig. 1. The kinematics of the experimental stand
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2. CAPTLE SETTING FOR MEASURING THE TORQUE TIME
The cylindrical gearing bench is equipped with tensometric transducers for measuring torque. HBM type XY2x type strainers are used, connected to Wheastone bridge. [http://www.hbm.com/en/3444/xy2-xy4-torsion-shear-strain-gauges-with-2-measuring-grids/] The transmission of the measurement signal from the shaft to the fixed part is made by brush- type systems, such as HBM-SK-6, fig. 2. To load the shaft with different torques, we used a lever mounted on the flanges mounted on the shafts at the end of which we suspended 4.8 kg. The lever arm, shown in fig. 3, is 1 m. Charging was done progressively, starting with the first weight, then we added extra weight, obtaining a progressive loading in steps. For each load stage we read, with the help of the HBM measuring system, MGC Plus, the deformations produced by the torque, fig. 3 and 4. The calibration graph of the shaft I is shown in fig. 2.
Fig.2. Moment of torsion - deformation, for shaft I
The graph in fig. 2, was plotted in Excel on the basis of the experimental results presented in Table 1. The torque was determined taking into account the lever arm at the end of which weights were mounted, 1 meter.
Table 1. Calibration of the torque transducer mounted on shaft I Parameter Weight Torque Specific [kg] moment[Nm] deformations [µm/m] 0 0 0 4,8 47,088 23,34 9,6 94,176 47,93 14,4 141,264 71,74 19,2 188,352 95,72 24 235,44 121,3 28,8 282,528 145,34
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In the same way, I proceeded to the tree II of fig. 1. We represented the characteristic moment of torsion-deformation, for the transducer mounted on the shaft II, in fig. 3.
Fig. 3. Torque moment - deformation characteristic, for shaft II
The calibration feature of the transducer mounted on the shaft II was based on the experimental data presented in Table 2.
Tab. 2. Calibration of the torque transducer mounted on the shaft II
Parameter Greutate Torque Specific [kg] moment[Nm] deformations [µm/m] 0 0 0 4,8 47,088 25,42 9,6 94,176 51,58 14,4 141,264 77,71 19,2 188,352 103,56 24 235,44 129,93 28,8 282,528 155,48
3. EXPERIMENTAL RECORDS
Experimental records were performed in two situations: for the no load system as well as on the internal loading system, performed by torsion of the I. line. For recording the experimental data, the MGCPlus measuring system, produced by HBM, is connected using the USB interface to a Notebook computer equipped with the Catman Easy software. 38 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
In the first phase tests were performed to record torque moments for the unladen system, ie for idling. The booth was started and deformations were recorded, as shown in fig. 4, where we presented an aspect of the CatmanEasy recording software.
Fig. 4. Appearance of the CatmanEasy recording software window
The recorded deformations were saved in the form of an ASCII file, these data were imported into Microsoft Excel where they were multiplied by the calibration coefficient of the drifting caps to obtain torque variation. For the idling, four attempts were made. In fig. 5 and 6 show the results obtained in Excel for the first and second attempts.
Fig. 5. Torque-zero torque records 1.
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Fig. 6. Load-torque torque records 2.
The engine idling speed was about 1430 rpm. Since there are two pairs of gears, the yield value is calculated by: TT 2 22 (1) TT11 Where: is the yield of a cylindrical gear;
T2 - The mean torque moment on shaft II;
T1 - The mean torque moment on shaft I. Taking into account the four experimental determinations carried out for idling, we determined the mean torque moments on trees, and we calculated the yield values for each determination, as shown in Table 3.
Table 3. Determination of empty run efficiency
Determination T2 T1 [Nm] [Nm] 1 4,111 5,532 0,862 2 4,240 5,841 0,851 3 2,915 4,815 0,778 4 3,483 6,662 0,723 4 0,803 i Media: i1 4
The loading of the system was achieved by rotating the shaft line half-shafts I and the teeth coupling of the teeth coupling. This coupling was mounted precisely to achieve system load. As compared to the initial positioning of the coupling teeth corresponding to the unladen system, the positioning was dispensed with a tooth of the coupling flanges. In this way an internal torque moment is made in the circuit of the two gears. The internal torque 40 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
generated by rotation of the shaft half-shafts I equates the transmission shafts equally. The original recording of the deformations resulting from the torsion of the semi-shafts is shown in fig. 7.
Fig. 7. Deformations recorded on the transmission shafts by torsion.
By torsioning the shafts, due to the different stiffnesses of the sections on which the tensometric stamps are attached, different deformations occur: 287.72 μm / m on the tree I and 302.97 μm / m on the tree II. These deformations correspond to torques of 557,889 Nm and 548,981 Nm for the shaft II. With the system loaded by the torsion of the tree line I, we performed a number of 4 tests, determining the variation of the torque moments present on the shafts. The results obtained are shown in fig. 8-9.
Fig.8. Variation of Torque Moments - Test 1
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Fig.9.Variation of Torque Moments - Test 2
Fig. 10. Record static system load with one tooth
4. CONCLUSIONS From the analysis of the results obtained for the idling torques shown in Fig. 5-6, the following conclusions can be drawn: - the torque recorded on the shaft I has a wider variation than that measured on the shaft II, this is explicable because the shaft I is integral with the electric drive motor. Instead, on the shaft II the torque is characterized by a pulsating variation because it is transmitted through the gearing of the wheel teeth. - in absolute value, the moment of torsion on the shaft II is less than the moment of torsion on the shaft I; - In the start-up phase of the electric motor, there is a sudden variation in torque, the variation of the torque moments stabilizes in the stable operation phase of the electric motor; From the analysis of the results obtained for tests on the loaded system, the following conclusions can be drawn: - the variation of the torque moment on the shaft I, the driving shaft, keeps its character smooth; - instead, the torque variation on shaft II increases its pulsating character due to the torsional vibrations that have occurred; 42 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
- in this case, [3] shows the effect of the gear housing on the noise generation caused by the impacts of the torsional transmission devices. - it is observed that starting and stopping of the electric drive motor there are variations of the torsion moments given by the torsional vibrations, fig. 8.
5. REFERENCES: [1] Drăguț G, - Considerations on a testing stand for mechanical transmision study, Annals of the Constantin Brâncuși Universiy of Târgu Jiu, Engeneering series, ISSUE 4/2014, pp. 65- 68; [2]Grofu F, Cercel C, Drăguţ G, - Wireless application for mechanical transmission study, Annals of the Constantin Brâncuși Universiy of Târgu Jiu, Engeneering series, ISSUE 2/2015, pp. 76-81; [3] Ogjanovic M, Ciric Kostic S, - Gear unit housing effect on the noise generation caused by gear teeth impacts, Journal of Mechanical Engineering 58(2012)5, pp. 327-337.
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ANALYSIS OF COMPENSATING CABLE CONNECTING DEVICES FOR WINDING INSTALLATION VESSELS
PhD, Eng., Assoc. Lecturer, Răzvan Bogdan ITU, Department of Industrial Mechanical Engineering and Transport, University of Petroșani, [email protected] PhD, Eng, Lecturer, Vilhelm ITU, Department of Industrial Mechanical Engineering and Transport, University of Petroşani, [email protected]
Abstract: Winding installations have the role of transporting, between underground and surface, useful minerals, materials, equipment, and people, with extraction vessels. Cable connecting devices connect winding installation cables to extraction vessels. Depending on their design, connecting cables can be: with loop and core, self-tightening with wedged core on one or both sides; with hinged jaw; with cone-shaped friction wedges; with wedges and bridles. The paper presents an analysis of flat metal cable connecting devices.
Keywords: compensating cable connecting device;
Introduction Fixing cables to extraction vessels is done by means of connecting devices and harnesses. Both connecting devices and harnesses should be safe in use and resistant to fatigue, lightweight and small, they should protect cables and should be easy to maintain. Cable connecting devices are subject to significant static and dynamic load. Besides, additional strain might occur in the form of transversal, longitudinal or torsion oscillations, due to defective mounting. Connecting devices are classified according to design and depending on the cable used. Thus, for compensating cable connecting devices one can find flat compensating connecting cables (Fig. 1), round compensating connecting cables (Fig. 2), round, vortex type compensating cable connecting devices (Fig. 3).
Fig. 1. Flat compensating Fig. 2. Round compensating Fig. 3. Round, vortex cable connecting devices cable connecting devices type cable connecting devices
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Table 1. The constructive-functional characteristics of flat cable devices for equilibrium.
Value of characteristic No Characteristic UM DLCLE- DLCLE- DLCLE- 118 129 135 1 Maximum static load tone/k N 2/20 3,5/35 5,5/55 106×15,5 124×18 2 Flat cable section mm 135×20 118×17 129×19 3 Specific cable mass kg/m 5,447/6,726 7,558/8,128 8,865 With loop and 4 Cable fixing - eccentric core 5 Bolt diameter mm 60 70 70 Cover plate width for 6 mm 40 48 40 attaching to the skip Number of fixing clamps 7 pc 6 6 6 of flat cable 8 Space btw. clamps mm 120 120 120 Length mm 1327 1577 1706 (height) 9 Size Width mm 380 460 500 Thickness mm 238 250 258 10 Weight kg 190 248 290
Device construction and functioning Main constructional-functional parts of flat cable connection The main constructive-functional parts of flat cable connecting devices for equilibrium DLCLE-118, DLCLE-129 and DLCLE-135 are shown in Fig. 4 and 5. The three typo-dimensions of flat cable connecting devices have the same constructive shape, the difference lying in the dimensions of the component elements, which are subject to different trials depending on the characteristics of the compensation cable. According to Fig. 1, such a device is made up of a series of elements of resistance making the connection between the bottom of the extraction vessel and the eccentric core, its functional width being determined by the width of the flat cable and a series of clamps for fixing the end of the cable wound around the core. The whole of the device is fixed to the extraction vessel by means of cover plate 1, which is a structure of resistance made up of four steel plates riveted between them and processed by cutting to nominal size. The connection to the eccentric core 6 is done by means of a fork 3 and two cover plates 4, made up od two steel plated riveted between them, and the connection between the three elements being made by bolts 2 and 5, made of allied steel and thermally treated. 45 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
Fig. 4. Flat cable connecting device Fig. 5.Flat cable connecting DLCLE 118, 129, 135 device for equilibrium DLCLE 118
The eccentric core is a welded metal structure, Fig. 6, with a central plate giving the shape and position of the two sleeves, and the winding plate and the exterior plates make up the canal around which the end of the flat cable is wound for compensation. The core, besides the bolt 5 sleeve also has a hole used to support the device in view of mounting the cable. The label 7 is fixed tot the core, to identify the device and the two flanges 8, having the role of fixing the flat cable to the canal of the metal core.
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Fig. 6. Eccentric core Fig. 7. Cover plate for attaching the skip
The loose end of the cable is passed along 1500 mm over the cable entering the core, the two branches being seized in six double clamps 9, each having four tightening screws 10, with nuts and counter-nuts. From the mathematical cable equilibrium and metal core model shown in Fig. 8, and from the nonslip condition of cable end blocked between clamps and cable, the clamps tightening force is N1.
Fig. 8. Flat compensating cable tightening clamp
The material of the important parts, the plates of the cover plate seizing the extraction vessel, all the connection bolts, the connection fork, the plates of the intermediary cover plate, the lower and the upper plate of the eccentric core respectively, should be monitored for defects, non-destructively, before the material flow, and should meet the prescriptions specified in the technical documentation. In the execution of the skip that seizes the cover plate, Fig. 7, of the intermediary cover plate and the lower and upper plates of the eccentric core, the following conditions should be met: - heat straightening of the sheets of which the before mentioned subassemblies are made, is not allowed; - the piece will be cut out from the sheet along the outline by chipping or thermal 47 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
cutting, in which case a processing addition of minimum 10 mm is left, which will be removed by chipping; - the piece will be cut out so that the direction of lamination of the sheet would coincide with the strain direction of the piece, along it. In the execution of the subassemblies made up of plates, the exterior and interior plates are gripped in a package and the boring for riveting is done, after which they are riveted together, and the other boring operations will be done. After assembling the plate packages by riveting, the end of the rivet is processed, so that the outside of the of the plate surface would not be extended in the exterior In order to execute the connecting bolts and forks, the forging of the material is not allowed, only its mechanical processing. Before its installation at the place of use, all the component pieces of the device are verified. The component elements showing defects or damages, which might adversely influence the functioning of the device will not be allowed. The extraction vessel to which the equilibrium device is attached is found on pegs of a safety bridge. At the upper part, the device is mounted by means of bolts to the extraction vessel, and at the lower part the flat cable is mounted by winding around the eccentric core and fixing by clamps. The daily verification of the devices is done by careful visual examination and tapping, watching whether the component parts show fissures or deformations.
Size verification of devices. Starting from the mathematical equilibrium model of the cable and metal core, shown in Fig. 9, and the non-slip condition of the end of the cable blocked between clamps and cable, the relations of determination of clamps tightening force is given below:
G e N1 - ,N (1) 1 1 e where: G is the maximum weight of the equilibrium cable, G = 20000 N; μ – friction coefficient between the cable and the metal core, μ = 0,1; θ – winding angle of the cable on the metal core, θ = 220º; μ1 – friction coefficient between cables, μ1=0,1. For a dynamic coefficient of the winding installation of 1,6 ... 2 and a safety coefficient higher than 10, a number of twenty one M20 screw result executed in OLC 35q, with a flow limit of 370 MPa. Due to the use of clamps with four tightening screws, six clamps for safe fixing of the end of the cable are required. The cover plates and fork have been tried for tear and shear in the bolt area and for contact pressure between their boring surfaces and bolts.
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Fig. 9. Mathematical model Fig. 10. Numerical analysis of fixing forces of cable with finite elements of device DLCLE 118
Bolts have been tried for strains at bending and shear, for a safety coefficient higher than 10, the use of one 42MoCr11, 31MoCr11, 31MnCrSi11 or 25MnCrSi11.alloyed steels of improvement resulting. Fig.10 shows the numerical analysis with finite elements of the device DLCLE 118, in Fig. 10,a showing the way of loading, fixing with of the boring of the bolt of attachment to the skip, and application to the surface of the metal heart of a force equal to the maximum weight of the cable, 20000 N. Fig. 10,b shows that the maximum strain of the bolts occurs in the area of separation between the cover plate an the sleeve of the metal heart due to the shear strain, this is highlighted by the detail A and B, where tensions equivalent to 69,306 MPa and 79.468 MPa come up, confirming the necessity of using alloyed steels of improvement.
Conclusions In drawing up the documentation of execution for connecting devices of flat cables for equilibrium in contract No. 193/ASL/2006, concluded with CNH Petrosani, the following technical economic aspects had been in view: - simplification of constructive solutions from technological point of view (eccentric core and clamps in welded construction compared to their cast construction);
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- equalization, as far as possible, of constructive solutions for flat cable connecting device, which equips multi-cable winding installations in the Jiu Valley. This was particularly difficult, since it was necessary to maintain the inter changeability with the present constructions; - use of constructive solutions that had been verified in practice for similar devices; - maintaining the present safety coefficient , and in some cases, its increase; - decrease of costs by reducing manoeuvre.
References
[1] Dumitrescu I., Cozma B., Urdea Gh. B., Study of Coal Transportation Flow from the face to the Ground in Lonea Mine, 15 th GeoConference on Science and Technologies in Geology, Exploration and Mining SGEM 2015, Conference Proceedings, vol. III, pp. 603 – 610, ISBN 978-619-7105-09-4, ISSN 1314-2704. [2] Dumitrescu I., Cozma B., The constructive analysis of the borer heads for the rotative boring, Proceedings of the 13th International Conference, Modern Tehnologies, Quality and Innovation, ModTech 2009, Iaşi, 21-23 mai 2009, pag. 243-247, ISSN 2066-3919. [3] * * * ―Execuţia desenelor pentru piesele de schimb vase de extracţie (DLC, tije, arcuri, DEC şi DLCLE)”. Contract nr. 193/ASL, 18.12.2006, C.N.H. Petroşani.
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DIAGNOSIS OF THE WINDING MACHINE IN THE OLD SHAFT WITH SKIP IN LONEA MINING PLANT
PhD, Eng., Assoc. Lecturer, Răzvan Bogdan ITU, Department of Industrial Mechanical Engineering and Transport, University of Petroșani, [email protected] PhD, Eng, Lecturer, Vilhelm ITU, Department of Industrial Mechanical Engineering and Transport, University of Petroşani, [email protected]
Abstract: To study the operation of the winding machine in the Old Shaft with Skip in Lonea Mining Plant, the dynamic analysis of the driving wheel (Koepe wheel) was performed, by resistive electric tensometry methods, acceleration measurements, and vibromechanical analysis on the bearings of Koepe driving wheels, on functioning cycles and vibromechanical analysis of the reduction gear. The paper presents aspects regarding vibromechanical measurements and resistive electric tensometry methods in the winding machine..
Keywords: compensating cable connecting device;
Introduction Underground extraction of coal and rock in Lonea Mining Plant is done by the winding installation of the Old Shaft with Skip made up of the winding machine in the tower as well, provided with two skips, 8 ton each. Any malfunction in the functioning of the winding machine with the Old Shaft with Skip, can lead to important losses in production, and to endangering the safety of the seam and of the workers. Along the years, fissures occurred in the wheel of the winding wheel, fissures present both on the hub, and on its spokes, which evolved in time in size and number. Similarly, at the level of the rotation reduction gear, damage occurred in time at the teeth of the toothed wheel, which are continuous, not cyclic, but which permanently evolved. Therefore, it was necessary to analyze the causes leading to the phenomena described in the above, also in view of establishing practical solutions to stop in due time the above mentioned phenomena.
Prezentation of the winding machine The winding machine itself is in the tower of the winding installation (Fig. a), with the Old Shaft with Skip,(the axis of the machine is at the level of the shaft +46,5 m) and it is destined to transport the useful mineral substance, the sterile and materials between two levels (loading station underground at level -320m, and dumping above ground level +21, 5 m). The part winding the cable is a multicable driving wheel. The type of the winding machine is MK 2,1 x 4(Fig. 2). The winding machine has asynchronous actuation. The winding installation is dynamically balanced(the balancing cable being heavier than the winding cable). The machine is actuated by two asynchronous motors(Fig. 3), with Pn = 2 x 500kW, with wound rotor, supplied at 6 kV. The transmission ratio of the 2TD-14 type reduction gear (fig. 4) is 6, the weight of the reduction gear without oil is 16060 kg, the oil volume in the reduction is 600 l. The size is 4000 mm length, 2300 mm width, 1790 mm height. Maximum number of rotations 750 rpm, maximum momentum on the main shaft 20 Nm, rotation direction reversible, number of steps 2. To reduce the shocks of the main reduction gear by 2 steps, 2 51 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
entries and 1 outlet, support springs were mounted. The helical springs on which the reduction gear of the winding machine is mounted have been sized for the maximum load produced when the transportation vessel is blocked on the shaft.
Fig.1. Winding installation ,, Old shaft with skip” Fig.2. MK 2,1 x 4 type winding machine
Fig. 3. Actuation of the winding Fig. 4. Reduction of the winding machine
The extreme loads of the reduction gear on spring are determined function of the magnitude of the extreme momentum of the reduction gear that occurs at the moment of blocking the transportation vessel along the shaft. At a major increase of the extreme momentum, one of the supports of the reduction gear moves down at the lowest point (to the support buffer), and the other moves upwards until the relaxation limit of the cylindrical helical spring. In this situation, the rotation momentum of the reduction gear is taken over by the helical spring that is compressed and the main shaft of the winding machine. At the modification of the rotation direction of the electrical driving motors, the loads change their values. To damp down the oscillations produced in the reduction gear by the momentum provoked by the electric motors, the reduction gear is provided with a buffer made up of a piston placed in a cylinder with oil inside. The rod of the piston is rigidly fixed to the brim of the reduction gear along the axis of the spring batteries (Fig. 5). The scheme of the. hydraulic buffer is shown in Fig. 6. Between the reduction gear and the main shaft there is a rigid coupling with bolts.
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Fig. 5. Battery of springs (1) and piston (2) Fig. 6. Buffer
Vibration and resistive electric tensometry measurements of the machine To determine the defects, vibration measurements have been done. The vibromechanical measurements have been have been performed with– 4371 type acceleration meters, made by Bruel & Kjaer, Denmark, - ICP, accelerometer Model 103.02-9 made by VibraSens France, Electronic vibrometer N2104 made by ICE Bucureşti, data acquisition has been made by SPIDER 30 and as acquisition soft CATMAN has been used, made by Hottinger Baldwin Messtechnic Germany, Fig. 7.
Fig. 7. Apparatus for vibrations Fig. 8. Kinematic scheme and measurement points
The investigation points are presented in Fig. 8, where the free bearing has been given number 1, the bearing next to the reduction gear has been given number 2, and the reduction gear noted R. In all the three points of measurements, measurements were performed in 3 directions, X(axial with the shaft of the driving wheel), Y(radial with the shaft of the driving wheel, horizontally), Z(radial with the shaft of the driving wheel, vertically). To determine the frequencies generated by the reduction gear, the formula in [3], page 354 were used. The kinematic scheme of the reduction gear is presented is shown in Fig. 8. Where z1=61 teeth, z2=113 teeth, z3= 41 teeth, z4=134 teeth. The inlet rotation in the reduction gear is 500 rpm. The reduction system(m), the spring package(k) and buffers(c) make a system of vibrations with a degree of liberty, Fig. 9.
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Fig. 9. Reduction system (m), package of springs (k) and buffers (c)
Frequencies generated by the gearing of the reduction gear at 500 rpm motor rotation are shown in Table 1.
Table 1. Frequencies generated by the gearing of the reduction gear at 500 rpm motor rotation Rotation n Freq. Position i rpm Hz Motor inlet 500 8,3 Z = 61 teeth 500 508 Step I 1 Z2 = 113 teeth 270 508 Z = 71 teeth 270 184,5 Step I 3 Z4 = 134 teeth 83 184,5 Motor outlet 83 1,38
Buffers play the role of reducing vibration levels close to resonance frequencies. For the given system, the analytical determination of this frequency is cumbersome. Experimental determination is much simpler. The accelerometer is placed on the reduction gear in position R vertically. The reduction gear is taken out of equilibrium, and it is let to vibrate freely. The acceleration level is recorded function of time. Fig. 10 shows acceleration measurements on the reduction gear verticallyat an impulse type excitation. The amplitude of the acceleration is in the range of -2 … 1,686 g.
Fig. 10. Accelerations on the reduction Fig. 11. Accelerations on reduction gear gear at an impulse type excitation vertically at an impulse type excitation 54 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
The peak to peak acceleration amplitude is 3,72 g. The time elapsed between two maximums is 0,083 s. The own determined frequency is 12 Hz. Fig. 11 shows acceleration measurements on the reduction gear horizontally, perpendicular to the motor, at an impulse type excitation. The acceleration amplitude is in the range of -0,372 … 0,306 g. The peak to peak acceleration amplitude is 0,678 g. The time elapsed between two maximums is 0,083 s. The own determined frequency is 12 Hz. Fig.12 shows measurements on the reduction gear horizontally axially with motors at an impulse type excitation. Acceleration amplitude is in the range of -0,9864 … 1.0424 g. Peak to peak acceleration amplitude is 2,029 g. The time elapsed between two maximums is 0,084 s. The own determined frequency is 12 Hz.
Fig. 12. Accelerations on the reduction gear horizontally axially with motors at an impulse type excitation.
As a result of the measurements performed, the values obtained have been synthesized as it follows: peak to peak speed and ASR measured on the winding machine are shown in Table 2, the peak to peak movement values and ASR measured on the reduction gear are presented in Table 2.
Table 2. Peak to peak speed values and RMA (average square root) measure on the winding machine Peak to Mark Measurement ASR peak Table point mm/s mm/s 4 1x 25,0 14,0 4 1y 13,0 6,6 3 1z 3,9 2,0 2 2x 80 42 4 2y 35 20 4 2z 7 3,5 2 Rx 34 18 4 Ry 18 9,6 3 Rz 74 37 4
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Tense-metric measurement were made with SPIDER 30 type apparatus, 1-LY11-6/120 type electrical resistant transducers, , and as data acquisition soft CATMAN utilitary has been used, made by Hottinger Baldwin Messtechnic Germania, fig. 12.
Table 3. Peak to peak movement values and ASR measured on the reduction gear Measurement Peak to peak ASR point mm mm Rx 1,3 0,7 Ry 0,9 0,5 Rz 2,5 1,3
Table 4. Vibration level according to VDI 2056, Group G heavy duty machines higher than300 kW V ASR Mark Obs. mm/s 2,28 ... 1,8 Bun 1 1,8 ... 4,5 Acceptable 2 4,5 ... 11 Still acceptable 3 11 ... 46 Inacceptable 4
Fig. 12. Apparatus for vibrations tensometry measurements
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Fig. 13. Transducer welded by the two halfhubs
In order to see the movement value along axial direction of the two half-hubs at the fissure occurred in the welding, a tense-metric transducer has been developed. The transducer is made up of a 10x10 mm and 410 mm long rod on which 2 electrical resistant transducers have been placed. The transducer has been welded by the two half-hubs fig. 13. By coupling the transducers to the tense-metric bridge, a series of measurement have been done, in the case in which the transducer was at maximum and minimum vertical position (12. and 6 o‘clock). The values measured in μm/m are shown in Fig. 14. The recording shows a 0,1 mm movements.
Fig. 14. Movement value between half-hubs
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Conclusions As a result of tensometric and vibration measurements, a series of conclusions can be drawn: Space between welding fissures between the two semi-hubs is 0,1 mm, which is confirmed from the calculations with finite elements. The reduction gear system‘s own frequency, elastic elements of buffer is 12 Hz. Maximum frequency generated by the reduction gear‘s gearing are are1,38 Hz, 8,3 Hz, 148,5 Hz, 508 Hz. These frequencies are for a rotation of 500 rpm of the driving motor. All frequencies increase from zero to maximum value, along with the increase of the motor rotation. Thus, frequencies generated by step I and II pass through resonance frequency of the reduction gear. The buffer plays the role of reducing to minimum the amplitudes around 12 Hz frequency. The 8,3 Hz frequency, the nominal rotation frequency is close enough to the 12 Hz frequency. The treaties of mechanical vibrations recommend for the working frequency to differ from the resonance frequency by ±20 %. In fact we have a percentage of - 44,5%.But this does not mean that there is no need for buffer. According to the level of vibrations according to VDI 2056, Group G > 300 kW on rigid foundations, the vibration level of the entire machine is over the admitted limit. According to ASR (average square root) in Table 2 it is seen that the higher vibration level, 37 mm/s is that of the reduction gear vertically. High vibration levels are met axially, intermediary bearing, 42 mm/s, with attenuation next to the free bearing, 14 mm/s attenuation due to the mass of the driving wheel. On the reduction gear an 18 mm/s vibration level is found. In the two bearings, radial vibrations are lower than axial ones, approximately twice. The buffers of the winding machine have great clearance in the articulations due to bolt holes becoming oval, which might have been conditioned by sleeving the bolt boring. Dumping shocks of the reduction gear when starting and stopping, due to buffer deficiencies, are transmitted to the teeth of the reduction gearing leading to its damage. To improve the functioning of the winding machine it is recommended in the first place to change the two defect buffers or repair them an consolidate the driving wheel to reduce elastic deformation of its shaft, in order to improve the functioning of the reduction gear. For comparison, vibration measurements have been performed on an identical winding machine in Livezeni Mining Plant. The vibration level of the winding machine in Livezeni Mining Plant, horizontally in the free bearing is 8,33 times smaller and on the reduction gear vertically 2,3 times smaller. Similarly, comparatively the level of movement between the two reduction gears, the one of Livezeni Mining Plant is 6,1 times smaller. Comparing the acceleration measurements on the reduction gear vertically at an impulse type excitation, it is noticed that in the case of the reduction gear in Livezeni Mining Plant, the movement is evenly slowed down, while the one from Lonea Mining Plant has a series of irregularities. These occur due to the deficient functioning of the buffers. Because of the buffers the gearing inside the reduction gear was destroyed. Thus high level vibrations occur, vibrations and shocks that can lead to damage of the system and fissuring of the driving wheel.
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References
[1] Gafițeanu, M., Crețu, S., Drăgan, B. Diagnosticarea vibroacustică a mașinilor și utilajelor, -Editura tehnică, București, 1989; [2] Kecs, W., W., Vibrațiile barelor elastice și vâscoelastice, -Editura Tehnică, București, 1996; [3] Ridzi, M., C., ș.a., Diagnosticarea vibromecanică a maşinilor şi utilajelor industriale, - Editura Militară, București, 2000; [4] * * *, Documentaţie tehnică, -E. M. Lonea, 2013; [5] * * *, Studiul privind funcţionarea maşinii de extracţie Puţ vechi cu schip de la E.M. Lonea, -C.A. nr.182/ 18.10.2013, E.M. Lonea;
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OPERATING THE OIL PRODUCTION FACILITY WITH SOLAR AND WIND GENERATOR
Conf. Dr. Ing. Marius STAN Universitatea Petrol Gaze din Ploiesti, e-mail: [email protected]
AbstractIn this paper we present an analysis of theoretical concepts very common nowadays, photovoltaic and wind turbines, but also a practical part where I presented a hybrid (photovoltaic-wind) to power a pump extraction cavitation progressive.
Keywords: photovoltaic; wind turbines; power; pump extraction
1 Introduction
Sun is undoubtedly a vast source of energy. In a single year, it sends to Earth 20,000 times the energy needed the entire population of the globe. In just three days, the earth receives from the sun energy equivalent to existing fossil fuel reserves. Solar energy is one of the potential future energy sources to be used permanently replacing conventional energy sources such as coal, oil, natural gas, etc., or to use them as an alternative to using conventional sources of energy especially during summer, the second use is currently the most widespread use around the world. Perhaps the most obvious advantage to its use, is to not produce environmental pollution, so it is a clean energy source; Another advantage of solar energy is that energy source that is based around the technology is free.
2. Achieving hybrid (photovoltaic-wind) system
A photovoltaic system (SFV) "converts solar energy directly into electrical energy based on photovoltaic effect, and bring it to the electrical parameters required by the consumer",[1]. The solar cells can be classified according to several criteria. The most commonly used criterion is that classifies cells after the thickness of the material. Here we distinguish cells with thick and thin cells. Besides the photovoltaic generator - cell, module or photovoltaic panel for efficient use of electricity and other components are necessary. For example, to compensate for the dependence of power generation of the solar radiation is required fallen in most of the electrical energy storage means or a battery. Its correct functioning implies a load control block. Adapting to the consumer electrical parameters of the PV generator requires either a DC-DC converter, DC-like either one, or both. In some situations "photovoltaic generator is coupled with alternative resources." All of these components, working together, constitute a system called photovoltaic system. PV systems fall into two main categories: -autonomous systems ( "stand-alone"), which supplies consumers connected to the public network adapter These systems are used in areas without electricity.
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In principle, "the energy produced by the solar panels is stored in batteries" and there is provided with an inverter (DC Converter - AC), 220V home users, Fgure 1.
a) b) Fig. 1 Photovoltaic systema) "stand-alone", b)"grid-connected",[11]
-autonomous systems, or connected to the public network adapter ("Grid - connected"). These systems are used in areas with electricity. In principle, the energy produced by the solar panels is fed into the national grid and simultaneously used for household applications. This can be achieved in various ways, but choosing the best components (quality inverter can increase production by 2% using the same materials) and the choice of appropriate installation technology are crucial, [3].
2.1.Electricity with photovoltaic system
Applicability Power produced by photovoltaic systems is useful in most applications including motors, pumps, electrical equipment and lighting. Not recommended the use of photovoltaic systems in water heating systems or premises (microwave, toasters can be used due to reduced working time). For these applications use dedicated solar systems (solar heating habitat), Figure 2. Unlike solar heat systems, shading in the case of photovoltaic solar panels can have an important effect in the evolution of the system. Some shading of solar modules provides partial protection by using a diode between each cell.
Fig. 2. Solar system independent consumer CC (DC), [13] 1 –photovoltaics, 2 - load control, 3 – Disconnect, 4 - fluorescent light (CC), 5 - TV, radio 6 - deep cycle
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Choosing voltage is determined by the size of the system. If small and medium systems, where most consumers are DC (direct current) or through a converter few are AC (alternating current) choice is simple - 12 V. Controller is the part that determines fully charge the battery without allowing overloading: prevents leakage of energy from the solar cell battery overnight, reduces battery deterioration by a total discharge, may present state of the system, short circuit protection. Converter,is the core component of an environmental system that converts low voltage DC current into high voltage alternating current (AC). The main feature is the device efficiency.
2.2 The wind turbine
Wind turbines for producing electricity can be used individually or in groups, called wind farms. Wind farms, which are now fully automated, ensuring, for example, 1% of California's electricity needs, 280 000 homes. Wind turbines but had some problems: large changes in wind speed causing variations in electric current and damage sometimes transmission systems; rotor blades collected while foreign substances, dust etc. reducing their yield, [4]. To measure wind speed and temperature can use the Data Logger is an electronic instrument that records data over time and correlated with the location of sensors and transducers in a given location, process, microprocessor-based programmable logic and displays on the display or transmits this data to a PC. Data Logger is used for data acquisition slowly varying sizes, with maximum acquisition of 1Hz are frequently reason not considered a real-time data acquisition. Data Logger processed data is stored on a flash memory or EEPROM main applications of this system are recording wind speed, temperature and humidity. Main blocks and system logic Data Logger for measuring wind speed and data processing using software programming HyperWare are shown in Figure 5.
3a 3b Fig. 3.Wind turbine 3a andData Logger wind speed measurement 3b
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A wind system, figure 3a, in terms of energy converts kinetic energy of wind into electricity.
3. Ahybrid renewable source of energy to power 10 kw
One of the most common applications of alternative energy is the power supply of a holiday home or cottage, located in an area without access to the public, but in view of developments in technology, hybrid systems may be successfully used in industrial fields. To supply a progressive cavity pumps can opt for power using photovoltaic panels or wind generators. Their combined use is always possible and the recommended due to the scope of use and relatively high power.
Fig. 4. The solar-wind hybrid system
To serve these consumers can use solar panels system must produce all electricity needs. These consumers need about 8 KWh per day for 7 days a week or can consider about consumption of 270 kWh / month. The system has a range of two days, that can provide the energy needed for 2 days even without any application of energy from photovoltaic solar panels and wind turbine. For this application we will need the following components,Table 1:
Table 1. To cover the consumption • photovoltaic solar panels; • 84 x 250W (21 KW installed capacity); • a wind turbine; • 1 x 10 KW Wind Turbine KIT; • group of batteries (rechargeable batteries) to • Charge 4 x Controllers Vario Track 80A; 12 V; • 3 x inverter Studer XTM 3500-48V; • battery charge regulator; • 1 x RCC-02 communication interface; • inverter DC (12V) - AC (220V); • 24 x Hoppecke 12V deep cycle battery with • energy saving lamps DC; 4700Ah; • equipment and connectors for assemblies. • 1 x 10kW inverter On grid SMA.
Where the electricity grid is near the pit extraction hybrid system can be networked, and once batteries will be charged at 100% it will inject networking excess energy that could be used at a later date due bidirectional meter. 63 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
If the national electricity network is at a greater distance of 300-400 m from the well location alternative energy supply is the most cost solution. To achieve hybrid system, shown above, it is not necessary to purchase 10 KW inverter ON GRID, but for safety (in case of failure of the hybrid system) can be installed a diesel generator with a capacity of 10 KW.
3.1. Operating the pump unconventionalPCP Renewable energy supply
The basic configuration of the surface driven PCP system illustrated in Figure 8 is the most common, although the drives downhole both hydraulic and electric and hybrid CFP various other systems are also available, [10]. Pump PCP probe is a positive displacement pump is composed of two parts: a steel "impeller" screw and a "state" composed of a rugged tubular steel with a sleeve of elastomer adapted properly to the configuration of the rotor. The stator is usually placed in the well, the bottom of the extraction column, while the rotor is connected to the bottom of the rod. Rotation of the rod by means of a drive system of the surface causes the rotor to rotate within a fixed stator, creates the pumping action required to bring fluids to the surface.
Fig. 5. Typical configuration of a system of progressive cavity pumping (PCP)
The hybrid system combines phase 10KW photovoltaic solar technology for energy by obtaining electricity using photovoltaic electric panels and wind turbines, producing energy from wind, [7]. The advantage of hybrid systems is that photovoltaic panels operate in parallel with wind and consumed electricity is stored in batteries of solar system. The system is sustainable and efficient the initial investment in a short time.10KW-phase hybrid system provides 40 kWh annual average daily production from solar panels, electric batteries can store 21.6 kWh and wind can produce 600Wh,wind 11 m / s. Pump cavitation progressive power from renewable sources will be achieved as follows: 64 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
Photovoltaic generator and windmill - convert the energy received from the sun and wind in DC electricity using photovoltaic effect and rotational movement of the turbine blades. The generators will generate voltage and current. Motor of the pump cavitation, however, require AC power. The photovoltaic system must therefore contain a converter c.c.- c.a., ie an inverter. Besides converting function, an inverter performs many other functions such as the intelligent component of a hybrid system.If the hybrid system is connected to the electricity grid National and electricity production is higher than demand operation of engine pump cavitation and batteries are charged, it will inject networking excess energy that could be used at a later date due bidirectional meter, [11]. If connecting to the national grid is not possible, alternative energy supply is the most cost solution. To achieve the hybrid system described above is not necessary to purchase 10 KW inverter ON GRID, but for safety (in case of failure of the hybrid system, [12] can be installed a diesel generator with a capacity of 10 KW.
Conclusions
Depending provided for energy, solar panels can be divided into photovoltaic panels that generate energy and solar thermal panels elective, which converts light energy into thermal one. Solar panels are one of the most popular alternative energy sources used to power systems and industrial. Small wind turbines play an important role in projects outside the network in locations where winds ensures economic energy supply, since alternatives such as diesel generators have a high cost of fuel when using continuous power supply. Photovoltaic solar panels and wind generators (hybrid systems) resulting electricity. The advantages of using solar panels and wind generators is represented primarily by the possibility of providing electricity in remote locations without access to mains electricity supply. Such a system is easy to install, requires no special knowledge in the field of energy, maintenance panels is easy (it only requires cleaning the impurities that attaches on their surface). Another considerable advantage of these systems is that they can expand in case of additional electrical consumers. Disadvantages: high cost of investment, geographical location axle hybrid system lowers yield incorrect installation panels and danger of destruction caused by weathering; increase disaster risks - panels and turbines are weathered.
References
[1] Ardelean Z., Captatoare solare, Editura Ştiinţifică şi Enciclopedică, Bucureşti, 1988 [2] Burghiu V., Energii neconvenţionale curate – vânt, soare, geotermie, biomasă, maree, valuri, curs litografic, USAMV, Bucureşti, 1998. [3] Drăgan V., Energiiregenerabileşiutilizareaacestora, Editura Atlas Press, Bucureşti, 2009 [4] Florescu Gh., Aventura surselor de energie, Editura Albatros, Bucureşti, 1981 [5] Ghergheleş V., Energia viitorului, Editura Mediamira, Cluj-Napoca, 2006 [6] Goetzberger A., Photovoltaic Solar Energy Generation, Editura Springer, Berlin, 2009
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[7] Maghiar T., Surse noi de energie, Editura Keysys, Oradea, 1995. [8] Silvestre S., Modeling Photovoltaic System Using Pspice, Editura Wiley,London, 2010 [9] Stoenescu G., Mecanică, Termodinamică, Electricitateşi Magnetism, EdituraUniversitaria, Craiova, 2001 [10] Temessl A.,Proiectarea şi construcţia instalaţiilor solare –Ghid informativ,Editura MAST, Bucureşti, 2008 [11] ***www.panosolare.com [12] ***www.pvcert.gr [13] *** http://petrowiki.org
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MODELLING OF THE GAS DIFFUSION IN FLEXIBLE PIPELINES FOR OIL & GAS PRODUCTION
Conf. Dr. Ing. Marius STAN Universitatea Petrol Gaze din Ploiesti, e-mail: [email protected]
Abstract This presentation describes a model used to study gas diffusion through layers of flexible pipes by time. The temperature gradient pipe is considered as temperature dependent permeability rates. This model is coupled with a calculation that indicate changes in pressure and volume of vapors resulting in the annular space. Associated mathematical models and methods for solving the results obtained are presented in Math Soft with a user-friendly interface that helps in data entry and processing results. In this presentation will show the possibilities of this software.
Keywords permeability; difussion; pipelines; polimer; riser
1 Introduction
The offshore oil industry, hoses and raizerele are made with polymers with internal and external coatings, which provides fluid flow through the inner and outer insulation in relation to the marine environment. These polymers have a certain permeability to gas that can facilitate the reduction of the potential damage mechanisms of the life of the steel layers located between the pipe and the outer shell of polymer. The destruction mechanisms associated with water condensation, therefore, they must be removed, [1]. A significant volume of oil resources is stationed in areas in deep water and very deep, the depth limit of the current work. The rapid development of methods for exploration and production in deep waters, registered in the last decade concludes that, once reached a record operating in deep water, it is immediately overcome.
2. Operating environment for flexible pipe and riser
They are considered deepwater activity in terms of oil, waters deeper than 400 m; 1 500 m is considered ultra deep water (over 1 600 m after MMS Mineral Management Service, USA) Oil industry operators are turning to large water depths, because there are significant resources that ensure high yields. Some oil wells in these areas can produce 8000 m3 / day crude oil production justifying additional costs and risk. Projects operating from premises situated in water depths of 2000 m in the Gulf of Mexico, Brazil and West Africa Offsore were unimaginable not long ago. A large number of wells have been drilled at depths of water; record of 10 400 ft (m 3174) was passed in February 2013 in the Indian Ocean. The most important aspects in production wells located in deep water depths are related to high water, but also on the bottom, the hostile environment in which it operates: waves 30 meters high; Winds exceeding 80 knots (148.2 km / h); low air temperatures: -15 ° C; Sea water temperature: 0 ° C; marine currents 3 knots (5.5 km / h) etc.
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Fig.1 Flexible pipes operating and production risers [3].
Column production or production riser is the portion that lies between the host plant surface and the seabed near the home of an installation depth. Discharge sizes are from 3 to 12 in (76.2 mm to 304.8). in diameter. The length of the riser is dependent on water depth and configuration of the column, which may be vertical or a variation waveform. Derivatives may be flexible or rigid and contained in the operating area of a fixed or floating platform installation type.
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3. Structure flexible pipe. General items
Unbounded flexible pipes over the last 30 years were a key component in the production of oil and gas offshore. They represent an alternative to rigid steel pipes where they have the advantage of a quick installation and the potential adaptation de route. These benefits often make unbounded flexible pipes, a more economical solution than rigid steel pipes. Successful exploitation of the majority of floating production systems depends on good performance systems dynamic flexible riser or jumper. The limits are consistently higher pressures and higher temperatures for deep waters, leading to increasing demands on the performance of pipe components. Layers of steel materials are decisive for their behavior in acidic environments static and dynamic applications. Unbounded flexible pipe structure requires that the steel is in direct contact with the fluid product. The medium is determined by permeation of small molecules (mainly H2O, CO2, H2 and CH4) by lining the polymer. Predictions therefore operating environment is a key issue for the prediction, design and service life of flexible pipes. Unbounded flexible pipes are made of concentric layers of polymer material and steel. In order to preserve the flexibility of the construction of the pipe layers are not bonded together. The following figure shows a typical cross section of a flexible layers depicting typical. Different types of flexible, [4], [5] unbounded pipe may omit some of the layers. It is presented in the most general description of each of the major layers, Figure 2.
Fig. 2 Deneral description of each of the major layers
Steel Carcass An interlocking layer made of a stainless steel strip. The casing prevents the collapse of the inner hull and provides mechanical protection against gear (pigging) and abrasive particles. Quality stainless steel structure is studied in detail, but is outside the scope of this paper research. Inner thermoplastic sheath A polymer layer extruded ensure the integrity of the internal fluid. Common types of polymers are polyethylene (PE), cross-linked polyethylene (XLPE), polyamide 11 (PA11) and Polivinilien fluoride) PVDF. Pressure armor layer A number of layers composed of helically wound wire form C of steel and / or metal strips. The layers of reinforcement provide resistance to radial loads.
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Fittings traction A number of structural layers consisting of helically wound flat steel wire. Layers are against and wrapped in pairs. The layers provide resistance to axial loads. External thermoplastic Sheth (A layer of extruded polymer) function is to protect steel components pipe from the outside (often seawater) and to provide mechanical protection. Nomenclature : PA11 polyamide 11:PE polyethylene: PVDF poly(vinylidene fluoride) C concentration (cm3/cm3): D diffusion coefficient (cm2/s)
4. Factors influencing the integrity and life of
Interior factors affecting the integrity riser are: fatigue fracture of steel casing, deformation housing, erosion figure 3a, influence of thermal variation, aging in action, chemical factor, temperature, diffusion in the annular space of H2S / CO2 figure 3b, fatigue protective coatings, the formation of hydrates. External factors affecting the integrity riser are: wear resulting from the interaction with the plant surface and submerged constructive elements, normal wear constructive materials, interacting with other lines submerged, deterioration protective outer covering Corrosion, hydrogen cracks action.
3a 3b Fig. 3 a)Damage to the outer covering contact with the production plant b)Explosion outer covering due to accumulation of gas in the annular space, [3]
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5. Gas diffusion – permeability
It is well known that polymeric materials can be regarded as watertight only to a certain extent. With a difference of partial pressure of a fluid in a polymer membrane (liner) will result in higher penetration fluiduluide pressure to low pressure. The mechanisms of permeation polymers are outside the scope of this work are described extensively in the literature. Flexible pipe, coatings characterized by migration of gas permeability inside the pipe and the outer casing annulus. The offshore oil and gas production of molecules of interest are significant and methane (CH4), carbon dioxide (CO2), hydrogen sulfide (H2S) and water (H2O), [2]. Manufacturing companies arealizat research programs in order to determine the characteristic phenomenon of diffusion constants: permeability diffusion coefficient, solubility, the polymers used as material for deconstruction to flexible pipes. In addition to the main layers, are included more polymer layers to prevent wear between the structural layers. The strips of insulation with a low thermal conductivity may be used, for example, between the main reinforcement and the outer jacket, in order to obtain specific properties of the pipe insulation.
Fig. 4 The model of an element wire, [2]
Understanding the damage mechanisms in polymer coatings during gas decompression goes through the knowledge of gas transport phenomena in polymers, by studying the influence of gas absorption on material properties, and by modeling the behavior of the material during a decompression. The mathematical theory of diffusion (Crank, 1968) in an isotropic system is based on the hypothesis of the proportionality between the scattering flux of the molecules (which is the quantity of species crossing a membrane per unit time and surface) and the concentration gradient between the two faces Of the membrane. It is Fick's first law [2]:
(1)
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J is the scattering flow of the molecules D - diffusion coefficient (cm2 / s); D = D (C, T, p) C – concentration The permeation, [4]. [5] Table 1, of methane and carbon dioxide plasticized polyvinylidene fluoride water (PVDF) and plasticized polyarnid 11 (PA11) was measured for a number of temperatures and pressures with testing devices. Table1
5a 5b
5c Fig. 5 Numerical simulation for a) difussion CH4, b) difussion CO2, c) difussion H2O
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Conclusions Ventilation To avoid gas diffusion effects in terms of maintaining balance in corrosive environment created by their penetration is required ventilation gas in the annulus. Establishing the ventilation status of layer fluids and observing the conditions considered to limit the upper end: continuous ventilation or - Intermittent respectively at atmospheric pressure ventilation or - sub-atmospheric (vacuum). Relationships and mathematical equations of the model proposed for the analysis and design of ventilation for independent parameters of time (geometric) while those for addicts (hydraulic parameters). works constitute a separate objectives.
References
[1] Eugene Sas , Jean Marie Pere , Pierre Savy , Ahmed Omar Flexible Pipe Design Optimization for West Africa Deepwater : Agbami Production Riser Case Study, Offshore Technology, 5-8 May, Houston, Texas, 2008 [2] Benjelloun Z.-Dabaghi1and A. Benali, Mathematical Modelling of the Permeation of Gases in Polymers,1 Institut français du pétrole, 1 et 4, avenue de Bois-Préau, 92852 Rueil- Malmaison Cedex – France, Oil & Gas Science and Technology – Rev. IFP, Vol. 56 (2001), [3] Lazăr Avram, Claudiu Tănasă,. N, N. Antonescu, Marius Stan, Valentin Tudorache, Asupra proiectării coloanelor de raizere şi criteriul de selecţie a acestora, cnr- cme.ro, FOREN 2016 [4] ***ANSI/API 17J ―Specification for Unbounded Flexible Pipe‖ 3, Edition, 2008 [5]***ANSI/API 17B ―Recommended Practice for Unbounded Flexible Pipe‖ 3, Edition, 2009.
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THE FOURTH INDUSTRIAL REVOLUTION „INDUSTRY 4.0”
Alin STĂNCIOIU* * Lect. dr. eng. U.C.B, Tg-Jiu, e-mail [email protected]
Abstract: The many observers estimate that in the world is at the beginning of a new industrial revolution, which it is considered the fourth revolution and it is called "Industry 4.0". The connecting many products to the internet, presence of sensors, wireless communications expansion, robot and intelligent machine development, real-time data analysis have the potential to turn the way the production is done. Connecting the physical world to the virtual world in cyber-physical systems it will have a disruptive impact on technologies, manufacturing processes and people.
Keywords: revolution, industry, internet, cloud computing
1.Introduction. The industrial companies in all sectors globally are going through a fourth industrial revolution that could be called "Industry 4.0". The transition to this new reality of the digital industry is in full swing all over the world: approximately one third of companies are already measures the digitization as high, and this level is expected to rise on average from 33% to 72% in the next 5 years.
Fig. 1 The industry evolution
2. What it is Industry 4.0 It is a significant transformation of the entire industrial production by merging digital and internet technologies to conventional industry. Opinions are divided on the use of terms of revolution or evolution. In Europe, the concept was launched and it is supported by Germany government programs and leading companies like Siemens or Bosch. In America, the approach is often called "Smart Manufacturing" in China discusses the "Made in China 2025" and Japan "Innovation 25". 74 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
All aim the development of an industry to launch products faster to increase flexibility and increase resource efficiency through digitization. In intelligent factories created by Industry 4.0, modularly structured, cyber-physical systems monitor physical processes, create a virtual copy of the physical world, and make decentralized decisions. They communicate using the Internet of Things, cooperating in real time with each other and with human resources.The information storage and processing takes place using Cloud computing. The Cyber-physical systems The Cyber-physical systems SC-F mechanisms monitored or controlled by algorithms (software) integrated with users via the Internet.Physical and software components interpenetrate on different spatial and temporal scales, having multiple and distinct behaviors and interacting in ways that change the context of the whole system. Example of SC-F: intelligent vehicle systems, medical monitoring, process control systems, robotic systems, autopilots in avionics, smart homes, intelligent transportation, smart cities, etc. Multidisciplinary approach involving SC-F have the same basic architecture as the IoT, but greater with filler and coordination between physical and computational components. Internet of Things IoT (also called the infrastructure of the information society) describes interconnection of intelligent components (uniquely identifiable and interoperable), whether physical devices, vehicles have buildings elements have electronics, software, sensors, actuators and components for connecting to a network that allows collecting and exchanging information. The intelligent items can thus be remotely monitored and controlled, allowing integration between the physical world and computerized systems. Estimate of 50 billion intelligent items in 2020. Sensors and actuators make from IoT an instance of SC-F. IoT uses machine learning capacity and technology for Big Data for retrieve, interpret, and use data from the automation sensors and systems industry. Cloud computing Using shared (common) on request by computers or other devices of sets of data and computing resources (processing) on the Internet.
3.The Industry Technologies 4.0 The large industrial revolution depends on small technological revolutions in the various fields: . Applying information and communication technology to digitize and integrate information systems in design, development, manufacture and use. . New software technologies for modeling, simulation, virtualization and the digital manufacturing. . Development of cyber-physical systems to monitor and control physical processes. . The evolution of 3D printers and additive manufacturing to simplify manufacturing. . Support for the decision to human operators, smart appearance and support tools using augmented reality. New forms of human-machine interaction. Many of these technologies have been available for a few years, and others are not yet ready for use on a large scale
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4.The benefits of Industry 4.0 TIME: Every employee becomes more efficient when working in an optimized process. Engineers spend 31% of working time searching for information, time that can be used for activities that produce value. COST: Presents accurate data in the right context and format needed to make informed decisions. Incorrect information and erroneous decisions taken on them cost 25% of the company's income. FLEXIBILITY: They create flexible systems ready for change and ready for new opportunities. Only 36% of companies are ready to optimize processes based on data analysis. INTEGRATION: The digital manufacturing involves the simultaneous development of the product and the production process. The companies reduce 80% time with production interruptions if they use digital validation. The digital factory The Digital Factory will allow optimization of all phases in the product life cycle. The virtual simulations of design and functionality developed in parallel with manufacturing planning lead to a much faster market launch, significant cost reduction and the higher quality. Everything will be driven by data analysis. Digital Factory integrates Product Lifecycle Management solutions, Digital Manufacturing, Manufacturing Execution System and IoT components that communicate feedback from you manufacture with ongoing processes or products in use. The workplaces in the Industry 4.0 The future of blue dressing gown will be seriously influenced by the Industry 4.0. The surely the skills required in the factories of the future will be other than the present ones. Many of today's activities, serving production machines, precision positioning, assembly, quality inspection will be done by robots. Not only are they more effective, they also communicate perfectly with decision and control systems. The labor market will change, but it is hard to predict if there will be more or fewer jobs overall. Robots are still at the beginning and can not replace people in all activities. On the other hand, the rate of return on investment in a fully automated factory is not attractive now. All forecasts are based on historical data, but exponential technologies are completely new, so the effect of large-scale evolution and use is hard to predict. The risk is to have massive unemployment for certain categories and the lack of digital skills.
5. The Romania's advantages in terms of Industry 4.0 There are many factors that place our country in a very favorable position in the prospect of moving to Industry 4.0. Even though there are voices claiming that we can not make the jump from 2.0 to 4.0, Romania will benefit of significant and will attract numerous investments. I mention below 7 advantages that Romania has: 5.1. Industry Strategy 4.0 aims to bring production back to Europe, focusing on personalized production, high quality and manufacturing near the consumer market. Eastern European countries are the best destinations for investing in new production facilities.
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5.2. The automotive industry will be the one to engage most resources and make the most investments.In fortunately in the last 10 years, this industry has developed strongly in us. The number of automotive suppliers in Romania is steadily increasing. Even if we have only two car makers, Dacia and Ford, the supplier network is well developed. Of the top 20 global automotive suppliers, 13 are present in Romania with production facilities. According to ACAROM, the turnover of suppliers is twice as high as the builder's. 5.3. The speed of the internet connection in Romania is one of the highest in Europe. The Internet of Things will generate a huge amount of data and will require very high transfer and processing speeds. 5.4. IT companies will have an increased involvement, Industry 4.0 will attract new cyber-physical systems (CPS) services or services: IT security, Big Data analysis, M2M solutions, and Artificial Intelligence. The IT sector is well developed in Romania and can support investors' efforts in digital factories. 5.5. The skills required for the digital factory can be found in Romania. There is a good manufacturing tradition and good technical universities, as evidenced by the numerous investments in Automotive R & D. 5.6. In the period 2016-2020 are numerous grant programs for R & D Technologies Industry 4.0. They will support the development of Romanian companies and it will attract investors. 5.7. Germany is the main supporter of Industry 4.0 strategy and is one of the largest investors in Romania.The many German companies already have the latest technology in production facilities from us.
6.Conclusions: There are significant opportunities for development for Romania in the context of Industry 4.0. The direction in which the industry goes is very clear. Data management and security will be key issues to solve. To achieve the true Industry 4.0 potential, companies need to plan digital transformation. Although worldwide companies are advancing in Industry 4.0, the study reveals some regional features at the level of objectives: Japan and Germany are implementing digitization primarily to increase their efficiency and product quality. In the US, the trend is to develop new business models using digital offers and services, and to provide these products and services digitally as quickly as possible. China's manufacturing companies focus on ways to cope with international competitors by cutting costs. "Our study shows that the level of digital integration will be broadly comparable between regions over the next five years, led by countries like Japan, Germany and the US. We do not expect Industry 4.0 to divide regions, but to create a strong link between companies and countries, and thus even promote globalization. Data analysis tools enable product development and also allows companies to expand services and better align their offerings with the needs of their clients
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References: [1] Hermann, Pentek, Otto, 2016: Design Principles for Industrie 4.0 Scenarios, accessed on 4 May 2016 [2] Jump up^ Kagermann, H., W. Wahlster and J. Helbig, eds., 2013: Recommendations for implementing the strategic initiative Industrie 4.0: Final report of the Industrie 4.0 Working Group [3] Jump up^ Heiner Lasi, Hans-Georg Kemper, Peter Fettke, Thomas Feld, Michael Hoffmann: Industry 4.0. In: Business & Information Systems Engineering 4 (6), pp. 239-242 [4] BMBF-Internetredaktion (2016-01-21). "Zukunftsprojekt Industrie 4.0 - BMBF". Bmbf.de. Retrieved 2016-11-30. [5] Tom Savu - From the Industrial Organization to the Digital Organization - Opportunities for Development and Adaptation of Faculties, Annual Meeting of the Deans of Technical Universities in Romania, U.P.B., 2016 [6] http://smarternext.com/ro/2016/05/09/industry-4-0-romania/
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ASPECTS CONCERNING THE IMPLEMENTATION OF A METHODOLOGY FOR DETERMINING THE COLUMNS DIAMETERS OF GUIDING A PRESE - (Part I)
Lecturer PhD Eng. RĂDULESCU Constanţa University ,, Constantin Brancusi‟‟ from Targu-Jiu, ROMANIA, [email protected] Professor PhD Eng. CÎRŢÎNĂ Marius Liviu University ,, Constantin Brancusi‟‟ from Targu-Jiu, ROMANIA, [email protected]
Abstract: In this paper we present a methodology for determining the value of the diameters of the guide column of a press which has a construction with closed frame. For determining these values is necessary to go through several stages namely: the simplified representation of the press, the representation the forces requesting the four columns, the determination the values these forces, the determination of maximum bending moment, and finally. by obtaining a determined static system and using the Mohr-Maxwell and rule Veresceaghincan get columns diameter values.
Keywords: guide columns, the forces requesting, static system
1. INTRODUCTION It is known that the design represents a creative activity difficult, in which you must combine imagination and aesthetic sense with determination the rational calculation of lawfulness the physical phenomena and economic. For to reach a rational calculation it is necessary to start design to respect the modeling phase of the piece and, in some cases, the subassembly or the assembly from which it makes part. The modeling problem is put from two points of view [1]: the adoption of a simplified form of the piece; the schematization of the mechanical loads that are applied on the piece. Alongside of the phase of the establishing the model of resistance calculation, another important stage in the stage of designing and dimensioning is that of choice of the material the piece. The choice of material is influenced by many factors such as: resistance characteristics (the breaking strength, yield strength), elastic properties, characteristics related to the environment of use the piece / the machine); characteristics linked to the methods and processes for obtaining semifinished products etc. In this paper we present an calculating algorithm that help us at the correct determination of the diameters of the column of guide for a press having the construction with closed frame. On this press can be realized operations of plastic deformation: free forging, stamping, embossing, cutting, calibrating, extrusion, straightening, etc.
2. FORCES FROM GUIDES Taking into account aforementioned indications, in figure 1.1, it is presented simplified schem a press having the construction with closed frame with column of guide[3]. Resistance structure of the machine is formed by two fixed sleepers (the upper traverse and the lower traverse) and four columns that are considered four columns are considered as some bars 79 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
embedded at heads in the two fixed traverses, the ram causing the their charging with the forces from guides [6].
Fig.1.1. The construction with closed frame with columns of guide.
Forces from guideways are characterized by the fact that varies proportionally with the deformation force, and their point of application are changed due to the movement of the ram for carrying out the working stroke. At the same time, columns are requested at tension due to the forces from the fixed traverses [2]. The material they are made of columns can be a carbon steel of quality, improved OLC 35, OLC45, OLC50, OLC55, OLC60 (C35, C45, C50, C55, C60). Taking into account the requests mentioned, the maximum tension from the column can write that sum the tensions due to each request in part namely:
4FMtk 32 i max 23 a 1.1 ddkk where: Ftk – the total tensile force from the column; Mi – the bending moment due to the forces of the ram guides; dk – column diameter (in dangerous section); σa – admissible tension at the traction request to the symmetrical alternating cycle of the column material. Specific requests for presses with traverse, frameworks with columns se vor determina will be determined based on loading schemes under the condition of an eccentric load applied. For this purpose, it is considered the admitted limit for maximum eccentricity and which, in general it represent a value:
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eHmax 0,1 l [mm] 1.2 where: Hl - represent the total stroke of the plunger. How the machine is designed to emboss the deep pieces of the revolution, the molds must be symmetrical and the center of force coincides with the geometric center of the mold. In this situation, it is very easy to place the mold on the machine table such that eccentricity ,,e,, is zero. There may, however, be situations where this thing is not realizing, Either due some die placement errors the molds, either because they can perform several pieces simultaneously and their arrangement does not allow the placement of the application point of resultant the pressing forces on the geometric axis of the press. In view of these considerations, we can say that it is necessary to choose a value of eccentricity. To determine the forces acting on the columns use calculation schemes that depend on how the piston rod is attached to the ram. At four-column presses, the tensile force in the most requested column, with the point of application of the force as in fig.2, is calculated with the relation:
Feax2 2ey Fk 11 1.3 4 ab where: Fa - pressing force;
ex - the projection on the Ox axis of eccentricity ,,e,,;
ey - the projection on the Oy axis of eccentricity ,,e,,; a - the opening between the axes of the axes in the direction of the Ox axis (left-right); b - the opening between the axes of the axles in the direction of the Oy axis (front and rear).
Fig.1.2. The layout of the eccentric force application point P towards the geometric center O in the working plane of the machine.
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As can also be seen from the loading schemes of fixed traverses, in the case represented, the column 3 is the most requested and must withstand at the force Fk expressed through the relation 1.2. Between the two components of eccentricity ,, e ,, there are, as is apparent from fig.1.2, relation: 2 2 2 exy e e 1.4.
From the maximum function condition Fk(ex,ey) (derivative of the first order equal to zero) and the restriction given by relation 4, the values will be determined: ex și ey . It results in a maximum possible value of the traction force in the column Fkmax [N], by replacing its values , and of the pressing force in the relation 1.3. The total force in the most requested column ( F ) it determined by summing up the tk exploitation force F with a remanent force of tightening F , necessary to maintain in kmax rk contact, components parties of the press at maximum requeste:
F F F [N] tk kmax rk (1.5) Due to the constructive and functional conditions it is sufficient to appreciate the size of the remaining force with the relation:
F 0,1F (1.6) rk kmax
So it can be written: F F 0,1 F 1,1 F [N] (1.7) tk kmax kmax kmax
After determining the forces demanding the press columns, It will be possible to determine the maximum bending moment acting in the embedding of the column in the two traverses.
3. CONCLUSIONS For determine the values diameter of the columns of the press, for beginninghas been presented simplified schema of machine from where it could observe The resistance structure which is format of two fixed traverses and four columns of guiding. Then they were represented, on drawing, the forces acting on the columns. The forces in the guides are characterized in that it varies in proportion to the deformation force, and their point of application changes due to the displacement of the slider for execution the working stroke. Also, the columns are required to stretch due to the forces in the fixed traverses. Considering all this, it was possible to determine the total force in the most requested column.
4. REFERENCES 1. Gh. Buzdugan. s.a. – Calculul de rezistență al pieselor de mașini - Editura Tehnică,Bucuresti, 1979 82 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
2. C. Dumitras, s.a – Stante si matrite din elemente modulate, Editura Tehnică Bucuresti,1980. 3. Cirtina L.M., Radulescu C.,- Calculation algorithm necessary for d esigning and sizing the chassis in a construction welded from the material S275jr2g3 (Part I) –14-15 noiembrie, Confereng 2014, pag. 88-92, Analele Universitatii ,,Constantin Brancusi,, din Tg- Jiu ISSN 1842-4856. 4. A. Ripianu, s.a. – Mecanica Tehnica – Editura Didactica si Pedagogica Bucuresti, 1979 5. Al. Stoenescu, s.a – Mecanica teoretica - Editura Didactica si Pedagogica Bucuresti, 1963 6. Radulescu C., Cirtina L.M., - Studies on machine parts made of welded construction –Revista de Durabilitate si Fiabilitate, nr.1 din 2016, Tg-Jiu
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ASPECTS CONCERNING THE IMPLEMENTATION OF A METHODOLOGY FOR DETERMINING THE COLUMNS DIAMETERS OF GUIDING A PRESE - (Part II)
Lecturer PhD Eng. RĂDULESCU Constanţa University ,, Constantin Brancusi‟‟ from Targu-Jiu, ROMANIA [email protected]
Abstract: In this paper we present a methodology for determining the value of the diameters of the guide column of a press which has a construction with closed frame. For determining these values is necessary to go through several stages namely: the simplified representation of the press, the representation the forces requesting the four columns, the determination the values these forces, the determination of maximum bending moment, and finally. by obtaining a determined static system and using the Mohr-Maxwell and rule Veresceaghincan get columns diameter values
Keywords: guide columns, the forces requesting, static system
1. DETERMINATION OF MOMENTS For determine the moment of bending Mi which appears in the relation 1.1 and which represent the maximum bending moment which acts in the posts of the column in the two traverses, we consider the column that a straight bar of equal section, embedded at both ends, aded with a bending moment M generated by the ram's action on it at the point where the pressing force has the maximum value, fig.2.1.a. The moment M is produced by the eccentricity,,e,, of the pressing force from the vertical geometric axis of the machine (Oz) and can be expressed through the relation:
Fea M [Nmm] 2.1 4 How static system from fig.3.a is undetermined is replaced by one of a embedding with two requests (cutting force and bending moment) with the unknown sizes noted with X1 şi X2, in this way a determined static system called basic system is obtained (fig.2.1.b) in which care X1 and X2 constitute the unknowns of undetermined static. By neglecting the action of the column's own weight on the embeddings, the request much lower than the others, thus eliminating from the calculations a third unknown of undefinite static. Then, it write the equations under condition which expresses that the base system has the same deformations as the undefined static system [4], [5]. To write these equations we use the Mohr-Maxwell method and the Veresceaghin rule:
11XX 1 12 2 10 0 2.2 21XX 1 22 2 20 0
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Fig.2.1. Determinarea momentelor
Its are being built diagrams of moments M0 for the system loaded with the given tasks (fig. 2.1.c), diagram of moments m1 (fig.2.1.d) for a load equal to the unit applied in the point and direction of the unknown static undetermined X1 and the diagram of moments m2 (fig.2.1.e) for a moment equal to the applied unit in the point and in the sense of unknown static undeterminate X2.
2. TRANSFORMATION OF THE BASIC SYSTEM IN A STATIC SYSTEM DETERMINED
The expressions displacements ij from canonical equations 2.2 can be calculated as follows: 1 M0 m dx aa0 EI 1 M02 m dx 2.3 ai EI a 1 M0 m m dx aj EI a j 0 The equations of moments M , m1, m2 according to the diagrams in fig. 2.1.c,d and e will can write:
M, x 0, z1 M 0 0,x z1 , h m x h, x 0, h 1 2.4 m2 1, x 0, h
Then:
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h h h 1 12 1 m2 dx x h dx x 2 2 hx h 2 dx 11 1 EI0 EI 0 EI 0
h h h 3hh 2 3 12 2 1x x 2 h 1 h x dx 22 h xdx h dx h h x EI EI3 20 EI 3 0 0 0 00
11hh m m dx h x dx 12 21 1 2 EI00 EI
hh 2h 2 2 1 1h x 12 h 1 h h dx xdx h x h EI EI0 2 EI 2 EI 2 00 0 hh 1 1 1h 1 m2 dx dx x h 22 2 0 EI00 EI EI EI 1hh 1z1 1 z 1 z 1 M0 m dx M x h dx 0 dx M xdx Mh dx 10 1 EI0 EI 0zz EI 0 11 2.5 2 z1 2 1x z1 1zz11 1 M h x M z11 h Mz h EI20 EI 2 EI 2 0
h z1 1 1 1z 1 Mmdx0 Mdx () Mx1 Mz 20 20 1 EI00 EI EI EI
Replacing the values ij obtained in canonical equations 2.2, obtain: 323232 1hh11hhhh 1 1 1 1 1z zz1 X X X X Mz Mz1 h 1 0 h 0 1 X11 2 X 2 2 1 Mz 1 1 h 0 EIEIEI333 EI 2EI 2 EI EI EI 2 2 2 2 2 1h11hh2 1 1 1 1 1 X1 XX1 h X 2 h X 2 Mz 1 Mz0 Mz 1 00 EIEIEI2 22 EI1 EI EI 2 EI 1 2.6 or:sau sausau 2 2 hh2 z1 hhXhh X Mz 10 zz1 1X 2 X 1 Mz 10 1 3X 211 X 2 Mz 12h10 33 2 2 2hh 2 h 22 hXh1 h X 2 Mz 1 0 2 XX11 h h X 2 Mz 1 0 de unde22 : 2.7 wherede defrom: unde unde :: 66MMzz11 X1 66 66MMMM11 zz u u h h1111 h h XX11 11 u u u u h h h h zzh h h h X M 113 2 M u 3 u 2 2 zzzz Xhh M 11113 2 M u 3 u 2 X22 M 3 2 M u 3 u 2 hhz 2.8 unde am notat u 1 Where we noted u=zh/h z1 undeunde am am notat1 u 1 86 h Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
The base system from fig. 2.1.b turns into a determined static system, fig.2.2.
Fig. 2.2. The transforming the base system into a determined static system
6M F X u1 u 2.9 21h
M22 X M u32 u 2.10
The reactions F1 și M1 from point 1 can be determined of equilibrium equations of forces and moments: 6M F0 F F 0 F F u 1 u 1 2 1 2 h 1 M00 M1 M M 2 F 2 h 2.11
M1 M M u3 u 2 6 M u 1 u
M1 M1 u 1 3 u
If we consider that, average, maximum stamping force has maximum At a third of the h z race from of the lower dead point, then it follows that z , so the report u 1 0,5. 1 2 h Replacing in relations 2.10 and 2.11 moment values are obtained M1 și M2.
The maximum bending moment of the column embedding is:
MMMMi max 12 , 0,25 2.12 or using the relation: Fe M a 0,25 2.13 i 4 87 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
The replacement of traction force values Ftk and bending moment values M i thus determined in the relationship 1.1 obtain:
4FMtk 32 i 23 a 2.14 ddkk By replacing known elements a third degree equation will be obtained which can be solved by numerical methods, thus obtaining the diameter dk. Taking into account the value calculated of minimum diameter required dk, we can choose the value of the thread size from the ends of the columns, well as the guide diameter in the fixed traverses.
3. CONCLUSIONS For determine the values diameter of the columns of the press, for beginninghas been presented simplified schema of machine from where it could observe The resistance structure which is format of two fixed traverses and four columns of guiding. Then they were represented, on drawing, the forces acting on the columns. The forces in the guides are characterized in that it varies in proportion to the deformation force, and their point of application changes due to the displacement of the slider for execution the working stroke. Also, the columns are required to stretch due to the forces in the fixed traverses. Considering all this, it was possible to determine the total force in the most requested column And then the maximum bend moment was determined from column embedding. This is determined by the transformation of the base system into a determined static systemt by writing the equations using the Mohr-Maxwell method and the Veresceaghin rule. By determining traction force and bending moment, in end we will arrive at a grade III equation that can be solved by numerical methods, thus obtaining the diameter the guide columns.
4. REFERENCES 1. Gh. Buzdugan. s.a. – Calculul de rezistență al pieselor de mașini - Editura Tehnică, Bucuresti, 1979 2. C. Dumitras, s.a – Stante si matrite din elemente modulate, Editura Tehnică Bucuresti, 1980. 3. Cirtina L.M., Radulescu C.,- Calculation algorithm necessary for d esigning and sizing the chassis in a construction welded from the material S275jr2g3 (Part I) –14- 15 noiembrie, Confereng 2014, pag. 88-92, Analele Universitatii ,,Constantin Brancusi,, din Tg-Jiu ISSN 1842-4856. 4. A. Ripianu, s.a. – Mecanica Tehnica – Editura Didactica si Pedagogica Bucuresti, 1979 5. Al. Stoenescu, s.a – Mecanica teoretica - Editura Didactica si Pedagogica Bucuresti, 1963 6. Radulescu C., Cirtina L.M., - Studies on machine parts made of welded construction – Revista de Durabilitate si Fiabilitate, nr.1 din 2016, Tg-Jiu
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RESEARCH ON DEGRADATION CORROSIVE ENVIRONMENT OF SOME STEELS USED IN MANUFACTURING MINING EQUIPMENT. MECHANICAL TESTS
Lecturer PhD. eng. Florin CIOFU, Engineering Faculty, ‖Constantin Brâncuşi‖ University, [email protected] Lecturer PhD. eng. Alin NIOAŢĂ, Engineering Faculty, ‖Constantin Brâncuşi‖ University, [email protected]
Abstract: Simultaneous action of mechanical stress variables and the corrosive environment leads to the deterioration of structures made of steel or of other metallic materials, a process called fatigue in corrosive environment or corrosion fatigue, which has causes and effects different from degradation under the singular action, either of mechanical strain or of corrosive environment. The aim of this paper is the study of the behavior,under fatigue conditions in corrosive environment of low alloy steels meant for the construction of mining equipment used in various mining operations in Gorj county. Based on experimental research regarding sustainability in fatigue corrosion, analyses of the interaction between the mechanical and the electrochemical factors as well as microscopic analyses of the structures we aim in this paper at deeply studying the performance of degradation processes that occur in the surface layers and lead to destruction by corrosion fatigue of the steels under study.
Key words: degradation, corrosion, strength
1.INTRODUCTION Degradation of a material is characterized by any change in its state relative to its original condition. Making the structural analysis by the designer requires knowledge of induced stresses in the components materials, of modes of degradation during manufacturing and use. A study made by the American Society of Civil Engineers has determined that 80- 90% of the damage occurring in steel structures are caused by processes of fatigue, representing a process of side cumulative breakage caused by cyclic variable loads. If the fatigue phenomenon occurs in the presence of an aggressive environment, this type of degradation is known as the corrosion fatigue. The degradation through corrosion may reduce the strength to fatigue of the material as it shrinks during the initiation of fatigue cracks on the surface of the material [1]. All the materials based on Fe, Al, Ti, Cu or other ferrous or nonferrous metallic materials, are liable to this way of destruction. Fatigue in corrosive environments raises special economic and technical issues in the consequences they can cause as a result of accidental damage of the constructive elements in the structure of the machines and installations in various industrial fields.
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2.EXPERIMENTAL METHODS USED 2.1. Materials under study The steels for the structures of surface mining equipment are used either in welded construction or assembled by rivets or screws and are chosen from the category for general use STAS 500 / 3-80 constructions, respectively AFNOR / A36101 A35501 EURONORM 10025. For the main components of metal construction excavators are used thick steel sheets whose technical delivery conditions are specified by ISO 15608 CR SR: 2002. Compared to steels for general use in the SR CR ISO 15608: 2002 standard are indicated two steel brands, OL 37 4k (E24 - 4) and OL 52 4k (E36 - 4) having improved chemical composition, mechanical and technological properties in the sense of increasing the weldability properties of the material. The improvements relate primarily to limiting the sulfur content, on product at 0.030% for OL 37 4k (E24 - 4) and at 0.020% for OL 52 4k (E36 - 4) as compared to 0.045% of STAS 500 / 3-80.The OL 4k 37 (E24 - 4) steel brand is deoxidyzed with silicium and aluminum and the steel 4k 52 OL (E36 - 4) one with silicium, aluminum and titanium. For reducing the phenomenon of lamellar teasing, the sheets of OL 4k 52 (E36 - 4), more than 20 mm thick, used for the required elements in its thickness direction must also comply with the conditions of Z 15 quality class, according to EN 10002-1 : 2002. Also for the sheets of OL 4k 52 (E36 - 4) brand, the value of the equivalent carbon computed on liquid steel formula is guaranteed with formula [2]:
(1)
General purpose steels used for making metallic structures have a low percentage of carbon , not exceeding 0.25%. Steel mark is defined generally according to the minimum value of tensile strength, as evidenced by a system of notation indicating: -The domain of steel, specified by a literal symbol, ie general use OL-steel for construction, delivered as plastically deformed products in hot working in laminated semi - finished products and forged bars. -Minimum tensile strength in daN/mm2 for general purpose construction steels (OL), cast steel (OT) and steel for pipe (OLT). - Quality class, marked by numbers from 1 to 4, indicates the chemical composition and the mechanical strength and technological characteristics guaranteed on steel delivery. 2.2. Mechanical and chemical composition of steels under study E36 steel is used in construction of mining equipment, especially in manufacturing porters in the central area, tower and arms of heavy excavators. The main mechanical characteristics and the chemical composition of this steel are shown in Tables I and II.
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TABLE I. Mechanical characteristics of E36 steel (according to STAS 8326-86) Material Mechanical characteristics 2 2 σr (N/mm ) σc (N/mm ) Elongation at break (%) E36 steel 559 460 23 where: σr =tensile strength, σc = flow limit
TABLE II. Chemical characteristics (share %) of E36 steel (according to STAS 8326-86) Chemical compostion (%) Chemical compostion (%) C 0,18 Cu 0,01 Si 0,28 Ni 0,01 Mn 1,5 Cr 0,01 P 0,018 Mo 0,002 S 0,008 Nb 0,04 Al 0,03 B 0,0001 Ti 0,004 Ca 0,0001 V 0,06
E24 steel is used in the steel load-bearing welded structures of medium-duty mining equipment. The main mechanical characteristics and chemical composition of this steel are shown in Tables III and IV.
TABLE III. Mechanical characteristics of E24 steel (according to STAS 8326-86) Material Mechanical characteristics 2 2 σr (N/mm ) σc (N/mm ) Elongation at break(%) E24 steel 350 260 21
where: σr = tensile strength , σc = flow limit
TABLE IV. Chemical characteristics (share %) of E24 steel (according to STAS 8326-86) Chemical compostion (%) Chemical compostion (%) C 0,19 Cu 0,015 Si 0,09 Ni 0,015 Mn 0,85 Cr 0,018 P 0,045 Mo 0,002 S 0,045 Nb 0,04 Al 0,022 B 0,0001 Ti 0,004 Ca 0,0001 V 0,04
The welded specimens have been achieved with a V butt welding with completion, with electrode basic type E 7018 (ISO 2560: E 51 5 B 120 20 H) for high-carbon and low alloy steels following mechanical and chemical properties (Tables V and VI).
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TABLE V. Mechanical characteristics of welding belt Welding Mecanical characteristics material Tensile Strength Flow limit σc Impact Elongation at 2 2 σr (N/mm ) (N/mm ) resistence break (%) (J) 500 - 610 420 47 24
TABEL VI. Chemical composition of welding belt Chemical C Si Mn composition Content (%) 0,07 0,5 1,0
Welding electrodes made of coated base is highly resistant to cracking both in hot and cold working.
2.3. Geometry of specimens Attempts at fatigue through plane bending were made on smooth specimens (Fig.1) welded specimens (Figure 1b) and with stress concentrator (Fig. 1c, 1d). The quality of welding belts in the case of welded specimens was verified by a nondestructive X-ray check in order to detect any discontinuities that may constitute chevrons.
a – smooth specimen b. welded specimen epruveta sudată, a V butt welding with completion
c. Stress concentrator with rounded tip d. Stress concentrator in V
Fig. 1. Geometry of specimens
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2.4. Experimental stand for tests for fatigue through bending
Experimental stand is a testing machine for fatigue through bending, flat with cantilevered specimen (Fig. 2) which allows doing tests with different degrees of asymmetry. In the paper tests were carried out in a symmetrical alternating cycle (R=-1) at a speed n=750rot/min.
Fig. 2. Machine for fatigue through flat bending
The test bench (Fig. 2) consists of: drive motor (P = 2.2kW, n = 750 rot/min), coupling, eccentric gear, leverage, device for gripping the specimen, console specimen, specimen constraint system. The fatigue tests in corrosive environment have been carried out on the same machine under test, spraying an aqueous solution of 3.5% NaCl and 6% H2SO4 on the samples.
3. EXPERIMENTAL RESULTS THAT WERE USED From measurements made on smooth steel specimens brand E36, respectively E24 in corrosive environment, respectively in the air, curves of sustainability were traced in log coordinates σ - log N (Fig. 3 a, b). It was found that the smooth specimens show greater durability in the air than in corrosive environment. Simultaneous operation of a further mechanical stress with a chemical factor lead to a deterioration quicker than it would have been if the specimen had been subjected separately to a cyclical effort in the air or a simple corrosive action [3]. Under the influence of variable loads of protective oxide films, breaking leads to local anodic dissolutions of metal and to pitting corrosion. Corrosion pinching can be considered stress concentrators and are chevrons for fatigue cracks. As a result of stress concentration also occurs an intensification of local deformations that may be higher than those considered by the nominal value of tensions. Additionally, due to local strains of inelastic nature, the mode of action of the load may differ from that considered under the action of nominal tensions [1].
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b a Fig. 3. Fatigue durability in corrosive environment, respectively in the air for smooth specimens made of E36 (a), respectively E24 (b) steel brand.
In Fig. 4 are shown the curves of durability in corrosive environment of welded specimens made of the two brands of steel E36 and E24. It is noted that both types of steel have similar behavior. It can be considered that this type of behavior occurs due to the similarity of the chemical compositions and the mechanical resistance characteristics. Attempts of fatigue in corrosive environment showed that specimens with stress concentrator in V have a durability 82% lower than the stress concentrator with a rounded tip. Meanwhile, tension concentrator specimens with smooth rounded tip have a durability approximately 68% lower than the smooth specimens without tension concentrator (Fig. 5).
Fig. 5. Durabily at fatigue in corrosive Fig. 4. Durabily at fatigue in corrosive environment for specimens without tension environment for welded concentrator, with tension specimens made from E36 and E24 steels concentrator with a rounded tip and with a tension concentrator in V
4. CONCLUSIONS ON THE EVALUATION OF DURABILITY TO FATIGUE Comparative evaluation of the durability of smooth steel specimens made of naval steel E36 brand tested in corrosive environment highlights the fact that in the corrosive environment (3.5% NaCl solution and 6% H2SO4) this feature is 52% less than that in air. Attempts of fatigue in corrosive environment have shown that welded specimens have less durability by about 42% than non-welded ones.
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The welding process influences fatigue endurance limit, as a result of the change of the mechanical properties and the structure of the metal in the ZIT. Fatigue resistance in corrosive environment is influenced by the shape and sharpness of tension concentrator but also the level of the load that has been applied.
REFERENCES [1] L. Palaghian, I.G. Bîrsan, Solicitări mecanice ale oţelurilor în medii corosive, EdituraTehnică,Bucureşti, 1999, ISBN 973-31-1402-2. [2] S. Băicean - Studii privind degradarea prin oboseală în mediu coroziv a unor oţeluri navale, Teza de doctorat, Galaţi, 2010 [3] C.F.Ciofu - Studies on ensuring a longer operation lifetime of the component parts of the heat exchangers - International Conference on Energy and Environment Technologies and Equipment (EEETE 14), Advances in Enviromental Technology and Biotechnology, Braşov, Romania, June 26-28, 2014 – Energy, Environmental and Structural Engineering Series,nr.26, pag.43.
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RESEARCH ON DEGRADATION CORROSIVE ENVIRONMENT OF SOME STEELS USED IN MANUFACTURING MINING EQUIPMENT. MICROSCOPIC ANALYSIS
Lecturer PhD. eng. Florin CIOFU, Engineering Faculty, ‖Constantin Brâncuşi‖ University, [email protected] Lecturer PhD. eng. Alin NIOAŢĂ, Engineering Faculty, ‖Constantin Brâncuşi‖ University, [email protected]
Abstract: By those shown in both the previous study and those presented in this paper we intend to deal with an unfavorable aspect, frequently found in surface mining workings of the coal basin of Oltenia. The excavating machines of these coal pits are subjected to difficult working conditions: dust (fine mineral particles with sizes up to 10μm or even less), temperature differences (in summer up to+50oC and in winter to-30oC), corrosive atmosphere (acid underground waters, sulfates, gases resulting from the extraction of coal - like SOx generated from calcination sulfides, nitrates), etc ... In terms of mobility, these machines are designed in such a way to adapt both to relief conditions (moving horizontally or in an inclined plane) and to larger or restricted spaces of maneuverability. Also they can move to different working fronts using the march mechanisms and the arms (of excavation ,respectively of overflowing) are mobile, may rotate both horizontally around the vertical axis of the machine and vertically around some own axes [1].
Key words: metallographic, analyses, optical
1. INTRODUCTION A study carried out by the Society of Civil Engineers has determined that 80-90% of the damage occurring in steel structures are caused by the processes of fatigue, representing a process of cumulative destruction which is caused by cyclic variable loads. Metals and alloys used in the construction of the energetic equipment without being anymore in contact with different chemical environments they may interact (atmosphere air, water, steam, chemical substances), the result of this interaction being the metallic product corrosion. The simultaneous action of the mechanical and corrosive environment manifests differently on metallic materials, depending on the nature of the metal- environment type, resulting in substantial changes in their behavior to the situation in which the influence of the work environment was neglected or it was considered inert. In order to improve these defects there were analyzed and proposed remedies to prolong the life of the components of the energetic equipment. If the fatigue phenomenon occurs in the presence of an aggressive environment , this type of degradation is known as the corrosion fatigue [2]. Making statistical analyses of the incidence of this type of phenomena, it was noted that they do not follow a precise order. Some machines work according to a working schedule - repair and other equipment comes to be repaired without any schedule and with greater frequency.
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The working conditions of these machines being approximately similar, research has focused on accidental causes. The mechanical stresses which may act on the metallic material located in a corrosive environment might be stresses resulting from the application work of some external factors involved in the operating conditions or they can be residual stresses (mechanical, thermal, or structural ones) induced even during operation. The static mechanical stress (constant over time) accelerates the corrosion processes causing the material damage called the stress corrosion cracking. All static stresses occur under the action of a specific deterioration known as hydrogen embrittlement. The dynamic mechanical stress (variable over time) causes a further group of phenomena of aggravated corrosion called corrosion fatigue. Under the combination of the corrosion and corrosive wear in the fluid (liquid or gas) in a high speed turbulent flow containing solid particles may occur the erosion corrosion.
2.ANALYSES OF OPTICAL MICROSCOPY The steels studied are in the category of general use according to ISO SR CR 15608: 2002 OL 4k 37 (E24 - 4) and OL 4k 52 (E36 - 4) standard Microstructural analyses have been carried out on the basis of optical microscopy using an optical microscope of Bel Photonics MTM type. Images were made by perpendicular,, brightfield illumination ", which render bright flat surfaces. Brightfield microscopy is most used in metallography, for qualitative and quantitative analyses of the structure of metallic materials (increase over 100). Metallographic studies indicate for the analyzed material, E36 construction steel ,a ferrite-pearlite structure, in which the constituents are arranged in rows. Ferrite (F) is a homogeneous solid solution of C in Feα and perlite (P) is a structural heterogenous constituent namely a mechanical eutectic mixture consisting of ferrite (Feα - C) and cementite (Fe3C) [1]. It is known that the highest corrosion resistance is shown in the homogeneous single- phased structures. Resistance to corrosion decreases with the heterogenous structures concurrently with an increase in the degree of dispersion of the mechanical mixture. Metallographic analyses were carried out on samples subjected to varying stresses in a corrosive environment of 3.5% NaCl after different periods of time and were compared with specific aspects of control samples (unstressed samples). Thus, it has been found that the action of the corrosive environment occurs mainly on heterogeneous areas consisting of strips of pearlite, ferrite grains being less affected, resulting in changes in the continuity of the surface layer with the appearance of the first pitching on the metal surface (Fig. 1 b, c).
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a b
Fig. 1. Microstructural analysis of samples of s E36 steel; changes produced in the metalelectrolyte interface after several hours of fatigue in corrosive environment of 3.5% NaCl: a) after 5h of fatigue stress in corrosive environment; b) after 10h of stress fatigue in corrosive environment Optical microscopy studies show that after five hours of stress to the specimen, the most affected, structurally, was the surface layer of the specimen which was in direct contact with the electrolyte. The action of the corrosive environment was manifested markedly along the perlite strips, the perlite grains of the interface area corroding intensely (Fig. 1). Ferrite grains are less affected,resulting only changes of surface micro-relief,through the appearance of some uneven areas (Fig. 1b). After ten hours of fatigue stress in corrosive environment,the corrosive process is more intense, with the occurrence of corrosion products. In Fig. 2 one can notice the occurrence of some corrosion products as a result of the electrochemical reactions that occurred. It can also be noted that the electrochemical corrosion process is manifested most prominently in corrosion in the perlite belts which corrode more intenselly. Also, penetration of depth of corrosion in the steel structure has also increased.
a b
Fig. 2. Microstructural analysis of E36 steel specimens after 10h of fatigue stress
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In corrosive environment of fatigue 3.5% NaCl It has been found that during the process of fatigue in corrosive environment, the general process of crack evolution is also influenced by the mechanism of the process of corrosion under stress [3,4]. Analyzing the breaking surface of metallic materials subjected to fatigue processes in corrosive environment we can observe a partly intercrystalline relief on the entire breaking surface. Sometimes on the facets of crystalline grain limits from the fractured surface, fatigue striations are to be noted. Fractures caused by fatigue in the corrosive environment usually have several focuses of destruction, compared with fatigue in air, where this type of destruction is specific only to the surge voltage or the right of stress concentrator (Fig. 4). The evolution in time of the degradation of E36 naval steel specimens in corrosive environment of 3.5% NaCl and 6% H2SO4 at a level of 300 MPa is shown in Fig. 3b, c. It has been found that after five hours of application on the surface of the specimen corrosion pitching occur as a result of the chemical processes.
a b
c
Fig. 3. Aspects of breaking surface: a- specimen of fatigue stress in the environment (350MPa); b, c - specimen of fatigue stress in corrosive environment (300MPa)
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a
b
c
Fig.4. Cracks in sample works
3. CONCLUSION ON THE ANALYSIS OF OPTICAL MICROSCOPY The influence of the corrosive environment is mainly manifested on perlite belts of ferrite-perlite structure of E36 steel. Ferritic grains of the surface layer being is less affected, this layer will acquire an uneven microrelief, areas where pitting degradation will further develop. Microscopic studies confirm the results of profilometry research showing that the evolution of degradation from pinching to crack manifests itself by increasing their depth and not their density. 100 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
This is due to the corrosive attack on pearlite bands which leads to the increase of the depth of pinching that subsequently will become fatigue cracks. The prevalence of corrosive attack at the pearlite grain level and the occurrence of ferrite-pearlite boundaries lead to changes in the type of fatigue breaking,from intracrystalline cleavage breakage in the environment to intercrystalline breakage in corrosive environment. As demonstrated by the experimental data presented in this paper, the process of degradation through corrosion fatigue is an evolutionary process with physical, chemical and mechanical changes. The synergy of mechanical and electrochemical processes also leads to changes in the shape and structure of the surface layer. As a result of corrosion pinching that form the basis of fatigue cracks primes being considered as stress concentrators will change their geometric shape, altering the level of tension concentration. Based on these considerations, unlike variable stress in the air ,in corrosive environment the stress concentration factor has an evolutionary value over time [3,4]. Basically the effects of corrosion of a metallic material can be maintained within acceptable limits, acting in the following ways: -the appropriate selection of the metallic material; -intervening in the mechanism of corrosion; -the isolation of the metallic material from the corrosive environment.
REFERENCES [1] L. Palaghian, I.G. Bîrsan, Solicitări mecanice ale oţelurilor în medii corosive, EdituraTehnică,Bucureşti, 1999, ISBN 973-31-1402-2. [2] S. Băicean - Studii privind degradarea prin oboseală în mediu coroziv a unor oţeluri navale, Teza de doctorat, Galaţi, 2010 [3] C.F.Ciofu - Studies on ensuring a longer operation lifetime of the component parts of the heat exchangers - International Conference on Energy and Environment Technologies and Equipment (EEETE 14), Advances in Enviromental Technology and Biotechnology, Braşov, Romania, June 26-28, 2014 – Energy, Environmental and Structural Engineering Series, nr.26, pag.43. [4] Florin Ciofu, Alin Nioaţă - Experimental studies on the laser depositions of the Al2O3 powder on the plane surfaces - Annals of the University of Oradea, Fascicle of Management and Technological Engineering, IMT Oradea 2009, CNCSIS "Class B+" [5] Ciofu Florin, Nioaţă Alin –Experimental studies on the laser depositions of the powder mixtures on the plane surfaces - Scientific Conference 13th Edition, November 07-08, 2008, Tg-Jiu, Annals of the „Constantin Brâncuşi‖ no.2, page.117-122; ISSN 1844-4856, CNCSIS 718, Class C [6] A. Nioaţă - Researches regarding the optimization of thermal treatment depending on hardness for maraging 300 steel – Metalurgija, 52 (2) (april-june 2013) pp. 231-234, ISSN 0543-5846; [7] Bott T.R. - Fouling of Heat Exchangers, Elsevier Science & Technology Books, April 1995 [8] Alexandru, Ioan ş.a., The selection and use of metallic materials, Bucharest, Didactic and Pedagogic, 1997 101 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
GLASS FIBERS – MODERN METHOD IN THE WOOD BEAMS REINFORCEMENT
Lecturer Cătălina IANĂŞI, ―Constantin Brâncuşi‖ University of Tg-Jiu [email protected]
Abstract: One of the defining goals of this paper is getting new resistant material which combine the qualities of basic materials that get into its composition but not to borrow from them their negative properties. Specifically, the use of GFRP composite materials as reinforcement for wood beams under bending loads requires paying attention to several aspects of the problem such as the number of the composite layers applied on the wood beams. The results obtained in this paper indicate that the behavior of reinforced beams is totally different from that of un-reinforced one. The main conclusion of the tests is that the tensioning forces allow beam taking a maximum load for a while, something that is particularly useful when we consider a real construction, The experiments have shown that the method of increasing resistance of wood constructions with composite materials is good for it and easy to implement.
Keyword: GFRP fibers, epoxy resin, wood beams, bending test
1. INTRODUCTION In this paper is described an experimental study which was designed to evaluate the effect of GFRP on the stiffness of the wood beams [3]. By using composite materials in constructions is expected growth flexural strength and shearing, and confinement elements tablets (increased wood resistance) [5]. Applied to reinforced concrete structures for flexure, GFRP typically has a large impact on the strength of the reinforced elements. Consolidation and reinforcement is done with items as sheets and glass fiber rods [3,6]. The type of reinforcement used on the beams is the glass fiber reinforced polymer (GFRP) sheet MapeWrap G FIOCCO with a traction resistance of 2560 N/mm2 and an epoxy resin for bonding all the elements MapeWrap Primer 1. Structural epoxy resins remain the primary choice of adhesive to form the bond to fiber-reinforced plastics [5,7,8,9] and are the generally accepted adhesives in bonded GFRP–wood connections. Advantages of using epoxy resin in comparison to common wood-laminating adhesives are their gap-filling qualities and the low clamping pressures that are required. MapeWrap G FIOCCO is a special mesh made of pre-primed glass fiber, alkali resistant, which thanks to the special fabric pattern increases the ductility and uniformizes the distribution of the work on the masonry armed work. As a result, if the structure is subject to deformations, it distributes the efforts across the surface of elements that have been armed using it bag. The system adheres perfectly to the substrate so that concentrated efforts cause the support layer to yield itself before failure at the interface between the support / reinforcement system.
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2. EXPERIMENTAL STUDY The total number of wood specimens manufactured is 7, five of which are reinforced, and two are un-reinforced. The wood part of all beams was formed by dry wood beech which size is equal to 25 by 50 by 500 mm and ash which size is equal to 25 by 50 by 500 mm [3]. Three beams were reinforced using one glass fiber sheet of thickness equal to 1.5 mm, width equal to 25 mm and the length is equal to 500 cm. The finished dimension of these beams is equal to 25 by 101.5 by 500 mm because they are two beach wood beams stick together with one glass fiber sheet of MapeWrap G FIOCCO and MapeWrap Primer 1epoxy resin (fig.1) [10].
Fig. 1 Testing a reinforced wood beam with one GFRP sheets
For glass fiber sheet, once it is placed on the wood beam, with the epoxy resin, all what is required is to press the glass fiber sheet with a simple roller and pull out the air [1,2,4,6]. The GFRP are compatible with wood with respect to its mechanical properties. The bending test results for a reinforced wood beam with one GFRP sheet are shown in table 1 and the figure 2 from below:
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Fig. 2 Tension failure of a reinforced wood beam with one GFRP sheet
Table 1. Results for a reinforced wood beam with one GFRP sheet Force 100 500 800 1200 1500 1850 2050 2200 (kgf/cm2) Deflection 2 5 7 10 14 17,8 19,4 22 f (mm)
Other two beams were reinforced using two glass fiber sheets of thickness equal to 3 mm, width equal to 25 mm and the length is equal to 500 cm. The finished dimension of these beams is equal to 25 by 73 by 500 mm because they are two slides of beech up and down stick by the main ash wood beam, with two glass fiber sheets of MapeWrap G FIOCCO and MapeWrap Primer 1epoxy resin (fig.3).
Fig. 3 Testing a reinforced ash wood beam with two GFRP sheets and two slides of beech wood (up and down)
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The bending test results for a reinforced ash wood beam with two GFRP sheets and two slides of beech wood are shown in table 2.
Table 2. Results for a reinforced wood beam with two GFRP sheets Force (kgf/cm2) 20 70 150 210 270 320 390 420 Deflection f (mm) 2,2 3,6 7,5 12,7 17 22,5 28,7 35
Fig. 4 Tension failure of a reinforced ash wood beam with two GFRP sheets and two slides of beech wood (up and down) The last two beams were reinforced using one glass fiber sheet of thickness equal to 1,5 mm, width equal to 25 mm and the length is equal to 500 cm. The finished dimension of these beams is equal to 25 by 101,5 by 500 mm because they are two wood beams stick together from beach and ash with one glass fiber sheet of MapeWrap G FIOCCO and an epoxy resin MapeWrap Primer 1 (fig. 4). The bending test results are shown in table 3 [11,12].
Fig. 5 Testing a reinforced ash and beach wood beam with one GFRP sheet (in the middle of the beam)
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Table 3. Results for a reinforced wood beam with one GFRP sheet (in the middle) Force (kgf/cm2) 100 500 1100 1600 1800 2000 2100 2220 Deflection f (mm) 1 3 4 5 6 8 10 12
Fig. 6 Tension failure of a reinforced ash and beach wood beam with one GFRP sheet (in the middle of the beam)
The specimens tested were not subjected to lateral instability during loading. The total load on the beam was applied equally at one point equidistant from the reactions (the half length of the beam). We use the bending device of the universal machine for mechanical tests which has the distance between the rollers l = 460 mm. Standard samples was dry beech and ash wood beams with a rectangular section of 25x50 x500 mm (bxhxl). After we study those examples we observe that the reinforced wood beam with one GFRP sheet is the most resistant and has a good elasticity breaking at 22 mm deflection. Also, we can say that the number of composite material layers influences the stiffness of the wood reinforced beams.
CONCLUSIONS It is proposed to use an inexpensive and easily processed material that is wood. As a rigid material with good strength and relatively low cost, we use a composite. A several un-reinforced and reinforced wood beams were tested in order to find their flexural capacity. The results indicate that the behavior of reinforced beams is totally different from that of un-reinforced one. The reinforcement has changed the mode of failure from brittle to ductile and has increased the load-carrying capacity of the beams. Observations of the experimental load–displacement relationships show that flexural strength increased and middle vertical displacement decreased for wood beams reinforced with GFRP
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sheets compared to those without GFRP sheets. Also, we can say that the number of composite material layers of glass fiber sheets and their positions influence the stiffness of the wood reinforced beams.
Acknowledgments The authors is grateful to the Building Velmix Ltd, Tg-Jiu, Romania, without whose financial support the present work could hardly be conducted.
REFERENCES [1] Abdel-Magid B, Dagher HJ, and Kimball T. The effect of composite reinforcement on structural wood. In: Proceedings – ASCE 1994 materials engineering conference, Infrastructure: new materials and methods for repair, San Diego, CA, November 14–16; 1994. [2] Camille A. Issa, Ziad Kmeid. Advanced wood engineering: glulam beams. Department of Civil Engineering, Lebanese American University, Byblos, Lebanon. Construction and Building Materials 19 (2005) 99–106. [3] Ianăşi C. Research on reducing the risk of damage for the resistance elements of wooden building, 2nd WSEAS International Conference on RISK MANAGEMENT, ASSESSMENT and MITIGATION (RIMA '13) Brasov, Romania, June 1-3, 2013, pp. 161-164, ISSN 2227- 460X [4] Yeou-Fong Li, Yao-Ming Xie, Ming-Jer Tsai. Enhancement of the flexural performance of retrofitted wood beams using CFRP composite sheets. Construction and Building Materials 23 (2009) 411–422. [5] Plevris N, Triantafillou T. Creep behavior of FRP-reinforced wood members. J Struct. Eng. – ASCE 1995;121(2):174–86. [6] Plevris N, Triantafillou T. FRP-reinforced wood as structural material. J Mater Civil Eng – ASCE 1992;4(3). [7] Tingley DA, Leichti RJ. Reinforced glulam: improved wood utilization and product performance. Paper presented at Technical Forum – Globalization of wood: supply, products, and markets. Portland (Oregon): Forest Products Society; 1993. [8] Triantafillou T, Deskovic N. Innovative prestressing with FRP sheets: mechanics of short- term behavior. J Eng Mech – ASCE 1991; 117(7):1652–72. [9] Triantafillou T, Deskovic N. Prestressed FRP sheets as external reinforcement of wood members. J Struct Eng – ASCE 1992; 118(5):1270–84. [10] www.sika.ro [11] https://en.wikipedia.org/wiki/Carbon_fiber_reinforced_polymer#Civil_engineering [12] Pasăre M., Rezistenţa Materialelor, vol. 1., Editura Sitech, Craiova, ISBN 978-973-746- 621-1, 212 pg., 2007,
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CONSIDERATIONS ON THE STRUCTURE OF SINTERIZED MATERIALS FOR AUTOLUBRIFICANT HYDRODYMNIC WASTE
Cristina IONICI, Constantin Brancusi University of Tg.-Jiu, [email protected]
Abstract: Self-lubricating hydrodynamic bearings can be successfully achieved by powder metallurgy, with the great advantage that porosity can be a proper lubricant tank. By self-lubricating material or sintered anti- friction material is meant a material that has to meet complex requirements of mechanical, thermal, chemical and economic nature. Then one can study this phenomenon, Reynolds found that due to the viscosity and the movement of one of the surfaces (inclined in the form of a) a positive pressure p developed in the part.Convergence of the lubricating film. Key words: powder metallurgy, hydraulic system, Reynolds, sintering.
1. INTRODUCTION Good mechanical properties and high economic efficiency allow the replacement of parts obtained through conventional technologies with powder metallurgy parts. The anti-friction character of a material is the cause of the many physico-chemical processes in the marginal area, moving from the surface material in motion relative to the lubricant. The structure of the surface and its properties depend on how it was made. In recent years, interest in iron-based sintered bearings has grown over the bronze, both economically and technically. Generally, iron-bearing porous bearings are used at speeds of: 1.5 m / s, for which moderate loads and 4 m / s for loads of 5 x 105 Pa. The maximum bearing load can be 60 x 105 Pa at a speed of 0.5 m / s. This type of camp, quite widespread in the hydraulic systems, because during the movement, pressure is created in the lubricant film. Then one can study this phenomenon, Reynolds found that due to the viscosity and the movement of one of the surfaces (inclined in the form of a) a positive pressure p developed in the part. The equation of determination is the equation of Reynolds is called the pressure equation.
2. EXPERIMENTAL In the case of bronze bearings, the maximum speed is 3 m / s at a load of 1.5 x 105 Pa, and the maximum load can reach 30 x 105 Pa for a speed of 0.15 m / s. For higher speeds, the bearings are provided with additional lubrication, and where thermal stresses occur, a graphite or other adhesion (MoS2). Bearings are considered to be thin-walled parts and tear-free Visible plastic, the resistance to radial crushing can be determined by testing the specimen at compression. The durability of the bearings is controlled by 2 parameters: the pressure (specific load) and the speed. By sintering, more homogeneous structures can be obtained and the properties of the materials can be improved by thermal and thermochemical treatments. Self-lubricating materials are manufactured from powders of the chemical elements that form the chemical composition of the bearing. The chemical compositions used for forming the iron matrix antifriction parts are in Table 1
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Table 1 Composition of powder mixture Composition of powder mixture Materials Iron[%] Copper[%] Tin[%] Lead[%] Molibdenum[%] Brass[%] Fe7Cu8 Rest 7 8 1 1 - Fe6Cu 5 Rest 6 5 2,5 1 - Fe5Cu5 Rest 5 5 1 1 - Fe2Cu5 Rest 2 5 1 1 2,5
Brass - is obtained from iron powder, mixed with zinc and other elements below 1%. To 70 Zn 30, powder from IMNR Bucharest. For material response to mechanical stress, the porosity of specimens obtained from powder mixtures is very important, depending on the sintering temperature and the holding time of the sintering process. We find an increase of the porosity of the samples with the increase of the sintering temperature, the maximum values being obtained at a temperature of 900 oC, while maintaining 50 minutes for the first 3 materials. For mixed blended brass, the porosity is maximal at 800 oC and 50 min hold time due to the formation of the Cu-Sn phase and its diffusion into the metal matrix, preventing the diffusion of Pb in place of the Sn, low melting granules , forming pores.
3.RESULTS AND DISCUSSION
On the properties of sintered materials of metallic powders a great influence o also represents the technological parameters of sintering: compaction pressure, temperature and duration of sintering, cooling rate. For the Fe7Cu8PbSn material sintered at 900 oC we have the structure in Figure 2.
Fig. 2. Microstructure of the Fe7Cu8PbSn sample
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The microstructure of specimens of sintered materials highlights the uniformity of the structure, the porosity, the boundaries between the particles. We present structures after sintering at 900 oC. The microstructure of the sample reveals a uniform structure and a homogeneous distribution of the phases, the basic matrix being ferrite with well-shaped grains, well-defined limits of the particles, considerable pores. Dark grains contain lead grains, which are found to be unalloyed because of solid phase insolubility. There are also small amounts of tin, iron, copper or combinations there of. For the Fe6Cu5PbSn material sintered at 900 oC we have the structures of Figure 3.
Fig.3. Microstructure of the Fe6Cu5Pb5Sn sample
Microstructures 3 highlight a structure with well-shaped grains, well-defined boundaries between particles, pores of considerable size. Dark grains contain lead grains, which are found to be unalloyed because of solid phase insolubility. The pores are generally small and rounded, but irregular pores also appear. In the structure are found the Fe-Sn, Sn- Cu and Fe-Cu phases.
For the Fe5Cu2,5Pb5Sn material sintered at 900 oC we have the structure of Figure 4.
Fig.4. Microstructure of the Fe5Cu5 sample
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The microstructure reveals a homogeneous structure and uniform distribution of the liquid phase in the well matrix base matrix. Several grains of lead, Fe-Sn, Sn-Cu and even Sn- Pb-S and Cu-Fe-S are evenly distributed in the ferrite. For Fe 2 sintered silver 5Pb material at 900 oC we have the structure in Figure 5.
Fig.5. Material with brass in microstructures
Microstructure 5 hig hlights a finer structure and a finer porosity. Homogeneous structure with well-shaped grains. The lead being insoluble is found as a separate phase. Grains of intermetallic compounds of the Fe-Sn, Sn-Cu, Sn-Pb-S and Cu-Fe-S and even of the Sn-Pb-S, Fe-Zn-S or Cu-Sn-S phase .
4. CONCLUSIONS It is found that: 1. For brass materials we have the highest porosity. 2. Cu-added alloys have maximum porosity values at different sintering temperatures. 3. As the sintering temperature increases, the porosity also increases and it varies inversely with the compaction pressure. 4. Samples with large porosities are subjected to tests for self-lubricating parts. The study and analysis of the materials determined the following: generally with the increase of the sintering temperature the porosity values increase, and with the increase of compaction pressure they are inversely proportional, therefore at low pressures we have large porosities and at high pressures we have small porosities. the brass materials in the composition have larger porosities than the other materials. structural analysis of materials shows a homogeneous structure of both constituents and porosity, the metal matrix being ferrite. The pores and pores are well-formed, the boundaries between them are well-highlighted. The most intense phases are Ferrite and Pb. Former compounds such as Cu-Sn, Fe-S, Sn-Pb-S and Cu-Fe-S, but also Sn- Pb-S, Fe-Zn-S or Cu-Sn-S are formed. This type of camp, quite widespread in the hydraulic systems, because during the movement, pressure is created in the lubricant film. 111 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
REFERENCES
[1] K.D. Christian, PhD – Thesis ,Troy (1990) . [2] T.M. Cadle –C.J. Landgraf, PM`90Wembley, Vol.2 ,124 (1990). [3] D. Dobrota, Research on the Influence of Manganese Content of Physical and Chemical Characteristics Iron-Based Sintered Products, Science of Sintering, Vol.45, No.1, I pp. 21- 29, (2013). [4] Fa. Schenck : Information leaflet , Rotating beam machine “Rapid Pum” [5] D. Spoljaric- H. Danninger –B. Weiss- R. Stickler : Proc . PM Auto `96 , Isfahan-Iran , (1996).
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PARAMETERS AND FACTORS OF PROCESSING THROUGH COMPLEX EROSION Lecturer PhD. eng. Alin NIOAŢĂ, Engineering Faculty, ‖Constantin Brâncuşi‖ University, [email protected] Lecturer PhD. eng. Florin CIOFU, Engineering Faculty, ‖Constantin Brâncuşi‖ University, [email protected]
ABSTRACT: The process of processing through complex erosion is influenced by a large number of parameters and factors, acting in close interdependence and influencing each other in order to achieve the stability of the process of processing and the achievement of the final technological characteristics. The dimensions characterizing the process of processing, imposed on it and having constant values, are process parameters. The dimensions that contribute to the development of the fundamental phenomena of the mechanism of processing through complex erosion and contribute to the definition of the technological characteristics are factors. Keywords: complex erosion, tension voltage, current density, contact pressure
The characteristics of the parameters and factors determine the proportion of participation in the material sampling of one of the specific elementary processes, determining the overall erosive effect and ultimately the processing characteristics. The parameters and factors presented in Figure 1 are considered to be representative for the dimensional processing through complex electrical erosion. The parameters characteristic to the method are of different nature, namely: electrical - defined by the intensity of the electric current, respectively the current density and the process voltage; mechanical - represented by the peripheral speed of the electrode- tool and the depth of machining and advancement in some studies, or in others, merging the latter two parameters, from the point of view of the pressing force between the electrode and the semi- product, namely the pressure force; hydrodynamical - represented by the working environment.
Fig. 1 Parameters and factors of processing through complex electrical erosion
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The parameters influence the weight of elementary processes, and the factors determine the development of these processes. The tension voltage on the working space is a parameter on the size of which depends the stability of the processing process. In the low voltage range (8 ... 12 V), the amount of released energy is reduced (about 2 ... 5% of the arc discharge energy) and is due to the Joule- Lenz heating effect. In the field of medium voltage (12 ... 22 V), breaking of the contacts will cause the non- stationary arc to appear with pronounced thermal effects. It is appreciated that in this field the balance of the elementary processes is achieved, which ensures the stability of the process, the development of the energy of effect and the evacuation of the erosive products. This area is considered to be the optimal one and leads to a processed surface with the lowest value of roughness and depth of the modified layer, at minimum energy consumption. In the field of high voltages (22 ... 32 V), the percentage of non-stationary arc discharges accompanied by pronounced thermal effects is high. The temperature of the bonding bridges is close to or exceeds the melting temperature so that the material melts and sometimes even vaporises explosively. Dependence of voltage productivity is shown in Figure 2.
Fig. 2 Dependence of processing productivityon working tension voltage
The electric current is the determinant parameter of the process, being a relative size that depends on the size of the active surface that is involved in the process. Thus, the specific I size j , current density, is considered to be the main parameter of the process. S At low current densities (j <20 A/mm2), if working voltage is low, processing takes place on the basis of the electrochemical process. Higher processing qualities, high dimensional precision, pronounced shrinkage of the modified layer and heat-affected area (ZIT) are obtained, and almost total removal of the microfissures will occur, with productivity 114 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
reduction in return. At high current densities (j> 20 A/mm2) and corresponding voltages, the processing is predominantly achieved due to impulse electrical discharges generated at the level of the microasperities peaks, the weight of the erosive process being determined by the effects of the thermal process. In this case the productivity increases, producing negative effects on the quality of the processed surface , on the dimensional precision, on the ZIT thermal influence zone, and on the modified layer. With an excessive increase in current density, either in the presence of low or high tension voltages, the erosion process degenerates causing a short circuit to occur at low voltages or static arc electrical discharge. The dependence between current density and productivity is shown in Figure 3.
Fig. 3 Dependence between current density and the productivity of the processing
The contact pressure p = 1 ... 10 Mpa, on the value of which other parameters depend, especially the current density, is another important factor. The optimal pressure value limits the number of contact bridges between the transfer object and the object to be processed and the size of their section, the passive film having an important role in preventing the transfer object from and the object to be processed being short-circuited. If the pressure rises above a certain limit, there is no balance between the amount of formed and removed film, thereby increasing the contact surface between electrodes tending to short-circuit. Figure 4 shows the influence of pressure on productivity
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Fig. 4 Dependence of processing productivity on working pressure
Feed speed vs = 1 ... 100 mm/s. At low feed speeds, the absorbed power (transmitted to the processing area) is only 2/10 ... 3/10 of the maximum power of the transformer because there is a change in working mode with an idle running one and the spring is unstable and is often interrupted. The size of the feed leads to an increase in the number of discharges and the density of the current, thus increasing the absorbed power, which creates favorable conditions for the spontaneous vaporization and spraying of the whole molten metal out of the working space, but leads to a deterioration of the processed surface and a reduction of the pecific energy consumption. Processing depth t = 0.1 ... 5 mm. The influence of the processing depth on the absorbed power and thus of the specific energy consumption is similar to that of the feed rate. The size of the processing depth and of the feed rate determines the surface on which the material is sampled; they must be chosen in such a way that the perimeter of the surface on which the material is to be sampled should be minimal; the choice of the feed rate depends on the depth of processing. Peripheral velocity of the electrode ve = 10 ... 50 m/s; It is advisable to rotate the electrode in the opposite direction to the semi-product. The speed ensures the balance of the elementary processes, determines and limits the energy of effect in the elementary space, having a decisive role both in determining the contact duration and in printing the discharging character in the non-stationary arc. The low speeds determine the increase of the existence duration of the microcontacts and consequently there is a strong increase in the electric power introduced by the Joule-Lenz effect, but much of it is lost by dissipating in the body mass in contact without being useful for the erosion process. At such speeds, the material sampling is due in particular to the long arc - from the cathode to the anode, and the total anode erosion is reduced.The quality of the surface and productivity are inadequate. At high speeds, productivity increases, roughness decreases and structural changes in the superficial layer are reduced. Due to the action of the working environment (especially
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water), the metallic contacts decrease as the speed increases, so that if the speed is too high, the contacts may no longer appear. The working environment: soluble glass solutions, compressed air, kaolin aqueous solutions, technological water with added sodium and potassium salts, technological water. Presently, on technical and economic considerations,the industrial practice has mostly validated compressed air and technological water as working environments. There are three main directions of action of the working environment, namely: activation of the erosive phenomenon, localization of effect energy and activation of the evacuation process. The working environment must be maintained at optimal processing temperatures. Research has shown that space heating above 40C leads to substantial changes in the conditions of the process. The cooling the action area of the electric arc and the rapid movement of the electrode lead to the destabilization of the arc and the reduction of the length of the arc. Pair of electrode material–semi-product: The electrode can be made of graphite, steel, brass, aluminum, cast iron, copper, and the semi-product must be an electrically conductive material with a lower melting temperature than that of the arc. The method is economically efficient for the processing of heat-resistant materials and high ohmic resistance, namely metals and alloys with high hardness and toughness: alloyed steels, austenitic and martensitic stainless , refractory alloys, etc. The pair of electrode material - semi-finished material is an important factor in the characterization of the processing ability of the materials, constituting the direction of generalizing the complex electrical erosion processing. The pair of electrode - semifinished material can direct and optimize the processing characteristics, their thermophysical properties, giving them a different processing behavior: for example, the roughness of processed surfaces resulting from sintered carbide is lower and the productivity slightly higher than that obtained in the same conditions for the processing of fast steel; using a copper electrode leads to a lesser relative wear (less than 20%) than when using an OLC 45 steel (over 40%); also, the productivity on processing with a soft steel is slightly lower than in the case of using a copper electrode. Structure of electrical circuit of power supply: • welding transformers / converters; • special transformers. It influences the amount of heat introduced into the process: the idea is to transmit to the electrode-semi-finished surface a large amount of energy in a very short time so that to produce a strong heating of the contact microwells without affecting the mass of the semi- product in depth. These conditions are provided by the inductive structures and relatively rigid characteristics of the power supply. The magnetic field: • internally – having a role in evacuating the erosive products and ensuring the stability of the process; • externally - perpendicular to the axis of the discharge channel and parallel to the axis of the semi-product.It reduces energy consumption, wear of the electrode and the possibility of melting drops of molten metal on the surface of the semi-product.
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Automatic adjustment of the workspace: • determines the stability of processing with high weight and is an effective way of conducting and optimizing the process; correlates electrical and mechanical parameters for objectively observing a function during processing: maximum productivity, minimum specific consumption of electrical energy, roughness of the processed surfaces and minimum ZIT heat-affected zone ; even in the case of a partial correlation of parameters, the automatic adjustment of the elementary workspace has very important repercussions in the processing itself and the achievement of the desired technological characteristics.
Conclusions The factors that influence the processing through the EREC act in close interdependence and influence each other. They can be grouped into determinant factors of influence for other factors and factors of influence determined in turn by others. This complexity of factors and their mutual influences demonstrate the complexity of the EREC process and is an explanation for the complexity of the models required for the theoretical analysis of the processing. In conclusion, due to the special character of the processing through the EREC , the fundamental phenomena developed in SL depend on a whole range of parameters and factors, while acting in a dynamic interdependence at the same time. Depending on the variation of these parameters and factors, they are also influenced by the results of the processing, namely: • global erosive effect; • weight of elementary processes; • stability of the processing process; • global technological features.
Bibliography [1] Gavrilaş, I. ş.a. - Prelucrări neconvenţionale în construcţia de maşini -Editura Tehnică, Bucureşti, 1991. [2] Herman, R.I.E., ş.a. – Prelucrarea prin eroziune complexă electrică- electrochimică, Editura Augusta, Timişoara, 2004. [3] Nagîţ, Gh., - Tehnologii neconvenţionale, Universitatea Tehnică „Gh. Asachi‖, Iaşi, 1998. [4] Nanu, A., - Tehnologia materialelor, Editura Didactică și Pedagogică, București, 1983. [5] Nichici, Al., ș.a. - Prelucrarea prin eroziune în construcția de mașini, Editura Facla, Timișoara, 1983. [6] Nioaţă, A., – Cercetări teoretice şi experimentale privind optimizarea unor parametri ai prelucrării prin eroziune complexă, Teză de doctorat, Sibiu, iulie 2007. [7] Popa, M., ș.a. – Utilizarea inteligenței artificiale în conducerea procesului tehnologic de eroziune electrică, Editura Augusta, Timișoara, 1998.
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PROCESSING OPERATIONS OF METALLIC CARBIDES THROUGH COMPLEX EROSION
Lecturer PhD. eng. Alin NIOAŢĂ, Engineering Faculty, ‖Constantin Brâncuşi‖ University, [email protected] Lecturer PhD. eng. Florin CIOFU, Engineering Faculty, ‖Constantin Brâncuşi‖ University, [email protected]
ABSTRACT: With the diversification of the types of materials, due to the requirements of high strength and hardness and, at the same time, with the necessity of increasing their processing speed, it was necessary to conceive and realize new processing technologies, which ensure obtaining of parts with mechanical properties with a complex form, multi-faceted surfaces and the use of appropriate tools for them.
Keywords:: complex erosion, metallic carbides, rectification, profiled discs
1. Yielding /Cutting operations The yielding of hard-to-process metal materials is at present the area where the complex erosion process is very effective. Cuts with minimal material losses and low energy consumption can be achieved. The pieces can be up to 500 mm in diameter or side, and the amount of sampled material can reach values over 10000 mm3/min. Cutting can be done with different electrodes (OT): tape, wire, disc.The most common are disk electrodes considering their robustness in operation and the main-constructive simplicity of the machines. Table 1 shows the characteristics of the deburring discs, and in Table 2 the usual regimes for complex erosion yielding.
Table 1:Characteristics of of the deburring discs for cutting through complex erosion Dimensions of Dimensions of the discdiscului Diameter the semi- Material of grip- Diameter Thickness Diameter of product [mm] flanges D D [mm] g [mm] borehole d [mm] f [mm] Up to 30 300 0,5 15...20 STAS 40...50 30...100 200...400 0,8...1 25...30 500/2-80 50...80 100...200 400...700 1,0...1,5 30...35 general 100...150 200...400 700...1200 1,5...2,0 35...45 purpose 150...200 carbon steel
Table 2: Working regimes for cutting through complex erosion Diameter of the Working Current Pressure between Electrolyte semi-product ds tension U intensity I electrodes p Cutting Q [mm] [V] [A] [daN/cm2] [m3/h] 10...20 20...22 20...40 0,5...1,0 0,5 20...40 20...22 40...80 0,5...1,0 0,5 40...80 20...22 80...125 0,5...1,0 0,5 119 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
80...125 22...24 125...200 1,5...2,0 1,0 125...150 24...26 200...275 1,5...2,0 1,0 150...200 24...26 275...350 1,5...2,5 2,0 200...250 26...28 350...450 2,0...3,0 2,0 250...400 28...30 450...600 2,0...3,0 2,5...3,0
A particular problem is the metallic carbides. Their behavior in complex erosion processing is determined by their physical and mechanical properties, properties which are dependent on binder content (Co) and in carbides such as TiC, TaC, CW (Table 3). Under the action of thermal and mechanical stress they can crack and for this reason there are certain processing restrictions, materialized by a differentiation of regimes according to the type of carbide and depending on the chemical composition. The cobalt content, which gives the carbide an increase in energy storage capacity of deforming without cracking, can be an indicator to be taken into account when choosing the processing regimes and when establishing a suitable impedance of the circuit (usually inductive).
Table 3: General physical-chemical properties of the metallic carbides Material K 10 K 20 K 30 K 60 P 40 P 10 CW Co Composition [%] CW 94 85 77 75 74 64 100 — Composition [%] Co 6 12 20 25 14 9 — 100 Composition [%] TiC+TaC — 3 3 — 12 27 — — Tensile strength by bending 170 210 260 280 190 130 40 195 [daN/mm2] Coefficient of volumetric 15 16.5 17.9 20 17.5 21 21,6 15,3 expansion γ [1/K] 10-6 10-6 10-6 10-6 10-6 10-6 10-6 10-6 Thermal conductivity 80 62 28,5 23,9 22 21 122 71 λ [W/mK] Mass calorical capacity C 151 220 265 214 — 336 — 442 [J/kgK] Specific mass ρ [g/cm3] 14,8 14,3 13,7 12,8 12,6 10,7 15,7 8,7 Thermal diffuseness α 0,129 — — — — 0,0254 — 0,0666 [m2/h] Melting temperature [K] — 2870 — — — — 3640 1760
Metallic carbides have low resiliency, their resistance to thermal or mechanical shocks being very low. The cumulative action of the mechanical and thermal effects inherent in the complex erosion processing, rapid heating and cooling can stress the material well beyond the tolerable bending strength, compression. As a result, there are phenomena of plastic deformation, dilations and sudden contractions, resulting in slides of layers, local ruptures, cracks, the intensity of which depending on the structure and, respectively, composition of the 120 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
carbide sort. The intensification of the working regime (U, I) leads to the intensification of these phenomena, with undesirable consequences for the technological indicators such as precision productivity, surface roughness etc. It is important, from this point of view, to set some restrictions in the programming of the energy parameters of the impulses according to the chemical composition (structure), in order to obtain a certain technological indicator. Table 4 reproduces indicative data obtained from the normal processing of some sorts of carbides.
Table 4: Working regimes for cutting metallic carbides through complex erosion Carbide Dimensions Disc Working Working Productivity- Electrolyte 3 sort [mm] diameter D tension U [V] current I [V] Qp [mm /min] [mm] P 01 30x20x10 160 18...22 20...30 45...50 P 10 30x20x10 160 18...22 20...30 50...55 Soluble P 40 32x18x10 160 18...22 20...30 50...60 sodium K 15 25x15x10 160 18...22 20...30 50...57 silicate K 30 60 160 18...22 30...40 62...65
2. Rectification through complex erosion Sharpening of metallic carbide-plated tools or made of high-quality steels like fast steels, extra alloys, etc. requires a high consumption of diamond abrasive discs, which increase the cost of the operation. Replacing the mechanical sharpening with complex erosion sharpening has a series of economic and technological advantages: low power consumption, machine constructive simplicity, very cheap electrodes (OT), high processing precision, etc. Table 5 presents comparative data between mechanical rectification and complex erosion for two sorts of carbides.The sharpening is made according to a diagram presented in essence in figure 1. The disc construction (OT)is shown in Figure 2. The disc is made of general purose carbon steel, rarely of cast iron or copper. In order to facilitate the access of the liquid to the processing area, there are some channels with a width and depth of 3 ... 4 mm on the front surface and inclined to the radius by 15 ... 20 °.
Table 5:Comparative data on sharpening through complex erosion and through mechanical rectification of tools Procedure of Working Productivity Electrode wear Surface sharpening regime Qp % out of the roughness Ra [mm3/min] eroded material [μm] With Roughing 35...40* 250 0,25...0,5 abrasive 25...30 discs Finishing 50...60 200 0,2...0,3 40...45 With 7,0...8,8 2,0...3,0 0,2...0,3 abrasive Finishing 5,0...6,0 paste 121 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
Roughing 120...150 15...25 3,0...3,5 Through 150...200 complex Semifinisare 25...30 5,0...10 1,0...2,0 erosion Semi-finishing 40...45 Finishing 1,0...2,0 2,0...4,0 0,25...0,3 2,0...3,0 * The values from the numerator are for P 10 carbides and from the denominator for K 40 carbides
Fig.1 Diagram for sharpening the tools through rectification: OT-Object of transfer; OP-Object to be processed; AE- Electrolyte feed; C-collector; R-rheostat; A-ammeter; V-voltmeter.
Fig.2 Construction of the rectifying disc: IC- grooved ring ; C-channel; SF-fastening screw; F-flange; B-hub 122 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
The regimes of processing and surface roughness on the rectification of the metal carbide blades are given in Table 6.
Table 6: Processing regimes and surface roughness for rectification through complex erosion of metallic carbides Peripheral speed of the electrode [m/s] 10 30 P 10 K40 P 10 K 40 0 1 2 3 4 5 Current I [A] 35-40 40-50 35-40 60-65 Roughing Tension U [V] 18-20 18-20 20-22 20-22 Processing productivity Qp [mm3/min] 90-100 80-85 70-80 90-95 Microfissures depth h 0,3 0,25 0,16-0,17 0,13-0,14 [mm] Roughness of surfaces 2,5...12,5 25-12,5 25-12,5 25-12,5 Ra [μm] Working surface 100 100 100 100 2 Al mm Currentul I [A] 8-10 10-12 8-10 20-22 Tension U [V] 10-12 10-12 15-16 15-16 Processing productivity Qp Semifinishing [mm3/min] 40-50 30-40 30-35 30-40 Microfissures depth h 0,16-0,17 0,08- 0,06-0,07 0,05-0,06 [mm] 0,10 Roughness of surfaces 12,5-6,3 12,5-6,3 12,5-6,3 12,5-6,3 Ra [μm] Working surface 100 100 100 100 2 Al mm Current I [A] 3-4 3-4 3-4 3-4 Tension U [V] 6-8 5-6 8-10 8-10 Processing productivity Qp [mm3/min] 5-8 3-5 3-5 5-7 Finishing Microfissures depth h 0,08-0,01 0,08- 0,03-0,05 0,03-0,05 [mm] 0,01 Roughness of surfaces 0,4-0,5 0,4-0,5 0,4-0,5 0,4-0,5 Ra [μm] Working surface 100 100 100 100 2 Al mm
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3. Profiling through complex erosion Profiling is performed with shaped electrodes similar to sharpening discs, but with the active peripheral surface correspondingly profiled (Figure 3).
Fig. 3 Profiled discs A - angular (sharp) profile; B - rectangular profile; C - circular profile
The working modes, similar to rectification, are chosen according to the electrode material and are of roughing, semi-finishing and finishing. Profiling through complex erosion is done under much more efficient conditions than by classical mechanical methods, reducing the consumption of abrasive tools and critical diamonds. Still a profiling operation is the calibration of the rolling mill cylinders. The principle of this operation is shown in Figure 4.
Fig. 4 Diagram of rolling mill cylinders calibration through complex erosion
Initially it penetrates to the required depth, the electrode (OT) rotating at a peripheral speed of 20-25 m/s, performing a corresponding transverse advance. At this stage the OP stays in place. In the next phase, of proper profiling, the transverse advance stops, the electrode performing only the rotation. The circular working advance , S, is automatically executed by the OP with the speed imposed by the process, respectively by the automation system. After crossing the circumference of the cylinder, it still performs rotations for correcting the shape
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and size of the profile as a result of OT wear. In the ZL working area, the fluid is brought through the SAE electrolyte feed system. The working regimes are similar to those of rectification-profiling.
4. Conclusions The limitations of the classical processing methods are derived from the conditions imposed by the mode of transmission of the processing energy through the mechanical contact between the object to be processed and the transfer object: the need for the transfer object to be tougher than the object to be processed; the rigidity of the transfer object and the object to be processed should be appropriate to the mechanical forces occurring during processing; the object to be processed should not exhibit exclusively brittle fracture; the transfer object can pass the surface of the transfer object gradually, in successive strips and layers, if the operation is a cutting operation, etc. Unconventional processes are applicable where traditional methods become economically unsatisfactory or even impossible to apply: for processing parts of materials with exceptional properties (hardness, brittleness, corrosion resistance, etc.); for processing with working parameters which are just on the line: very low speeds, very low or very high temperatures, very low or very high pressures and powers; very small or very large machining; processing requiring very strict precision and roughness; processing surfaces with complex configurations, difficult or impossible to obtain in any other way.
Bibliography [1] Gavrilaş, I. ş.a. - Prelucrări neconvenţionale în construcţia de maşini -Editura Tehnică, Bucureşti, 1991. [2] Herman, R.I.E., ş.a. – Prelucrarea prin eroziune complexă electrică- electrochimică, Editura Augusta, Timişoara, 2004. [3] Nagîţ, Gh., - Tehnologii neconvenţionale, Universitatea Tehnică „Gh. Asachi‖, Iaşi, 1998. [4] Nanu, A., - Tehnologia materialelor, Editura Didactică și Pedagogică, București, 1983. [5] Nichici, Al., ș.a. - Prelucrarea prin eroziune în construcția de mașini, Editura Facla, Timișoara, 1983. [6] Nioaţă, A., – Cercetări teoretice şi experimentale privind optimizarea unor parametri ai prelucrării prin eroziune complexă, Teză de doctorat, Sibiu, iulie 2007. [7] Popa, M., ș.a. – Utilizarea inteligenței artificiale în conducerea procesului tehnologic de eroziune electrică, Editura Augusta, Timișoara, 1998.
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A SHORT ANALYSIS OF THE OF THE SMARTPHONES RELIABILITY
Dr.ing. Adrian Stere PARIS, Univ. Politehnica Bucharest, email: [email protected]
Abstract A short analysis of some new results in the area of the reliability for smart mobile phones, the most used electronic devices, is of personal interest for every modern person. The strong competition induced by the globalization imposed necessary developments of the quality and reliability, fixed by ISO 9001-2015. The necessary huge availability of the mobile devices renders necessary new hardware and software efforts for reliability, especially for the first two competitors, Android and iOS. The paper presents mainly a short overview of a few recent statistical results, especially for the failure rates, and a comparison with older values (2011). An important growth of the reliability and availability is easy to detect, associated with the big efforts of the producers in testing these devices and huge development of applications.
Key words: reliability, smartphones, software
1. Introduction The mobile phones, the most used electronic devices in the present, have a great impact on communications and business, making more accessible and rapid manipulation of data. An up-to-date study of the market share of global smartphone Operating Systems shipments by mobile operating system per quarter from STATISTA [7] shows the big predominance of Android, an open source operating system released by the mighty Google. In all the quarters of the year 2016 (fig.1) [7] it is obvious the majority of Android apps(around 80%), the existence of iOS (around 17%)and a few Windows (rest) or other OS. Table 1 presents the comparative evolution of smatphones sales in 2016 and 2015, with practically the same results [8]. This usage level shows even a degree of reliability of smartphone OS. One of the greatest features of the Android OS is the wide range of apps applications found in its marketplace, now known as the Google Play Store: with the open source philosophy (which is amazing) almost anyone had the opportunity to create an app for the Android Play Store.
Operating 4Q16 Units 4Q16 4Q15 Units 4Q15 System [thousands] Market [thousands] Market Share[%] Share[%] Android 352670 81.7 3253944 80.7 iOS 77039 17.9 71.526 17.7 Windows 1092 0.3 4395 1.1 BlackBerry 208 0.0 907 0.25 Other OS 530 0.1 887 0.25 Total 431539 100 403109 100
Tab. 1 The comparative evolution of smatphones sales Fig.1 Market sharee 2016 [7] in 2016 and 2015 [8]
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2. Smartphone reliability problems The strong impact of the smartphones reliability was pointed out in the last time with the model Samsung Galaxy Note 7, with "a manufacturing defect in the corner of the batteries. A design flaw made the electrodes prone to bending. This could lead to a separation and short-circuit in the battery itself, and was responsible for some of the fires" [2]. A welding defect and a lack of insulation tape could lead to problems with the batteries [2].
Fig. 2 Samsung Galaxy Note 7model reliability problems[2]
Except for this case, the lack or poorness of published smartphone failure data for secrecy reasons renders difficult any evaluation of their reliability. An early study (2010) of SquareTrade [11] compared the failure rates of iPhone, Blackberry, and the 2 major Android phone manufacturers (Motorola and HTC), as well as an aggregated pool of all other smart phones. The customer reported failure data were analyzed from a sample of over 50,000 new mobile phones (Fig.3)[11]. Additionally Square Trade compared the malfunction rates for different data processing digital devices (Fig.4) [11].
Fig.3 Reported malfunction rate after Fig.4 Reported malfunction rate after 12 months of smartphone use 12 months of smartphone use
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The smartphone's important reliability achievements in the reliability is obvious (fig.4): they are the newest devices in the data processing category (2010!) and these phones are among the most reliable electronic products.
3. Some evaluations on smartphones reliability An overlook on the newest statistics on the smartphone reliability prove that the few published information are changing in a short time: In May 2016 Dominik Bosnjak stated in the Study „Android Smartphone Failure Rate Higher Than iOS‖ [10] , citing the research and analytics company Blancco Technology Group, that ―Android devices are significantly more unreliable than their Apple-made counterparts, with a failure rate of 44% against only 25% break down for iOS during their usage cycle‖[10]. Just after one quarter, in a new report of the same company [9],"Apple has lost its usual ‗leader‘ position to Android in the eternal smartphone performance battle. Plagued by crashing apps, WiFi connectivity and other performance issues, the iOS failure rate more than doubled to 58 percent in the second quarter of 2016, compared to its 25 percent failure rate in the previous quarter" [9]. These changes should be explain by the introduction of new models, with insufficient tests, in the run for market share. On the other side the unclear definition of failure rate bounded with operator inexperience makes very difficult a consistent evaluation on reliability. The side of software and applications [4, 5] became more and more important for smartphones reliability. Software reliability, as an important quality attribute, can be defined as ―the probability of failure-free software operation for a specified period of time in a specified environment‖ [6]. The execution sequence of states and individual states determine the reliability of a software system - Software Reliability Engineering (SRE) [6]. The first software reliability growth models (SRGM) was developed in 1972 and SRGMs were initially designed to assess the evolution of software in its successive testing phases [3]. An interesting work was developed by Sonia Meskini in the master thesis ―Reliability Models Applied to Smartphone Applications‖ [2]. She investigated three popular messaging and audio- and video-calling apps (Skype, Vtok for Google and Windows app) and used mainly Weibull and Gamma distributions to model the reliability. The main registrated failure of smartphone applications had as causes: data input, hardware, wireless network, third party software, mobile data bases, OS version or software upgrades [3]. As a personal observation, it should be pointed out the big influence on the reliability of the operator attention and experience with the softwere application, that should explain the wide differences between the values of times to failures, from less than an hour to more then 1000 hours. In table 2 are given the values for the shape factor β of the Weibull reliability distributions of the analysed smartphone types.
Weibull Distribution Apps Skype V1 Skype V2 Skype V3 Vtok V1 Vtok V2 Windows β factor b = 2.82 b = 1.45 b = 1.94 b = 2.706 b = 1.79 b = 6.24 MTBF 5.49 5.71 7.74 10.02 5.18 20.46
Table 2. Reliability indicators for the analysed applications
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As it is known the Weibull distributions with β > 1 have a failure rate that increases with time, also known as wear-out failures [1]. Here all the β values are over 1 that means old products [4], what is in my opinion not very clear, considering the novelty of the applications as for example the 3 versions of Skype don't differ significantly. Further the reduced values for MTBF, in this case a few hours, except partially for Windows, confirm this remark, the wear- out of the software. The wide differences between TBF values (from 1 to 1000) render difficult an accurate interpretation of data.
4. Conclusions Any analysis of quality and reliability for smart mobile phones, the most used electronic devices, is of interest for every modern person (consumer). To avoid the possible misunderstandings it should be very useful to clearly define the threats that can affect the device and cause a drop in dependability. There are three main terms that must be clearly understood: faults (bugs), error and failure for every consistent analysis. It should be pinpointed the huge sales worldwide, and with lower prices, to consumer categories completely new, with the such advanced processing data devices. The lack of experience of those people can be considered the main source of the problems, mainly on the software side. Anyway the accelerated development of the market gives good perspectives and SRGMs will soon demonstrate this. A final choice for adequate software and hardware quality and reliability of smartphones should consider the customer conditions for experience, data volume and necessary investment.
References 1. Dodson, B., The Weibull Analysis Handbook, American Society for Quality, Quality Press, Milwaukee, 2006 2. Meskini S., Reliability Models Applied to Smartphone Applications, August 2013, Electronic Thesis and Dissertation Repository, Paper 1487, The School of Graduate and Postdoctoral Studies, The University of Western Ontario, London, Ontario, Canada 3. Meskini S., Nassif A.B., Capretz L.F., Reliability models applied to mobile applications. In Software Security and Reliability-Companion (SERE-C), 2013 IEEE 7th International Conference on, pages 155–162, June 2013. 4. Paris, A., S., Software applications for field reliability data, 4th Symposyum „DURABILITY AND RELIABILITY OF MECHANICAL SISTEMS” Univ C. Brancusi, mai 2011, Fiability and Durability, no. 1(7), Ed.Acad., Tg. Jiu, p.75-80, 2011. 5. Paris, A.S., Statistical Applications for Mobile Devices, Innovation and sustainability, 2nd International scientific conference: Sustainable innovative solutions, second edition, 28-29 October 2016, FILS, UPB, Bucharest – Romania, Ed. Niculescu 2016, ISSN 2501-6695, pp. 41-45 6. Wadhwani V., Memon F., Hameed M. M., Architecture based reliability and testing estimation for mobile applications,Wireless Networks, Information Processing and Systems, D. M. Akbar Hussain, Ed. Springer, pp. 64-75, 2009. 7. market-share-of-global-smartphone-os https://www.statista.com/statistics/236035/ market- share-of-global-smartphone-os-shipments-by-mobile-operating-system-per-quarter/
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8. Market share, http://www.theverge.com/2017/2/16/14634656/android-ios-market- share-blackberry-2016 9. Q2 2016 State of Mobile Device Performance and Health report, https://www. blancco.com/resources/rs-state-of-mobile-device-performance-and-health-trend-report-q2- 2016/ 10. Reliability reports, https://www.androidheadlines.com/ 11. Smart phone reliability: Apple iPhones with fewest failures, and major android manufacturers not far behind. SquareTrade [Online]. http://www.squaretrade.com/cell-phone- comparison-study-nov-10, 2010
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QUALITY LOSS FUNCTION FOR MACHINING PROCESS ACCURACY
Dr.ing. Adrian Stere PARIS, Univ. Politehnica Bucharest, email: [email protected] Dr. Constantin TÂRCOLEA, Univ. Politehnica Bucharest, email: [email protected]
―An article of good quality performs its intended functions without variability, and causes little loss through harmful side effects, including the cost of using it.‖ Genichi Taguchi
Abstract. The main goal of the paper is to propose new quality loss models for machining process accuracy in the classical case “zero the best”, MMF and Harris type. In addition a numerical example illustrates that the choose regression functions are directly linked with the quality loss of manufacturing process. The proposed models can be adapted for the “maximal the best” and “nominal the best” cases.
Key words: quality loss function; accuracy, MMF and Harris models
1. Introduction ―Each machining operation creates a feature which has certain geometric variations compared to its nominal geometry. One needs to estimate accuracy of various manufacturing processes in order to verify whether or not a given process plan will produce the desired design tolerances. In machining, various factors such as deformation of the workpiece and tool, vibration, thermal deformation, inaccuracies of machine tool, etc., affect the machining accuracy ―[12]. Therefore it is an important factor of manufacturing process quality, with big influences on costs and needs an association between the accuracy and costs. The Taguchi‘s methods in the engineering area were an inflexion point in the quality development in research and design. ―The quality loss function gives a financial value for customers' increasing dissatisfaction as the product performance goes below the desired target performance.‖[6] The quality quantification paradigm proposed by Taguchi is based on two fundamentals concepts: the quality loss function and the signal/noise ratio [7]. The rationale of Taguchi‘s loss function is that all the characteristics having different units of measurement and varying magnitude of scale can be converted into a single value, loss score. Another advantageous property of the loss function is that it becomes increasingly large as the value deviates from the target value [3]. There are many loss functions (cost functions) proposed and studied in the scientific papers, as models for different industrial and economical processes. The quality loss functions try to estimate the loss of the quality in financial terms [9]. Briefly speaking those functions transform quality losses in costs. A quality loss function describes a dependency between a quality index (loss of quality) and costs. The especially simple functions proposed by Taguchi, starting with the very well known quadratic model, have guaranteed a wide spreading of applications. Those models have usually little connections with the variation of the quality characteristics. Depending of type of quality characteristic there are three categories of quality loss models [7]: 131 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
the-smaller-the-better (S-type) the-larger-the-better (L-type) the-nominal-the-best (N-type.) In the case of S-type loss functions, quality losses appear due to highest-as intended outcomes. In the L-type quality losses appear due to lower -as intended outcomes [1]. In the N-type case, the target specification is fixed. Taguchi postulated the quality loss to be zero if and only if the product is on target, increasing function with growing the distance from the target, and can be different to the left or to the right of target point. For N-type loss functions Taguchi used quadratic approximation for the loss function, as model for measuring losses of society including the loss of the producer and that of the customer [1]. The success of this modeling is once mainly given by the simple mathematical formulations, easy to apply. On the other side this is a boorish fitting: a deficiency of a consistent link with the analyzed process and the unbounded values at the end of the interval.
2. Study case In view of given an example it will be used as per ISO 1708 – 1997: Reception conditions for normal lathes of general use – the precision control the P1 checking: the cutting of the cylindrical sample parts fixed in the chuck, where one of values taken into consideration is the constancy of the processed diameters, namely the difference among the diameters processed at the ends of the sample part, measured in the same axial plan [5]. The standard provides for this check a tolerance of 0.02mm for precision lathes and 0.04mm for other types of lathes (in the calculations presented here below this last higher value will be taken into account). This problem ranges in the set of lost functions zero centered, from theoretical reasons. This shows that the variable x, which is the registered deviation, has zero as its target value [5]. An example of classical Taguchi function who stats these nonmathematical conditions in analytical language, noted L(x), is: L(x)=K(x-0)2 (1) where: x is the quality characteristic; 0 - target value; K – quality loss coefficient, depending on the analyzed problem. Regression is a conceptually simple technique for investigating functional relationship between output and input decision variables of a manufacturing process and may be useful for process data description, parameter estimation, and control [2]. An important application of regression analysis is concerned with the economic aspects of the manufacturing processes [4]. The regression curves obtained from the numerical data were applied for the estimation of machining accuracy. The distribution analysis of experimental data points indicated that curve profiles can be described more adequately different of the degrees of curvature of the curves. In this paper were used the following functions:
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Harris model
For the experimental data it results: a = 114,66 b =-127,98, c = 0.03654
Fig. 1.The empirical failure function Harris for the experimental data
MMF model
For the experimental data it results: a = 0.0108; b = 0.0077; c=13.5155; d=2.2810
Fig. 2.The empirical failure function MMF for the experimental data
The different values for r (correlation coefficient) and s (experimental standard deviation): r=0.961; s=0.0856 for Harris model; r=0.991; s=0.0418 for MMF model give an clear advantage for MMF model, that should be adopted as quality loss function.
3 Conclusions In the paper following issues will be pursued: the study of the link between machining accuracy and costs; the comparative analysis of the proposed models for experimental data; the identification of most adequate stochastic law. The best results were obtained with the adaptive MMF model, since, for example, the values of the correlation coefficient are in most of the cases closed to one. Hence the modeling by truncated shifted models on a given interval represent adequate quality loss functions for ― zero the best‖ case. The studied case for machining accuracy presents a process with convex curvature, which is properly for the machine-tools with medium accuracy. The analyzed laws prove their efficiency if are applied in the design stage. To conclude, in this paper we proposed adaptive stochastic distributions for describing the loss functions in the usual manufacturing models [5]. The results that we obtained show that our approach has practical application in the design of actual strategies, allowing, moreover, for 133 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
prediction of production costs [10]. The results can be extended in the n-dimensional space, taking into consideration multidimensional variables with/without the potential interactions, which can cause a fraction of quality loss too [5], [8]. The results should be applied in the reliability area too [11].
References 1. Demetrescu M., Paris A.S., Târcolea C., Loss functions with interactions and practical application, Proceedings of the 10th WSEAS International Conference on Mathematical and Computational Methods in Science and Engineering (MACMESE'08) Bucharest, Romania, Mathematics and Computers in Science and Engineering, A Series of Reference Books and Textbooks Published by WSEAS, 2008, pp. 296-299. 2. Mukherjee I., Ray P. K., A review of optimization techniques in metal cutting processes, Computers&Industrial Engineering, 50, 2006, pp. 15-34 3. Ordoobadi S., Evaluation of advanced manufacturing technologies using Taguchi's loss functions, Journal of Manufacturing Technology Management, Vol. 20 Issue: 3, 2009, pp. 367-384. 4. Paris A. S., Târcolea C., Regression models applied to manufacturing systems In: Proceedings in Manufacturing Systems, Editura Academiei Române vol.5, nr.4, 2010, p 249- 253. 5. Paris A. S., Târcolea C., Taguchi Applications on Manufacturing Systems, International Conference on Manufacturing Systems - ICMaS 2004 08-09.10.2004 UPB, Romanian Journal of Technical Sciences Applied Mechanics, Romanian Academy Eds.Proceedings of the International Conference on Manufacturing Systems, ICMAS'2004, vol. 49, Special issue, 2004, pp.459-462, 6. Taguchi, G. Introduction to Quality Engineering, Asian Productivity Organization, 1990. 7. Taguchi, G., Elsayed E.A., Hsiang T.C., Quality Engineering in Production Systems, McGraw-Hill, 1989. 8. Târcolea C., Paris A. S., Bi-dimensional models of Taguchi type, Industrial Management 3, 1, 1995, pp. 29-32. 9. Târcolea C., Paris A. S., Loss functions used in the quality theory, U.P.B. Sci. Bull. Series A, Vol. 73, Iss. 1, 2011, pp 45-54 10.Târcolea C., Paris A. S., Sylvan, D., Loss Functions and Taguchi Theory, The 7-th International Conference of Differential Geometry and Dynamical Systems, ( DGDS- 2013), 10 - 13 October 2013, Bucharest, Romania, BSG Proceedings 21, Balkan Society of Geometers, Geometry Balkan Press, 2014, pp. 175-180. http://www.mathem.pub.ro/proc/bsgp-21/K21-ta-846.pdf 11. Târcolea C., Paris A. S., Andreescu, C. Eulerian distributions applied in the reliability, BSG PROCEEDINGS 17, (DGDS-2009) October 2009, Bucharest, Geometry Balkan Press, ISSN 1843-2654 (printed version), ISSN 1843-2859 (online version), 2010, pp. 237-242 12. Estimating Manufacturing Accuracy, https://www.isr.umd.edu/Labs/CIM/vm /ama / node19.html
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THE IMPORTANCE OF INTELLECTUAL PROPERTY PROTECTION IN TECHNOLOGICAL TRANSFER. SOME ASPECTS
Prof. dr. eng. Dan SAVESCU, Transilvania University of Brașov, [email protected]
ABSTRACT: Paper presents some aspects regarding the protection of innovative ideas. All the research results of people involved in this activity must be protected by law against counterfeiting and piracy. It should be borne in mind that there are issues of novelty and license papers / dissertation of students, not only at the level of doctoral training. So university policies on intellectual property knowledge should include acquiring of knowledge ever since the II-III study year.
Keywords: intellectual property, technologic transfer, innovation, education
Each scientific research has an element of novelty. It is necessary to awareness the importance of Intellectual Property protection of all novel parts of research, doesn‘t matter the level of researcher: student, license diploma, dissertation diploma, Ph.D., teachers, researchers, a.s.o. The policy doe in Universities must (sometimes is recommended) include courses of Intellectual Property presented by an engineer specialist, because the objects of Intellectual Property (IP) are produced by industry, are included technical aspects, appreciated only by a technician person. A lawyer is responsible for the Rights, what lies to inventor researcher applying research results, but protected by national law. Such protection is important against counterfeiting and copying, obtaining undue benefits by another person other than the inventor.
Relation between innovation and IP Innovation is the creative process (generating ideas) followed by making the changes generated by it. Products or system innovation must be protected. The State Office for Inventions and Trademarks OSIM, is the structure involved in IP protection, as central public administration, subordinated to the Government, establish the development strategy of industrial property protection in Romania and also implements the Government policy. The legal basis which entitles these above mentioned attributes is the Government Decree no 573/1998. IP has long been recognized and used by the industrialized countries and is being used by an ever increasing number of developing countries as an important tool of technological and economic development. Many developing countries are aware that IP is their biggest interest, first of all, to establish the national IP systems where they do not exist and, after, to strengthen and upgrade the existing systems which, inherited from their historical past, are no longer adequately responding to new needs and priorities. Countries have laws to protect industrial property for two main reasons, related to each other. The first one is to give statutory expression to the moral and economic rights of creators in their creations, and the other is to promote, as a deliberate act of government policy, creativity, dissemination and application of its result and, at the same time, to 135 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
encourage fair trading, thus contributing to economic and social development. The materialization of IP protection is represented by industrial property rights, IPR, which allow the creator or owner of a patent or a brand to benefit from his work or investment. The industrial property rights are outlined in Article 27 of the Universal Declaration of Human Rights, which states that everyone should enjoy the protection of moral and material interests resulted from any scientific, literary or artistic production of which is the author. IP protection is regulated by the following laws: Law no 64/1991 on patents, GO no 41/1998 on property taxes in industry and their use approved by Law no 383/2002. An efficient patent system contributes to the stimulation of innovation in three main ways [1]. First, the existence of the patent system, with the possibility of obtaining the exclusive right for an invention to work for a limited period of time, constitutes an important incentive for the inventive and innovative activity. Secondly, the limited period of time during which the patent owner is entitled to prevent others from using his invention creates an environment which facilitates the efficient development and utilization of patented inventions. It protects the inventor against uncontrolled competition from those who have not taken the initial financial risk. It thus creates conditions in which the risk capital can be safely advanced for the transformation of an invention into an innovation. The inventor will be at ease to further develop the invention into a final, commercially polished, product or process that could be marketed and produce a benefit. Thirdly, the patent system provides the framework for the collection, classification and dissemination of the richest store of technological information existing worldwide today. In other words, it contributes to the dissemination of new knowledge since the right of the inventor to prevent others from using his invention for a limited period is not freely granted. Innovation is often influenced by the environment in which innovators work. The factors that generate a favorable overall environment for inventions and innovation are: the state of science and technology; the legal, fiscal and general financial systems; the scientific and entrepreneurial culture; the technological and manufacturing infrastructure; human resources and their level of knowledge and education. The specific factors that influence innovation are represented by the relationships between universities, financial institutions, governmental offices and industry networks among others. Furthermore, the administrative and financial regulations governing the creation of new companies play an important role. At the same time, the national innovation support structures and programs for services should be viewed as a unified whole, with the main objective of increasing the capacity of society to generate inventions and innovations, including technology transfer, both at national and international level. Competitiveness is a complex concept which, at a general level, expresses the ability of persons, companies, economies, regions to maintain competition on the internal and / or especially international scale, and to get, in terms of a specific business environment, economic benefits, resulted in constant increases of productivity and standard of living. As a result, one can speak about SMEs‘ profitability.
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Research has shown that SMEs can and should contribute considerably to employment creation and trade, which ultimately promote economic growth. It has also been shown that, given the opportunity, SMEs are innovative and competitive. However, SMEs need to be encouraged to take full advantage of the existing intellectual property protection system in order to compete more successfully in the global economy.
The main stages of a process of IP management in a technological transfer organization Main stages of the Intellectual Property management can be highlighted in Figure 1. Only stages number 3 and 4 are as responsible the National Authority (OSIM); in all the others is involved only the demander [6]. 1. Establishing Intellectual Property title object
2. Registration of Intellectual Property object demand at National and Regulatory Authority
3. Obtaining the certificate of protection title after examining by the National and Regulatory Authority
4. Setting the validity of the Intellectual Property object
5. Establishment of goods and technologies applicable to Intellectual Property objects
STAGES OF 6. Setting quota in product or technology of Intellectual Property INTELLECTUAL object PROPERTY MANAGEMENT 7. Setting the period of Intellectual Property object implementation
8. Recording the techno-economic effects resulting from the application of Intellectual Property object
9. Registration achieved annual profits
10. The evidence of expenses incurred to achieve the solution protected by Intellectual Property object
11. The evidence of expenditure incurred for the implementation in production of the solution protected by Intellectual Property object
12. Record of spending to maintenance in legal terms of Intellectual Property object
13. Determination shape of the Intellectual Property object
Fig.1 – Stages of Intellectual Property management
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Stimulation and awareness IP methodology in universities Although different by their nature of activity, universities should not be seen as a self- centered system, but always take into account the labor market as a reference system compulsory to establish those landmarks necessary for self-definition in society. It should focus on the society‘s dynamic, graduates‘ development, the condition of secondary schools. Basically, the role of the university in society is to create culture. Moreover, for a contemporary approach, its role is also to provide welfare [5]. IP culture is an organizational value system resulting from an environment oriented to observing and protecting industrial / intellectual property. It consists of all the behavioral and professional reactions related to observing the right to intellectual property, reactions supported both by a law system and by a system of unwritten rules, structured over the time in institutions and society. As a result to a study performed in the most important universities, the academic environment does not consider IP culture very substantial in the Romanian universities. Some reactions are very rough and they can sometimes be conditioned by an exaggerated self- critical attitude of those interviewed. Anyway, the general conclusion is that, at this point, one cannot talk about authentic quality culture in the Romanian universities. The main coordinates of a university policy in the field should envisage the following operational systems: • A system for assuring industrial property culture (education, good practice, operative information); • An assessment system (procedures, methods, specialists); • A capitalization system (regulations, service patents); • An evaluation system (cessions, licenses, know-how). The challenge for Romania is that universities and R&D units to act as key generators of IP assets. Factors involved in this activity: teachers and researchers; doctoral students, students in their final years, students generally; sponsors; units of technology transfer (TT); intellectual property offices, regional offices / area; National Council of Small and Medium Enterprises (CNIMMC) and Businesses; Chambers of Commerce and Industry etc. Since there are sometimes contradictory interests, not very convergent, IP strategy should harmonize the interests of these factors included in universities and research institutes. IP strategy based on the interests of stakeholders assumes hereinabove: • Creating favorable conditions for the dissemination of new knowledge for the benefit of the public. • Ensuring the fair and equitable sharing of financial and other benefits of innovative product marketing, recognizing the contribution of inventors, and the institution (university, R&D unit). • Promote, encourage and support scientific research. • Attracting students to IP and capture young people's creativity. • Creating incentives for researchers and providing rewards for intellectual capital.
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IP strategy embraced by the team members must find answers to questions like: 1. Who holds the IP rights arising from research in government funding? 2. How will be distributed benefits of IP commercialization between researchers / inventors, department, institution, lender etc.)? 3. There are legal provisions for IP commercialization of research results on government funding? 4. Who holds the IP rights of private funds for research? 5. To transfer technology (T.T.) to private sector companies for marketing using "spin - off" or license agreements? 6. Who manages IP assets, including negotiation of licenses and allocation of royalties? 7. To what extent institution encourages the commercialization of research results through entrepreneurial activity? 8. What funding is assured the payment of costs for obtaining and maintaining in force the PI? 9. How does the disclosure of an invention by a researcher? 10. How are treated conflicts of interest between the duties teaching or research and commercial projects? It requires the organization of an administrative structure (office, department, etc.) or at least the appointment of a specialist to deal with the problems of protection of industrial property, an industrial property attorney attested by OSIM. The structure, reports directly to stuff (rector / senate, director technical, scientific, scientific-technical council etc.), it is good to include a lawyer (for contracts, disputes, lawsuits, etc.) and a secondary education specialist for keeping records for the various phases of implementation of inventions [6]. To achieve its purpose, the creation of the following operating systems: A system for providing industrial property culture (education, best practices, operational information); An evaluation system (procedures, methods, specialists); A system of capitalization (rules, patent department, department of IP); An evaluation system (assignments, licenses, know-how). As activities should be followed: systematization of information about the state of the IP culture in Romanian universities; successful establishment of Romanian practices in the field (universities, research institutes, technologic transfer centres etc.); study level of development of IP culture in various universities in Europe; establishing successful European practices in the field; dissemination of useful information, best practices in universities in Romania, research institutes; drawing reference material regarding national practices, successful methodologies promoted the country and its actualization at intervals, according to the new requirements, legislation, national and international political orientation etc.
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Therefore, IP culture developed in universities can be expressed by identifying and assess the following indicators: tackles subjects that PI (implicit and explicit); number of teachers specialized in IP; number of students trained annually in IP; number of teaching guidance developed in the field; number of postgraduate courses etc. Efforts in recent years in universities on promoting IP themes materialized by introducing training courses in this field at the doctoral (PhD School), possibly in the training programs of master in most cases these courses are held by lawyers. From the personal point of view and embraced by other colleagues in the country (Iasi, Cluj - Napoca, Timisoara, Bucharest etc.) these courses should be provided to the license level and having as teachers engineers (industrial property objects are engineering creations). This activity allows the development of creativity and entrepreneurship, business management through innovation since the early study years (semesters V, VI, VII).
Conclusions The concept of competitiveness should be viewed in terms of two issues: national competitiveness and competitiveness of domestic products, but taking into account market conditions, whether domestic and foreign. The national system becomes competitive when national policies are performing, with outstanding results. As it is apparent from the National Research and Development Strategy, which is supported by the European Union proposals by Horizon 2020 Program, fiscal policy measures are proposed for the development of entrepreneurship, capable of creating jobs and combating poverty. Increasing product competitiveness can be achieved by: The research results transferred to industry. Transferable technologies. Patents. Trained and accredited staff (Technology Transfer and Innovation, technology broker). Innovative SMEs. Promoting a culture of innovation and mass. Obviously, in a competitive system in which promises and are provided the necessary performance, promoting scientific research, supporting the technology transfer through simple projects, such as "Inno-voucher", to rapid fund the innovative ideas, support intellectual property through awareness and ensuring entitlements arising from technology transfer, this are secure sources of competitive products. Innovative ideas should be part of an organization's heritage, which is possible only through their legal protection. It can be considered that stimulating innovation and intellectual property protection is a prerequisite for economic growth, design, implementation of competitive products.
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In universities, R&D institutes, innovative research is a priority. Therefore the human factor in these organizations should be trained to performing design and knowledge of rights arising from the capitalization of scientific creation. An important role is education, stimulation and awareness of undergraduate, postgraduate, doctoral, researchers generally on issues of intellectual property; this is possible through courses, seminars, work-shops, inviting renowned personalities, case studies, etc.
References [1] Brad, S., Ciupan, C., Pop, L., Mocan, B., Fulea, M.: Manualul de bază al managementului de produs în ingineria şi managementul inovaţiei, Ed. Economică, Bucureşti, 2006. [2] Drucker, P. F.: Managing the Nonprofit Organization: Practice and Principles, Harper Collins, New York, 1990 [3] Gann, D., Dodson, M.: Innovation technology: How new technologies are changing? The way we innovate, National Endowment for Science, Technology and Arts, London, 2007. [4] Le Corre, A., Mischke, G.: The innovation game. A new approach to innovation management and R&D, Springer US, 2006. [5] Săvescu, D., Radu, M., Budală, A.: Elemente de proprietate intelectuală. Ghid practic. Editura LUXLIBRIS, Braşov, 2011. [6] * * * SR 13547 – 1/2/3/4. Model de dezvoltare a afacerii prin inovare. Standard Român, 2014. [7] * * * Invenţia de serviciu. Manual de bune practici. Proiect PODCA – Inovatie în administratie, 2015.
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ASPECTS ABOUT BUILDING MODELS IN INNOVATION
Prof. dr. eng. Dan SAVESCU, Transilvania University of Brașov, [email protected]
ABSTRACT: Paper presents some aspects regarding the role of the state and its policies to stimulate innovation processes, and models used in innovation.
Keywords: model, innovation, research, development, policy
The need for an active role of the state in the management of the R & D follows from the fact that science has to perform all functions in society; it cannot separate different social actors. The private sector is usually about the economic function of science, which is to stimulate technical progress and ensuring the results applied to bring commercial effect. Other functions of science (knowledge, training, prestige, etc.) are, however, equally important and must be provided by the state. These are just a few reasons that market mechanisms are unable, by themselves; provide support for research and development at a level sufficient for economic and social development. In these circumstances it is necessary to state intervention, which should provide direct support of science, and to foster the transfer of knowledge from science to economics.
Role of the state and its policies to stimulate innovation processes In a democratic decision makers allocate limited public resources, an expression of the voters' will and must take account of this fact. The general public is less aware of the importance of investing in research and development. On the other hand, the effect of investment in R & D is uncertain, and there are only a few years. Politicians are tempted rather to cut government spending for this sector and primarily distribute public money for social services, health and other areas, the expenditure reduction could cause dissatisfaction of the population or where the negative effects would be visible. This is characteristic especially where it fails justify expenditure in research and development when the national budget decreases or Pre-election years. Achieve these general objectives involved the establishment of a series of specific objectives, such as: - Increasing the scientific performance; - Development of system resources; - Strengthening the private sector; - Capacity building; - Expansion of international cooperation. The implementation of the national strategy is achieved by National RDI - PNII, GD 475/2007. To conduct the National Plan were developed a number of tools such as: - Software component; - Investment models for funding; - Monitoring procedures; - Impact assessment indicators and level of programs and plan components. 142 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
The Government Programme 2014-2020, the prospect of developing the National Strategy for RDI and the NPR - PNII were provided on the RDI system, the following: - Development and transfer of advanced technologies in the economy; - Correlation with the industrial policies of RDI activities: • Develop mechanisms for technology transfer of the results of R&D in the economy; • supporting private sector R&D activities; - Increasing the total costs for RDI; - Capacity building RDI system, both public institutions and establishments and RDI staff. In the course of industrial development have been a number of attempts to impose some order conceptual analysis of the innovation process in order to understand the nature and conduct innovation activities and to ensure a more secure the necessary innovation policy formulation. In this regard, various models have been developed innovation process by which it is possible ordering of thinking on innovation. Typically, such models of innovation have been divided into several phases or stages that relate to basic research (basic), in which there are new scientific discoveries applied research in which scientific discoveries are transformed by design-engineering in developing practical new products, processes, services, these new innovative scientific and technical achievements, from production processes are transformed into tradable goods that are running the economy. Roy Rothwell (1994) [1] gave a historical perspective of the innovation process, suggesting that the views on the nature of the innovation process evolved from a linear model (the decade from 1950 to 1960) to complex and integrated models (1980-1990). Innovation models detailing relationships and information flows between departments of industrial companies.
Models of innovation Rothwell [1] identified five generations of innovation models that reveals the stages of development of economic thought and economic realities of the community of scientists. The first generation of linear models that were prevalent in the years 1950-1960 was the model of "technology push" considering that occur on the spur technological innovation research and development: the Innovation begins with a discovery (basic research), undergoing an invention which is then harnessed by design-engineering and production activities and ends with marketing and selling innovative new product or new innovative process that are "pushed" on the market. In this approach, it is considered so that the innovation process consists of sequential phases, distinct conceptual and temporal relationships characterized by uni-directional (no feedback). Model phases of innovation "technology push" are (Figure 1):
Fundamental → Desig → Manufacturing → Marketing → Sales research nn Fig. 1. Technology Push Model
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Likelihood of success achieved innovation in "technology push" technology is the product of the probability of success and the probability of commercial success for such innovative technology [2]. The pharmaceutical industry is characterized mainly by technology-push model. A second generation of models emerged in the late 1960s and early 1970s decade, being called "market pull". These models are also linear and assume that innovation derives from a perceived market demand, which influence the direction and rate of technological development and R & D is only reactive role in the innovation process. Orientation entire innovation process takes place to meet consumer demands. Model phases for "market pull" are (Figure 2):
Market demands → R&D → Manufacturing → Sales
Fig 2. Market Pull Model
The market pull is well represented by the food industry. Both linear models were subjected to some criticism because they were very simplified representations that distort the reality of the innovation process, a process that is not linear, but is affected by feedback loops between stages underway. The third generation of models is the so-called innovation process "coupling" that can be considered as a coupling (combining) patterns "technology push" and "market pull". This model is cantered on an interactive process with emphasis on the effects of feedback between phases of market research and previous linear models. Innovation process "coupling" is logically sequential, though not necessarily continuous and interdependent phases can be divided into functionally distinct, but that interact through feedback to previous stage. The model suggests that suppliers and customers should be closely "coupled" in integrated product development teams. The fourth generation models (the 1980-90s early years) were called integrated models of innovation processes and is characterized by functional integration and product development in parallel (simultaneously) instead of sequential mode of involvement of the company's departments that are responsible for designing and developing new products. These models are based mainly on product development methods used by Japanese automotive industries and electrical products [3]. Innovative Japanese companies realize the functional integration of activities of different internal departments throughout the innovation process and also integration process development of suppliers, customers and partners. Integration within the firm takes place upstream with key suppliers and downstream clients on (applicants for the company's products). Models of the fourth generation iterations reveal complex feedback loops and reciprocal relationship between marketing, R&D, operations and distribution. Innovation process now recognizes the role that can be played by alliances with other firms and competitors. The fifth generation of models emerged in the 90s, is the integration processes and innovation systems in the network (SIN acronym). These models are based on a more general integration of systems and organizations, the formation of collaborative networks "actors"
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innovators, comprised of key suppliers, customers, other industrial companies, universities, communities etc. belonging firms. In order to take advantage of combining technology and solve problems of great complexity of new products. Innovation network includes involvement of new electronic tools, such as simulation modelling, CAD / CAM, the use of expert systems for design and manufacturing, rapid prototyping physical (Rapid Prototyping)- all leading to the so-called digitizing innovation. In networked innovation systems integrated development teams are organized in parallel addressing the creation of new products based on the concept of competitive engineering (or simultaneous) rather than based on sequential development. Research, development, design and concurrent design iterations occur. Value- creating activities of the company are intimately linked with suppliers and customers, networks and communities that include firms. The fifth generation innovation is a response to high levels of risk and uncertainty in innovation [4]. In the companies are increasing focus on the use of best practices and organizational forms, allowing maximum flexibility and sensitivity in relation to unpredictable and turbulent markets. It can be identified innovation process of the sixth generation, which is driven by enhanced opportunities to use creativity and ideas shared between different actors within and outside the company and optimization through simulation and modelling not only the creation and diffusion of new products, services and processes by which they are produced and delivered, but also the most effective strategies for providing value [4]. In the sixth generation of innovation models fall IvT approach (Innovation Technology) [4]. Based on various troubleshooting tools, such as modelling, simulation, virtual reality the extraction of data (databases) - (data mining) artificial intelligence, rapid prototyping etc.. Data extraction techniques have been used, for example, to analyse large amounts of data on customers, to identify segments of the market for new services offer very targeted. IvT approach was used in large engineering projects, such as designing the Millennium Bridge in London, the Leaning Tower of Pisa reconstruction, design, development and construction of the Guggenheim Museum Bilbao, etc. [5]. Guggenheim Museum in Bilbao was designed to support software system CATIA. In this new model of innovation, technology innovation (IvT) creates innovation, in relation to the Information and Communication Technologies (ICT) that enable innovation and manufacturing technology and operational innovation implemented. Potential benefits of these leading technologies used in innovation can be illustrated by considering the simulation techniques used in computer generated destruction tests for automotive designers. They offer significant advantages for automotive manufacturers, reducing development time and costs, avoiding the need to slow the production of prototypes for the safety tests in the early stages of the design process and expenses for their physical destruction. Some of the linear innovation models presented is more appropriate in certain contexts for certain industries. For example, the pattern "Push Technology" technology can be found in the complex (in the pharmaceutical industry) while the innovation "Market pull 'are represented more in the food industry. However, in many organizations, the innovation is more or less a mixture of the two models.
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Linear models have been compared metaphorically with a pipe because according to this theoretical construction, an increase in flows of inputs from upstream, leading to a direct increase in the number of new marketable products and processes that will influence the downstream flow. To summarize, the innovation process models have evolved from simple linear models to complex patterns of innovation in network systems integration.
IP in Transilvania University of Brasov Intellectual creation was a relevant coordinated activity in Transilvania University of Brasov. Before 2000, in University was created an Office of Inventions, which had as mission the organization, development and management portfolio of over 100 patents which, over time, have fallen by paying maintenance fees. After 2000, OSIM organized the Brasov Regional Centre for the Protection of Industrial Property, operating as a regional representative of OSIM and the European Patent Office. Since 2007, the University Senate decided to establish the Department of Intellectual Property. Intellectual Property Department - DPI - is a department with responsibilities in the area of intellectual and industrial property, being a support department for scientific research and education structure at the University Transilvania. DPI mission is to support other university structures in the process of scientific research and education through information and training the teaching staff and research students about the identification, protection and enhancement of artistic creations, scientific and technical, and protect these creations, under the law on behalf of Transilvania University. DPI objectives are: • Development, at the University level, an Organizational Culture on Intellectual Property. • Attract to the University the objects of Intellectual Property (copyright, inventions, trademarks and geographical indications and designs) and drafting legal documents establishing ownership over them. • Supporting research structures through access to information in their databases, national and international (inventions, trademarks and designs). • Stimulate and support scientific research through the identification, preservation and promotion of scientific research results as objects of intellectual property. Organizational measures reflecting a new conception of management on the importance of protecting intellectual creation in Transilvania University have increased the number of patent, utility model, some of them applied as a prototype in production. In University disciplines that tackle IP are included in the thematic of the Doctoral School, and since 2011 have been introduced in the curricula at the undergraduate departments Waste Management Engineering, Engineering and Environmental Protection, Energy Renewable Systems Engineering and Industrial Design, these courses are presented by the undersigned as well as applications seminar / project. At the same time it opened a second point of information - documentation in Technology and Business Incubator space of the university, ITA Pro-Energ. They were drafted documentation, books, and courses of intellectual property.
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In ITA Pro-Energ Incubator [6] are ongoing consulting activities on intellectual property and was organized a documentation/reading room. Are worth supporting activities in trade mark for a few companies (a fairly consistent list) and not at least, advice to students who have innovative ideas for products, to be protected by Patent Demand or Utility Model. However experience has made me to be asked to participate in developing a Best Practice Guide for Law 83/2014 (service invention), the working group WG1 completed in 2015 [7].
Conclusions It is difficult to establish a universal recipe, influencing innovation and evolution over time. Throughout history were developed ideas were generated scenarios were created models to guide in a positive way the innovative development of market economy based on innovative performance. Innovation models developed have contributed, each in their time and awareness of the need to stimulate economic development through innovation. It may be that there are still many unused resources, such as the creation and entrepreneurship in universities, research centres and development among young researchers. A good practice is found in the efforts of the European Union, the World Intellectual Property Organization (WIPO) to introduce the knowledge of intellectual property in universities, the teaching of this subject at undergraduate level in deepening their final years and the master's and doctoral awareness that any further research made has a value that must be protected. It were established, during the meeting in The Hague in 2009 and Bucharest in 2012, ways forward in this process, setting a "Road Map" presented by the participating European countries. Once certified protection, the way of technological transfer is already done. And there are many variations of capitalization, such as sales, licensing, but do not forget the possibility of innovative product development by start-up company created by the researcher again inventor. And here we have an important role in the state and its policies to create the infrastructure for research and technology transfer by creating technology and business incubators, science parks, Centre for Research and Development, Technology Transfer Centre performance and the possibility to exchange ideas and innovative products brokerage activities at national or international level, trade fairs, exhibitions and scientific events. Technology transfer is the introduction or acquisition in the economic circuit of the technology and specific machines, equipment and facilities resulted from research, in view of new or improved processes, products or services, required by the market that induces an innovative behavior, including the disseminate information, to explain, to transfer knowledge, to provide consulting and communicate with people. This is carried out by the network of innovation and technology transfer entities (ARoTT or ReNITT). The infrastructure of Innovation and Technology Transfer was created and is functionally assessed and accredited by the National Authority for Scientific Research (ANCS) under GD no 406 /2003 and aims to support economic and social development, foster innovation and technology transfer, attract investment to capitalize results of research and innovation, as well as human resources from the national research and development system. Its role is to support SMEs and the interface between them, as beneficiaries and producers of innovation, "inventors‖ (natural or legal persons) represented by universities,
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research institutes and companies with research and development activity. Innovation and invention support structures and services have to develop their own type of management, with planning and policies depending on the circumstances prevailing in each country.
References [1] Rothwell, R. Towards the Fifth-generation Innovation Process. International Marketing Review, vol.11, No.1, (1994), pp.7-31. [2] Le Corre, A., Mischke, G. The Innovation Game. A New Approach to Innovation Management and R&D, Springer US (2006). [3] Galanakis, K. Innovation process. Make sense using systems thinking. Technovation, november, (2006), pp.1222-1232. [4] Gann, D., Dodgson, M. Innovation Technology: How New Technologies Are Changing The Way We Innovate, National Endowment for Science, Technology and the Arts, London, (2007). [5] Savescu, D. Some aspects regarding the concept „Research and Business”. Journal of Industrial Engineering and Management, JIEM, Vol. 3 nr.2, (2010), pp. 337-352. [7] Savescu, D. Aspects regarding the connection between the technologic transfer and regional development. 2nd International Conference on Applied Social Science, ICASS 2012, Kuala Lumpur, Malaysia, Vol 2, (2012), pp. 345-351, published by IERI- Information Engineering Research Institute-SUA.
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THE COROSION OF THE WELDED JOINTS ON METALAL PIPES
Drd.ing C. MIHAI, prof.dr.ing. R. N. DOBRESCU, prof.dr.ing. N. POPA University of Pitesti, 1 Targu din Vale St., 110040 - Pitesti, Romania Corresponding author‘s e-mail address: [email protected]
Abstract: This paper present the results of a research concerning the corrosion of the welding zones of the pipes used for the circulation of the technological water in an oil extracting installation. In the first part, the authors present the characteristic of the materials existing in welding zone and of the technological water, general considerations concerning the electrochemical process that is developing as effect of the contact between the metal and the liquid, with a specific chemical composition. The comparison between the recommendations for the welding procedure exiting in the quality norms and the reel quality of the welding zones of the pipes indicate a good concordance. In this case, the conclusion who results is that the environment conditions are very aggressive, and their effects require the continuation of the research.
Key words: corrosion, conditions are very aggressive, macroscopic evaluation
1. Introduction The subject of this paper is to present a case study regarding the corrosive action of the existing compounds from the water reservoirs (after this is used in oil exploitation from the oil fields) on the pipe that pumps it from the collection park to the pumping station. Initially, the pumping water from the oil fields is considered having the chemical composition close to the analyzed one on a sample token from the oil field and part of the pipe project.
Table 1. The water expected chemical composition, mg/l pH Sulphides Suspensions Extractable Dissolved Ca Chloride Density 3 (H2S) oxygen hardness [g/cm ] 5.25 3.4 23.0 74.0 0.0 1380 8765.0 1.07
According to the soil layer from the oil field, the initial chemical composition of the reservoir water can be modified as to add salt and other compounds in a tank from the collection park. The water circuit scheme is presented below:
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From the three phase separator, the oil products are recovered. The saltwater that remains at the bottom, due to its great value density is pumped back into the station. And the cycle repeats. After the soil recovery and the chemical analysis made on two samples of water, the compounds values are shown in table 2.
Table 2. The chemical composition of the recycled water samples
I, % -expanded uncertainty for k = 2 and trust level P = 95% CMA – predicted chemical composition of the reservoir water
Through the pipe that pumps the saltwater from the collection park to the pumping station in the oil field, the designer has provided a pipe L 245 NB brand, with 88,9 mm diameter and wall thickness of 6,3 mm, pre-insulated outside with extruded polyethylene. The steel used to produce the pipes has a good weld ability of L245MB (W 1.0457) and the following standard chemical composition:
Table 3. Steel L245NB (standard chemical composition, %, According to SR EN 10208-2 + AC/2009)
C Si Mn Ni P S Cr Mo N Al Cu Other max. max. max. max. max. max. max. max. max. max. 0.015 0.16 0.40 1.10 0.30 0.025 0.020 0.30 0.10 0.012 – 0.25 < 0.060 0.42
The pipes welding used the WIG procedure (wolfram inert gas). In order to make the welding happen, rods with 2,4 mm diameter Böhler DMO-IG (W2Mo) type were used, presenting the following standard chemical composition. Standard chemical composition of the addition material (%, According to EN ISO 636-A:2008)
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C max. Si max. Mn max. Mo max. 0.1 0.6 1.2 0.5
Comparing the chemical compositions drawn by the above tables and taking into account the addition material producer recommendations, specified in the product technical sheet, we can conclude that the alloy used as the addition material is compatible with the pipe steel. The welding process had at its base a procedure detailed specification, drawn after it correspond to the qualitative request of norm EN ISO 15614-1, registered by a certified authority (TUV) and a qualified welder for the relative procedure in the norm EN 287 requests field. The tubes taken from the welding sample were put to the following tests, in order to qualify the procedure: test to transverse tensile test to transverse bending test to contact bend hardness test macroscopic evaluation
2. General considerations It is well known that, at the air temperature, any metallic material is covered by an oxide film. When contact an acid watery solution, this can be completed dissolved and the metallic surface becomes active. In a neutral solution, the oxide film solubility can be lower than in an acid solution, which makes the dissolution to be less extended. Thus, the metal underneath the oxide film is exposed, at first only in some points, where inclusions at grains limit from the metal structure can be found. As the dissolution process evolves, the metal surface is totally exposed to the watery solution contact [2]. In this stage, the metallic material corrosion process begins, its atoms passing into the solutions as positive ions, which lead to negative charges (residual electrons) accumulation in the metallic mass and the potential difference increase between the metallic material and the watery solution. Thus, the metallic material corrosion in these conditions can be regarded as an electro-chemical process [1, 2, 3 ,4].
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Fig. 1. The corrosion process scheme for a metallic material in contact with a watery solution [3]
In case of the corrosion action acting in the welding cords, this is emphasized by this area remaining existing tensions, if the thermal treatment for the welding cords was not performed. Over the electro-chemical corrosion process overlaps a corrosion process under pressure. 3. Existing situation description The corrosion process that makes this paper study object had special effects on the existing welding cords in the pumping pipe construction for the salty water used on the exploitation process of fie oil field, by penetrating this cords from the inside to outside. First perforations were seen at only 15 months from the pipe operation start. Water infiltrations at the soil surface have appeared where the pipe was buried (approximately 1.7 m depth). First were suspected the welded joints, due to the fact the soil area was known as rich in chlorides and also because the pipe construction project was about to replace the old pipe that was very often penetrated. Less than 2 years after new pipe release, 35 of the 95 joints were cut and restored. As a first observation, all the welding cords are affected at the bottom, meaning ―between 5 and 7‖ if we think about a clock image. The welds were radiographed during the pipe execution and the control results did not point out any faults.
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4. Micro and macro aspects of the corrosion areas
Corroded Breakdown areas from cord the cordon root
Corroded areas from the cordon root
Fig.2 In order to analyze the corrosion phenomenon in the welding cords areas, chemical analysis was made. Thus, the basic materials on one side and the other of the welded joint, as well as the deposited metal were analyzed. Comparing the results obtained with the ones specified in the quality certificates, we can see there are no significant differences between them and so, there is no need and proof in replacing the materials.
Table 4. Chemical composition of the welded joint materials, %
Sampl C Si Mn P S Cr Mo Ni N Al Cu Other e nr. MB1 0.14 0.30 0.72 0.010 0.006 0.06 0.02 0.07 0.0098 0.028 0.12 0.29 MB2 0.15 0.29 0.75 0.014 0.006 0.06 0.03 0.06 0.0100 0.030 0.09 0.30 MD 0.09 0.58 1.12 0.006 0.011 0.02 0.49 0.01 0.002 0.004 0.02 - Also, on the tubes taken from the non-corrosion areas of the pipe welded joint, bending attempts on mandrel were made, according to EN ISO 5173, with the weld root stretched and compressed. There were not observed rifts in the welded joint on neither of them.
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Fig.3.
The conclusion is that the joint has a plastic character; it does not present breakable areas, so during the welding process there were no burning phenomena.
5. Probable causes of the welded joints corrosion a. Large amount of chlorides in the reservoir water from the area where the pipe is placed. These chlorides amplify the electro-chemical corrosion phenomenon described above. b. The pipe is not always full of water, only when the water pumping between the park and the injection station is considered necessary. Salty water is always in the bottom of the pipe, and at the top there is air when the pipe is not in function. In this situation, the chemical oxidation reaction is accelerated, due to the air and salty water environments. c. In the reservoir water there is, according to the chemical analysis, particulate matter which, trained by the fluid (water) that runs through the pipe, makes happen the metal molecules detachment, as the sanding phenomenon. d. The weld root protuberances are practically opposed to the water smooth flow that leads to the permanent hitting from the pumped jet and in the end to the root destruction. e. The attempt pressure of the pipe, made before its operation, was: Pinc.=50 bar, time of 6 hours. The sealing with water test was made at: Pe=44 bar, time of 24 hours. In these conditions, any small imperfections of the welded cord inside the pipe are amplified (and especially the ones from the bottom where the welding position is the most un-favorable even for an experimental welder), the phenomenon of rift corrosion under pressure appears, that can become one of the causes of propagation and acceleration of the welded deposited material erosion. f. As it is known, the structure of the metal made by welding is similar to a fount structure, in our case ferrite-pearlitic type, with ferrite dendrites oriented on the cooling after solidification thermal flow. After welding, without a normalization thermal treatment, the structure has remained rough, with large grains easily detaching in the operation conditions of the pipe.
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6. Conclusions Taking into consideration the causes we have presented at chapter 4 and the table below recommendations (2nd column to be observed), the welded cords corrosion of the pipe is not due to welds faulty execution, but it has to be treated as a complex process even in the design phase. The welding procedures qualified by the competent authorities (TUV, ISCIR, etc.) after international norms, take into consideration only the mechanical characteristics of the welded joint, with no attention to the environment where the joint operates. The working environment aggression effects tests are not available for the moment in many laboratories from our country.
Corrosion Resistance 1)Good 2) Be Careful 3) Not Useable Metal 302 and 316 Cobalt 416 Fluid Carbon 304 Hasteloy Hasteloy Cast Iron Stainles Bronze Durimet Monel Titanium base Stainles Steel Stainles B C s Steel alloy 6 s Steel s Steel Chlorine 3 3 3 3 3 3 3 3 2 1 2 3 gas, wet Chlorine, 3 3 3 3 2 2 3 3 1 3 2 3 liquid Sodium 3 3 2 2 1 1 1 1 1 1 1 2 chloride Water, 2 2 2 2 1 1 1 1 1 1 1 3 sea
References
[1] Kruger, Jerome: Electrochemistry of corrosion, published in Electrochemistry Encyclopedia, available online http://electrochem.cwru.edu/encycl/art-c02-corrosion. htm [2] Lower, Stephen: Electrochemical corrosion, published in ChemWiki: The Dynamic Chemistry E-Textbook, chapter 7 Electrochemistry, available online http://chem - wiki.ucdavis.edu/Analytical_Chemistry/Electrochemistry/Electrochemistry_7%3A_Electroch emical_Corrosion [3] Nave, R.: Corrosion as an Electrochemical Process, available online http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/redoxea.html#c1 [4] Thomas, J.G.N.: The electrochemistry of corrosion, edited by Gareth Hinds from the original work, available online http://www.npl.co.uk/upload/pdf/the electrochemistry of corrosion.pdf [5] The Engineering ToolBox: Metals and Corrosion Resistance
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EFFICIENT DIRECTIONS OF DEVELOPMENT OF METHODS OF MECHANICAL PROCESSING OF MATERIALS
Director PhD. Оlеg KLЕNОV1, Project Director PhD. Grygoriy NOVIKOV2 1DiMerus Engineering Ltd., [email protected], 2Elbor S&T Co., [email protected] Kharkov, Ukraine
Abstract: The analytical dependencies for determining the main parameters of machining are given: the processing capacity, the nominal cutting stress (energy intensity of the treatment), the cutting temperature, the thickness of the heated layer of the processed material during blade machining and grinding. Theoretically, it is shown that the energy consumption of the processing is less than that when grinding, and the most efficient processing scheme, taking into account the processing precision limitation determined by the amount of elastic movement in the technological system, is the grinding scheme without transverse feed with a given initial interference in the process system.
Keywords: machining, grinding process, processing capacity, conditional cutting stress, cutting temperature, elastic displacement value.
1. INTRODUCTION The creation of modern competitive machine-building products requires a wide application of new science-intensive technologies of mechanical and physicotechnical processing of materials that ensure a multiple increase in labor productivity, quality, precision and cost-effectiveness in the manufacture of parts and machines [1, 2]. Processing of metals by cutting has received wide practical application due to low energy intensity of the process and high quality and productivity indicators in comparison with physical and technical methods of processing. Particularly effective was the use of metal machining in connection with the creation of high-speed machine tools with CNC machining center type and prefabricated carbide and ceramic blade tools with wear-resistant coatings [3]. However, in order to effectively implement the cutting process in each particular case, it is necessary to use the optimal processing conditions that ensure a reduction in the strength and thermal tension of the process. This requires the creation of theoretical fundamentals of mechanical processing that allow us to analytically solve optimization problems to substantiate the most promising methods and processing conditions without involving empirical approaches that require the implementation of labor-intensive and long-term experimental studies.
2. ANALYTICAL RESEARCH To assess the main most effective areas for the development of machining, an analysis of the analytical dependence should be carried out to determine the processing capacity: P Q S V z V , (1)
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2 where S is the cross-sectional area of the cut, m ; V - cutting speed, m/s; Pz - tangential component of the cutting force, N; - conditional cutting voltage, N/m2. Increase the productivity of processing Q by increasing the parameters S and V or increasing, Pz , V and decreasing . The increase in the tangential component of the cutting force Pz is the implementation of power cutting, and the increase in the cutting speed V is the realization of high-speed (high-speed and ultra-high-speed) cutting. Reduction of the conditional cutting voltage - the control of the process of chip formation during cutting and, first of all, the contact processes occurring on the working surfaces of the tool. The conditional stress of cutting is described by an analytical dependence:
2ct tg , (2) where is the compressive strength of the material being processed, H/m2; - conditional ct friction angle on the front surface of the tool ( tg f - coefficient of friction); - the front corner of the tool. Reduce the conditional cutting voltage by decreasing the angle , i.e. Reduction of the conventional friction angle (friction coefficient f) and an increase in the front angle of the tool . Under certain conditions, 0, which can significantly reduce the nominal cutting stress and increase the cross-sectional area of the shear S and the processing capacity Q. However, the increase in S when cutting by cutting tools is limited by the strength of its cutting part. Therefore, an increase in the cutting speed V, according to the relationship (1), should be considered as the more preferable way of increasing the processing capacity Q. As is known, as the cutting speed V increases, the friction coefficient f on the front surface of the tool decreases, which contributes to the reduction of the nominal cutting voltage and the increase in the processing capacity Q. The average temperature of the formed chips is determined by the approximate dependence: , (3) h с 1 a where c – is the specific heat of the processed material, J/kg ∙K; - density of the processed material, kg/m3; а – is the thickness of the cut, m; h - thickness of the heated layer of the treated surface, m; h , (4) a c a V tg
- coefficient of thermal conductivity of the processed material, W/m∙K; - the conventional angle of shear of the processed material. With an increase in the cutting speed V, the conventional shear angle of the material being processed increases, and the ratio h/a decreases. Consequently, the amount of heat 157 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
leaving the workpiece decreases and the amount of heat that flows into the resulting chips increases. The average chip temperature (equal approximately to the surface temperature of the workpiece) with increasing cutting speed V increases, asymptotically approaching the value / с (Fig. 1) because of the addition (1+h/a) 1. This is the essence of the physical effect of high-speed and ultra-high-speed cutting performed with cutting speeds in excess of 100 m/s, since in this case the temperature of the surface layer of the workpiece remains virtually constant with increasing of cutting speed V. It should be noted that traditional methods of processing with blade tools realize cutting speeds, as a rule, not more than 2 m/s. As the experience of the leading foreign machine-tool companies shows, the transition to the high-speed cutting area allows to increase the processing capacity by more than 10 times while improving the quality and accuracy of the machined surfaces, which is a cardinal solution to the problem of machining materials. For the practical implementation of these processing processes, it is necessary to create domestic machines that operate at cutting speeds of the order of 10,000 m/min. This will be an important step in raising production, improving the competitiveness of machine-building products and increasing labor productivity.
с
0 V Fig. 1. Dependence of surface layer temperature machined part from the cutting speed V.
The revealed regularities are valid at cutting of metal materials. When cutting nonmetallic materials, almost all the heat goes to the heating of the cutting tool. In this case, the increase in cutting speed is limited and is determined by the level of the process strength and the heat removal conditions from the cutting zone, i. e. Thermal conductivity of instrumental material. When grinding materials, in connection with the negative front corners of the cutting grains of the circle, the dependence (2) takes the form:
2сt tg . (5) Under the condition 900 , we have tg (Fig. 2). To reduce the conventional cutting stress , it is necessary to reduce the angles and , using effective technological media (reducing the coefficient of friction), providing high sharpness of the cutting grains, etc.
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Comparing the dependences (2) and (5), it can be seen that under the blade treatment the conditional cutting stress is less than in grinding. When grinding, the total instantaneous cross-sectional area of the cut is less than all the simultaneously operating grains S Q / Vc and, accordingly, the processing capacity Q. Therefore, to increase Q, one can increase the speed of the circle Vc . In general, when grinding materials, the productivity of processing Q is determined by the dependence: P V К 2 Q y c gr , (6) 2сt where P – is the radial component of the cutting force, H; К P / P - coefficient of y gr z y grinding.
2 сt 3
2
1
о 0 22,5 45 67,5 ,
Fig. 2. Dependency ratio / 2сt from the corner .
Proceeding from the dependence (6), it is possible to increase the productivity of the processing Q, first of all, by increasing the grinding factor К gr due to the increase in the cutting ability of the wheel ( К varies within f ... 1, where f is the coefficient of friction of gr the grain of the wheel with the material being processed). Parameters P and V have the y c same effect on the processing performance of Q, i. e. Effectively use both power (deep) and high-speed (ultra-high-speed) grinding. The effect is enhanced in case of combining deep and high-speed grinding. It should be noted that at present the leading foreign machine-tool companies have mastered the production of grinding machines operating at cutting speeds of 300 m/s. Machining processes are extremely complex and little studied. Unfortunately, even now there is no clear scientific understanding of the mechanics of the behavior of the technological system during processing. This limits the ability to design new machines and create highly efficient processing methods. To develop new solutions, it is necessary to move from traditional empirical to scientific analytical approaches, using the enormous achievements of 159 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
science in the field of mechanics of deformed systems. For example, by calculating the amount of elastic displacement y and the productivity of processing Q with round external grinding, it was possible to obtain an interesting and important solution:
Q Qnom Qnom Q0 e ; (7)
y ys ys y0 e , (8) y V К с where Q - nominal processing capacity, m3/s; Q 0 c gr - processing capacity nom 0 3 when the initial tension in the process system is reached y0 , m /s; Vc - speed of the wheel,
Vc Kgr c Qnom m/s; c - rigidity of the technological system, N/m; ; ys - Ddet ldet Vc Kgr c steady-state value of elastic displacement in the technological system, m; Ddet , ldet - diameter and length of the workpiece, m; - processing time, s. The nature of the change Q and y over time processing is shown in Fig. 3a, b. For
Qnom Q0 and ys y0 , the conditions Q Qnom and y ys (curve 1) are satisfied. For
Qnom Q0 and ys y0 , the conditions Q Qnom and y ys (curve 3) are satisfied. For
Qnom Q0 and ys y0 , the conditions Q Qnom and y ys (curve 2) are satisfied. Q
Q0 y0 1 1
2 y 2 Qnom s 3 3
0 1 0 1 а Q
y0 Q0
0 0 c Fig. 3. Dependence of processing performance (a, c) and the elastic displacement (b, d) of the processing time.
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The average processing capacity over time 1 for the three curves presented in Fig. 3a, will be different. So, if a family of curves is drawn Q through a fixed point with coordinates Q , 1 then the greatest average processing capacity will be provided under the condition ys y0 , and the smallest - under the condition y0 0 (Fig. 3b). Obviously, the greater the initial interference in the process system y0 , the greater the average processing capacity. From the transformed dependence y ys 1e y0 e (8): it follows that the maximum value y0 (for given values of y and 1) is achieved under the condition ys 0 . Consequently, the most efficient processing scheme, taking into account the limitation in the processing accuracy (determined by the amount of elastic motion y ) is the grinding scheme without transverse feed Qnom 0 with initial interference y0 in the process system. Current values Q and y in this case are determined by the dependencies (Fig. 3c, d):
Vc K grc Ddet ldet Q Q0 e ; (9)
Vc K grc Ddet ldet y y0 e . (10)
The higher the value Vc , Kgr , с and the smaller y0 , Ddet , ldet , , the faster the specified accuracy of processing is achieved. Obviously, the largest value y0 can be equal to the value of the allowance being removed П . To fulfill this condition, starting from the dependence (9), it is necessary that the maximum possible processing capacity, due to the cutting properties of the grinding wheel, be equal to or commensurate with the value under the condition [4]. Dependencies (9) and (10) describe the "ideal" cutting scheme from the point of view of ensuring accuracy and processing capacity, i.e. The cutting scheme, which in the future can become the main in the machining of materials. From the data given, it follows that by creating a preliminary tightness in the technological system y0 , it is possible to realize the condition Q Qnom . It should be noted that machining according to a rigid scheme (curve 2 in Fig. 3b) leads to an increase in the amount of elastic displacement (a decrease in the accuracy of processing). Consequently, the methods of processing blades and abrasive tools that are applied in practice in a rigid scheme from the point of view of ensuring the accuracy of processing are inefficient. It is necessary to use a scheme without feed with an initial radial movement, reducing the allowances for processing and limited to finishing operations with the use of abrasive and blade tools. In fact, the hard cutting schemes used in practice are a necessary measure in connection with the need to remove relatively large allowances.
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3. CONCLUSION The analytical dependencies for determining the processing capacity, the nominal cutting stress (energy intensity of the treatment), the cutting temperature, the thickness of the heated layer of the processed material during blade machining and grinding which are the main parameters of machining are given. Energy consumption of the machining processing is theoretically shown and analyzed taking into account the processing precision limitation determined by the amount of elastic movement in the technological system.
REFERENCES [1] Starkov, V. K. Grinding with highly porous wheels. Moscow, Mashinostroenie, 2007, 688 p. – In Russian. [2] Yakimov, A. V., P. T. Slobodyanik, and A. V. Usov. Thermal physics of mechanical treatment. Kiev&Odessa, Lybid, 1991, 240 p. - In Russian. [3] Zhovtobryukh, V. A. Directions of effective application of modern metal-cutting tools. Physical and Computer Technologies. Proceedings of the 22nd International Scientific and Practical Conference, December 7-9, 2016, Kharkov. Dnepropetrovsk, Publishing house ―Lira‖, pp. 22-28. – In Russian. [4] Yakimov, A. V., F. V. Novikov, G. V. Novikov, B. S. Serov, and A. A. Yakimov. Theoretical bases of material‟s cutting and grinding. Odessa, Odessa Nat. Polytech. Univ., 1999, 450 p. – In Russian.
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INFLUENCE OF MACHINING ON QUALITY PARAMETERS OF OPTICAL METAL PRODUCTS
Sen. Lecturer PhD. Valentin SHKURUPY Simon Kuznets Kharkov Nat. Univ. of Economics, [email protected] Kharkov, Ukraine
Abstract: The article gives recommendations about the technological support of the given optical characteristics of metal products. The main task at providing light reflectance of surfaces is smoothing of roughnesses on a surface and providing surface cleanliness. The criterion of surface roughness and the work function of electrons have the greatest connection with the performance characteristics of optical metal products. The surface properties are determined by the double electric layer at the surface. Each subsequent stage of abrasive polishing should be carried out with a smaller grain size of an abrasive of not more than Rmax roughness, obtained in the previous stage.
Keywords: surface, processing, method, roughness criterion, electron work function.
1. INTRODUCTION Technological support of the optical characteristics of parts working in the conditions of direct exposure to solar radiation is realized by the finishing processes. Among finishing machining processes there is a specific area of abrasive polishing of materials [1], which is the only effective way of forming a surface layer with minimal values of the height parameters of the surface roughness. The main task when polishing is to smooth the roughness on the surface.
2. ANALYTICAL RESEARCH However, a number of details have operating requirements where the estimation of the height parameters of the surface roughness is insufficient. This particularly applies to the details of aircraft. Among them are the ones that should have high reflective ability of surfaces, high light-absorbing and emissive capacity (details of outer shells of aircraft, details of thermoregulating devices, etc.). Control over the processing of such surfaces is carried out through parameters of the geometric and physico-chemical state of the surface layers (criterion for surface roughness and work function of electrons). Recently in connection with the increase in the tactical and technical characteristics of aircraft, especially military applications, more and more find application of a product with special properties of surface layers in their constructions. Manufacturing of parts and assembly units of aircraft with specified optical characteristics of their surface layers allows to solve the problem of minimizing their mass, temperature deformation of structural elements while simultaneously increasing their dimensional stability. details of aircraft Typical examples are the details of aircraft in thermal control systems for compartments with on-board equipment, reflectors for laser mirrors, retractable rods, antennas, etc. The properties of the surface layers of such parts will be determined by the geometric characteristics and the physico-chemical state of these layers.
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Nanotechnologies open up great opportunities. The use of nanotechnologies is especially important in the production of precision parts of machines such as metal mirrors for laser technology which are widely used in sections of the working path of the laser beam. They should have a high reflectivity, for example, over 99 % for copper mirrors, and the height of surface irregularities should be 5 - 3 nanometers. Working surfaces of aluminum substrates of electronic devices, details of adaptive optics, gyroscopic devices should have nanometric dimensions of unevenness. Therefore the application of nanotechnology processing, which provides the necessary parameters of the surface layer of parts, is very relevant for engineering. Thus the study of the influence of processing methods and in particular abrasive polishing on the quality parameters of optical surfaces as well as the creation of new technological processes for the manufacture of articles with special properties of surface layers are very urgent tasks. Thus the goal of the work is the development of technological recommendations for abrasive polishing of optical surfaces.
Research objectives. The work is based on the following formulated research objectives: - systematization of structural and technological solutions for precision machining of metal surfaces; - highlight the parameters of the machined surfaces of metal products, which have the greatest connection with the operational optical characteristics of the details; - to develop a theoretical approach to determining the technological conditions for providing quality parameters for abrasive polishing of parts based on surface quality parameters (surface roughness and its physico-chemical state); - to develop recommendations for smoothing out surface irregularities, for minimizing the altitude parameters of surface roughness on the basis of the method of complex evaluation of the surface quality of optical metal products.
Results of the research. Classification of processing methods by technological impact showed that abrasive polishing can be attributed to technological systems associated with a slight change in the substance in the surface layers of the parts (Fig. 1) and the classification of processing methods by the nature of the impact on the subject of labor (Fig. 2) shows that the implementation of the polishing process by the high-speed movement of the working medium relative to the surface being processed is poorly studied.
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Fig. 1. Classification of technology by the nature of the impact on the subject of labor.
Fig. 2. Classification of methods of treatment with free abrasives by the nature of the impact of an abrasive particle.
The processing methods determine the limits of the change in optical characteristics, and this makes it possible to choose a method for processing the surfaces of aircraft parts. Fig. 3 shows the change in the maximum reflectivity of the surfaces for the aluminum alloy AMg6 after processing by various methods. In this case, the nature of the change in the ratio of absorption to radiation will also be determined by the methods of processing.
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Fig. 3. The nature of the change in the light reflectance and surface parameters from the processing methods of AMG-6 alloy parts: 1 - rolling; 2 - hydroabrasive treatment; 3 - processing with metal shot; 4 - milling with carbide cutter; 5 - milling with a milling cutter from an electromotive bushing; 6 - turning a carbide-tipped tool; 7 - diamond polishing; 8 - smoothing; 9 - diamond turning.
We have established the character of the change in the ratio of the optical characteristics and geometric parameters of the surface from the methods for processing details from the AMg6 alloy (Fig. 4). For aircraft parts for the thermal regulation of compartments of onboard equipment, the ratio of absorption to radiation should approach unity, i.e. The absorbed energy must be radiated and in this case the surface should not be heated.
Fig. 4. Dependence of the ratio of absorption to radiation from surface treatment methods: І - milling; ІІ - hire; ІІІ - turning, ironing; ІV - diamond turning; V - enamels AK-512, EF-1118; VI black chrome; VII chemical milling + anodizing.
And what happens with the geometric and physico-chemical state of the surface? The processing of super-smooth, precise metal surfaces has its own specific features related to its electronic structure. Free electrons in violation of the crystal lattice in the boundary layer exit the surface and form a so-called double electric layer, which determines the properties (conductivity) of the upper boundary layer. Moreover, the presence of a double electric layer also determines the oxidation processes on the metal surface, that is, the 166 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
formation of nonmetallic conductivity membranes, on which the properties of the upper boundary layer of the metallic surface depend. They can be much larger in thickness than the roughness of the treated surface. In connection with the foregoing, the formation of a double electric layer on a metal surface determines the degree of disruption in the crystal lattice of the metal and can be a measure of its defectiveness. These changes on the surface can be quantified by measuring the work function of the electron, which determines the amount of work on the movement of electrons on the surface of the metal. Taking into account this circumstance, we proposed to control the state of the surface layer after cutting by estimating the surface parameters from the work function of the electron (WFE), since it is sensitive to changes in the physical and chemical state of the surface. The theoretical positions developed by us, in contrast to the existing ones, consist in establishing the relationships between performance characteristics and technological parameters with the help of integral parameters of the surface layer: the roughness factor and the work function of the electron. When establishing the relationships, the surface roughness parameters and the roughness factor F [2] were chosen as geometric parameters, and the parameters of the physical-chemical state of the surface were taken to be: structure, phase state, chemical composition of phases and thickness of the non-metallic membrane. The roughness factor F and the value of the work function of the electron respectively for geometric and physicochemical characteristics were chosen as the integral parameters of the mismatch. To clarify the procedures for the use of integral parameters mismatch F and consider the edge layer. Roughness factor indicates the ratio of the square smooth trailing part of hollows to square rough part of basin F = Fg / Fw It takes into account not only the height of roughness, the height of submicrocavity, but the shape and completeness of the depressions (protrusions) of the roughness [2]. In practice, this factor is determined from the profile diagrams being analyzed and electronic images. Analysis of roughness factor values on surfaces of parts after different treatment showed that at the height of the roughness Rz ≤100 nm its magnitude is almost equal to 1. So it can be used as an integral parameter in obtaining roughness height at least 100 nm. At the same time reducing the roughness height less than 100 nm integral parameter mismatch adopted value of RWE, which in practice is measured through the amount of contact potential difference (Fig. 3, Fig. 5).
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Fig. 5. Dependence criterion of surface roughness and the KRG from alloy machining methods AMg6: 1 - rolling; 2 - processing with metal shot; 3 - hydroabrasive treatment; 4 - milling with carbide cutter; 5 - milling with a milling cutter from an electromotive bushing; 6 - turning a carbide-tipped tool; 7 - polishing diamond; 8 - smoothing; 9 - microcurrents with a diamond cutter.
Studies have shown that the value of RWE can evaluate any change in physical and chemical status of surface processing. In practice, in nanotechnology processing of machine parts, both abrasive and blade processing are used [3]. Technological media based on ultradisperse alumina abrasives (UDD), which are obtained by gas-dispersed synthesis (GDS), are developed for nanoscale treatment. The essence of this is the synthesis of UDD in the combustion zone of a laminar two-phase torch of gas suspensions of metal powders in oxygen-containing gas. At the same time, the capabilities of the metal-oxygen system are fully realized and high temperatures are obtained, which are necessary for the synthesis of metal oxides due to heat release from intrinsic chemical reactions. UDD parts are spherical in shape with a diameter of about 100 nm. Smoothing effect that provides abrasive slurry with the presence of spherical abrasive allows to reduce cutting- scratching the surface and go to the micro-roll effect and so ensures tall 5 - 3 roughness nm. To assess the impact of processing methods on the surface layer, we assessed the criterion of surface roughness (F) and the electron work function (if) for details of the alloy AMg6 (Fig. 5). It is established that when surface surfaces are pretreated in order to achieve minimum values of the height parameters of the surface roughness, the control of the treated surface must be carried out by evaluating the roughness criterion of the surface, and after the final processing methods, the control of the treated surface must also be carried out by 168 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
estimating the work function of the electrons (estimates of the values of the contact potential difference - PSC). One of the drawbacks of abrasive processing is the effect of currently used abrasive compounds on the physicochemical properties of the treated metal surface associated with oxidation processes. This is explained by the fact that at this type of treatment free electrons appear, leading to oxidation of the surface layer. The thickness of the resulting oxide film, as a rule, is much larger than the height of the irregularities on the real metal surface. Therefore the main task at providing light reflectance of surfaces is smoothing of roughnesses on a surface and maintenance of cleanliness of a surface from pollution. The change in the height parameter of the surface roughness during polishing is shown in Fig. 6.
Fig. 6. Dependence of the height parameter of the surface roughness on the time of polishing with abrasive materials of different granularity
Dependency analysis (see fig. 6) shows that: - the time of stabilization of the process of formation of the altitude parameter of the surface roughness depends little on the grain size of the abrasive (from M3 to M28); - the time of stabilization of the process of formation of the altitude parameter of the surface roughness decreases substantially with a decrease in the height parameter of the initial roughness of the surface before processing; - for each granularity of the abrasive material, there is a limit to stabilizing the values of the altitude parameter of the surface roughness, and this is very important when assigning a sequence of use of working media when smoothing the surface layer of the parts.
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3. CONCLUSION 1. Industrial abrasive processes and practical recommendations for their effective use do not provide the required smoothing of surface irregularities and very small values of the height parameters of the surface roughness of parts with optical characteristics. 2. Promising directions for the further development of abrasive processing in order to achieve super-smooth surfaces of parts with optical characteristics should be considered metrological assurance of quality control of processing, selection of appropriate technological environment and development of a control system for the process of shaping the surface layers of parts.
REFERENCES: [1] Abrasive and diamond processing of materials. Ed. by A. N. Reznikov. Moscow, Mashinostroenie, 1977, 390 p. – In Russian. [2] Shkurupy, V. G. Increase of efficiency of technology of finishing processing of light reflecting surfaces of details from a thin sheet and tapes. PhD Thesis of Techn. Sc. Odessa, Odessa Nat. Polytech. Univ., 2006, 21 p. – In Ukrainian. [2] Tsesnek, L. S. Mechanics and microphysics of abrasion of surfaces. Moscow, Mashinostroenie, 1979, 264 p. – In Russian.
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ON THE QUALITY CONTROL OF THE FUEL FILLER FLAP LINING MARK
PhD.Lecturer Monica BÂLDEA,University of Pitești,Faculty of Mechanics and Technology,Târgu din Vale Street,no.1,Pitești,Romania,[email protected] Ph. D. Lecturer Ancuţa BĂLTEANU, University of Piteşti, Faculty of Mechanics and Technology, Târgu din Vale Street,no.1,Pitești, Romania, [email protected] PhD.Lecturer Mihaela ISTRATE,University of Pitești,Faculty of Mechanics and Technology,Târgu din Vale Street,no.1,Pitești,Romania,[email protected]
Abstract: The paper provides solutions for the manufacture technological process quality improvement, by implementing a Poka-Yoke device at one of the mold work stations, and by reducing the time required for the manufacturing process by grouping two molds on a single press.
Keywords: fuel filler flap, quality, poka-yoke.
1.INTRODUCTION The mark Fuel filler flap lining, as shown in figure 1, is a bodywork component that is part of the assembly of a car, it combines with other elements such as the fuel filler flap and has the role to strengthen its resistance.
Fig.1.Fuel filler flap lining mark Fig.2 Fuel filler flap lining combined with fuel filler flap In order to reach the stage of final part, the ―fuel filler flap lining‖ goes through several operations:
- Perforation cutting (op 10); - Pressing (op 20); - Perforation (op 30); - Bending, flanging (op 40); - Perforation (op 50). 171 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
2. PROCESS IMPROVEMENT BY IMPLEMENTATION OF A POKA-YOKE DEVICE One of the main errors that may occur during the production process is the human nature. This error occurs either in the absence of familiarization with the process in question, oblivion, wrong reading of the visual signs, or out of lack of concentration on the operations to be carried out, things that lead to faults occurrence. From an analysis of the manufacture technological process for the " fuel filler flap lining" mark, it has been found that such an error occurred at one of the work stations, namely: at the first station of the multistation 1 mold, figure 3, during the operation 20 (Pressing) a human nature error occurred frequently, error which consisted in the wrong positioning of the workpiece in the mold, figure 4, error caused by the operator‘s lack of concentration or by his carelessness.
Multistation mold 1 Station 1+Station 2
Post 1+Post 2 Post1 + Post 2
Fig. 3.Mold 1
Correct Wrong positioning positioning
Fig.4.Workpiece positioning.
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The fault caused by this error led to the transfer of those parts to the scrap area, these being deteriorated beyond remedy. From a batch of 2000 parts, 10 % of these were considered scrap. In figure 5, we present the quality situation for the parts manufactured at the first workstation of the multistation 1 mold.
2000 parts batch
Fig.5 Situation before implementation
The stages of Poka-Yoke method implementation: 1) Identifying the problem One of the most common errors in the metal automotive components industry is the manufacture of noncompliant parts. For the product in question, this error turned up at one of the work stations, causing the occurrence of scrap parts.
2) Workstation analysis At the workstation, the operator carries out the pressing process of the part, obtained in the previous operation. After the analysis of this work station, it has been found that the error was caused by the wrong positioning of the workpiece, this being quite expensive and unproductive taking into account the fact that the part was included in the scrap area, being beyond any remedy.
(3) Development of Poka-Yoke solution Following the completion of the brainstorming for Poka-Yoke system development ideas and after selecting the best ideas, together with the manufacture and quality departments we have chosen as a solution, the implementation of a pin, Figure 6, which prevents the orientation of the workpiece in the wrong position. The main selection criteria were: implementation costs, performance time and implementation method.
4) Implementing the solution At this stage takes place the implementation of the pin in the mold workstation.
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Fig.6. Implemented pin
5) Tracking the implementation solution efficiency After the implementation of the pin, the semi finished product created at the workstation is checked in order to identify the fault for which the Poka-Yoke system was performed, tracking its effectiveness. In the creation of the Poka-Yoke system, the following general recommendations were taken into consideration: - the operator should work easier with the Poka-Yoke system than without it; - the Poka-Yoke system performed must not be perfect, it is important to be carried out at the right moment; - in case the Poka-Yoke idea improves with 50% the existing situation, it must be carried out on time and improved in time. After the implementation of the Poka-Yoke system, the situation has improved. The part, being always placed in the correct position, the number of faults reached 0. Figure 7 illustrates the graphic representation of the existing situation after this device implementation
2000 parts batch
Fig.7. Situation after device implementation
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3. PROCESS IMPROVEMENT BY GROUPING 2 MOLDS ON A SINGLE PRESS.
One of the elements of the production cycle duration is the work period. It consists of: - the preparation – completion time; - the time necessary to carry out the technological operations; - the time for the natural processes; - the time for internal transport; - the time necessary for the technical quality control.
For carrying out the operations 20-30, respectively 40-50 it is necessary to use two multistation molds . After analyzing the manufacture technological process for the "fuel filler flap lining‖ mark, in order to reduce the time necessary to carry out the 4 operations leading to the completion of the final part and to eliminate the time required for intermediate storage between workstations, together with the manufacture department , we have come up with an improvement solution. The molds having the same closed package were grouped on a single press. Thus, the 4 operations will be carried out at the same time - successively on two molds grouped on a single press, figure 8.
Fig.8 Molds grouped on a single press
Before the implementation of the new solution, the time required for operations completion on a mold was 8 seconds, the total time on both molds being 16 seconds, figure 9.
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Fig. 9. Time required for operations completion before this solution implementation
After grouping together the two molds on a single press, the time for operations performance was reduced to half, figure 10, its duration being 8 seconds for all operations.
Fig. 10 Total time required for operations completion before this solution implementation
Besides the fact that the duration of the manufacture cycle for the performance of the 4 operations was reduced to half, the intermediate storage was also eliminated.
4.CONCLUSIONS. Quality has increased by eliminating the fault occurring at one of the workstations of the mold, by implementing a Poka-Yoke device; The diminution of the time required by the manufacture technological process, was carried out by grouping the two molds together on a single press. The benefits of these solutions are the following: - The fault occurring at the workstation of the mold (incorrect positioning of the part by the operator) was eliminated by putting into practice the Poka-Yoke solution;
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- As a result of the abovementioned fault elimination, gains were obtained from an economical point of view; - The manufacture time for the "fuel filler flap lining" mark was reduced to half by putting into practice the solution of grouping the two molds on a single press; - The operations being carried out at the same work unit, the intermediate storage was eliminated; - The manufacturing costs have been reduced due to the grouping of the two molds, which has proved to be a cost effective solution from an economic point of view; - The use of a single press for the performance of the four operations necessary for the execution of the "fuel filler flap lining‖ mark ;
REFERENCES [1]Misiurek,Bartosz,Standardized Work with TWI: Eliminating Human Errors in Production and Service Processes. New York: Productivity Press. ISBN 9781498737548,2016 [2]Dobrescu,I.,Tehnologia presării la rece,Editura Universității din Pitești,2012 [3]Cazimir,B.,Eugen,N.,Tehnologia Construcțiilor de Mașini,Editura PIM,2008 [4]Grămescu,T,Chirilă,V.,Calitatea și fiabilitatea produselor, Editura Tehnică- Info,Chișinău,2001
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IMPROVEMENT FOR AN ASSEMBLY FLOW FOR A GIVEN COMPONENT (1)
Ph. D. Lecturer Ancuţa BĂLTEANU, University of Piteşti, Faculty of Mechanics and Technology, Târgu din Vale Street, no.1, Piteşti, Romania, [email protected] Ph. D. Lecturer Monica BÂLDEA, University of Piteşti, Faculty of Mechanics and Technology, Târgu din Vale Street, no.1, Piteşti, Romania, [email protected]
Abstract: This study is carried out in a line of assembly of a finite wiring product. The assembly of this finished product is done in two specific sections. For the analysis of the activities in the assembly section, the timing method of the work stations was used. On the basis of the work times obtained and their centralization, the Keizen method was subsequently applied to obtain an improvement in the installation flow. Finally, a reduction in working times was achieved, as well as a more ergonomic arrangement of jobs. This paper is the first in a series of 3 papers to deal with this subject.
Keywords: production flux, quality, improving flux, Kaizen
INTRODUCTORY CONSIDERATIONS The main purpose of the study is to apply the Keizen method to continuously improve the flow of a finished wiring product. In this study, which is carried out in three scientific papers, the finished product will be called wiring X and the Keizen continuous improvement method for the production flow To begin with, it can be said that manufacturing is the main component of production within the economic society with this specific. In this respect, the main purpose of manufacturing is to organize the activities in such a way as to ensure that the finished products are obtained in the best conditions. To that end, a series of technical measures are adopted, specific activities are being carried out and means are taken into account innovations in the field of science and technology. All these are used by an optimal combination of production means and labor. Finally, a rational, efficient and profitable use of the resources available to the production company studied is ensured. Manufacturing thus involves activities that involve the execution of products and works. These activities are done and programmed with the help of work objects and are ensured through the supply activity [1]. All the activities must meet the quality requirements and deadlines initially set in the plan.
USING THE KAIZEN METHOD IN THE STUDIED MANUFACTURING COMPANY The Keizen method or continuous improvement method is considered to be one of the most effective ways to improve or optimize a technological stream. The expression "keizen" means in Japanese continuous training, it comes from joining two words, namely "kei" -
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meaning continuity or change and "zen" - that is good or better. The Keizen method was chosen by the production enterprise under study due to the Keizen philosophy that an enterprise can not stay too long in a static position. At the same time, the Keizen method can be applied in the same way as change management, in the sense that the innovative approach must prevail. However, modernization, respectivelly adaptation to an active market economy, over- investment, or sudden and spectacular changes in technology processes or production techniques, which often occur with a return on ROI (Return On Investment) very low [2].
The goals pursued by applying the Kaizen method will be determined by a Keizen team. These goals refer to any factor that influences the production process, such as: the flow of materials, the size of stocks, space ergonomics, visual management, etc.
Achieving these goals is possible if the Kaizen team takes into account the following principles: to highlight actions that produce effects, both the process and its results must be taken into account; in order to avoid problems arising from the process under review, the process should be systematically addressed in its entirety and not just in a particular aspect of it; a non-critical educational approach will allow the review of current issues.
The implementation of the Keizen method also requires a major change in the organizational culture of the firm. Thus, the attitude and conscience of the hired, the top management staff and the new employees must change [3]. Keizen has to become something that all employees do, because they themselves want it, and because they know it's good for both them and the firm, and that's not because it's something coming from the leadership. In other words, Keizen means that if management is not ready to lead by its own example, the Keizen method can not be implemented. The human factor is the fundamental element that gives substance to the production process of any trading company. Improving the organization of production reveals the necessary presence and decisive contribution of people, both as organizers and as organizers. Thus, in studying and solving production problems, special attention must be paid to the knowledge of people from the psycho-social point of view, but also to the human problem solving only by human means. In this regard, employees must be treated as subjects and not as objects [4]. Based on these principles, managers can create a favorable psychosocial climate that stimulates, stimulates, mobilizes people to work and achievement, creativity and creativity. Achieving such a psycho-social climate requires an atmosphere that encourages and recognizes personal initiative, elements that facilitate the achievement of the production program.
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Mainly the Kaizen application rules are: corrections must be made as soon as errors have been identified. have to use their own knowledge to solve and eliminate errors. the question "why?" must always be used to find the right answers and to solve the problems that are best.
So the Keizen method has come to represent a daily activity, a continuous improvement system, used almost in any field. Being a continuous improvement process, Keizen can be applied to any area of the enterprise. In the case studied, the Keizen method will apply in an area where the Keizen team can better focus its efforts on reaching the main goal, namely continuously improving the flow of a finished wiring product [5].
ANALYSIS OF THE TECHNOLOGICAL FLOW FOR FINITE PRODUCT CABLE X For the finished product taken into study and referred to as X harness, the technological flow is made up of 3 modules, shown schematically in fig. 1.
1.1 2.1 Screwdriving Commissioning
3.1 Palleting
2.2 Video 1.2 Montage Module Module verification l 2 3.2 Delivery
1.3 Electrical 2.3 Packing check
Fig. 1 Technological flow diagram of the X reference
The following notations will also be used: MB - is carrying section of the modules ZSB - represents the final assembly section, Basis - represents standard wiring. Before the commissioning stage, the modules - and the prefabricated ones - and the materials needed for installation, will be selected for transport on the assembly line - fig. 2, so that they can be assembled later.
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Prefabricated storage racks
Label
Scanner
Fig. 2 Choosing and preparing materials for commissionin
Commissioning (1.1) is the operation by which the workstation is fed with the threads and materials necessary to obtain a Basis, according to the existing training list near the workstation - fig. 3.
The wiring harness attachement – the pane
Fig. 3 Charge station with yarns and materials
The assembly operation (1.2) is performed in both MB and ZSB.The assembly includes wire stretching, stamping and clipping activities. Thus, in MB, the bases are made by constructing the modules. In MB, the total of 354 staff is divided as follows: Table 1:
Table 1 MB staff categories Nr. crt. Category of staff Nr. people 1 Directly productive staff 270 2 Indirectly productive staff 42 3 Foreman 2 4 Group chief 10 5 Reserve 20 6 Preparatory 10 Total 354
The ZSB performs clipping, scraping, and verification activities. In ZSB, the direct productive staff is 865 people. The electrical check (1.3) of the harness X is carried out by means of an electric panel located at the end of the strip.
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After the first 3 operations of the first module, ie after the final wiring has been checked, it is sent to a stand, where it is screwed, video checked and packaged - in Module 2. The screwdriving operation (2.1) involves mounting screws on the harness by means of a screwdriver. Thus, a terminal is taken - depending on the X harness, which can be connected to the right or the left terminal - and by means of the machine, the respective harness is screwed in - fig. 4.
Fig. 4. Performing the screwdriving operation
Then proceed to the video verification (2.2), which involves checking the X harness with an instrument that checks the body wiring fuses. The confirmation or invalidation of the correct wiring harness installation must appear on the screen of the appliance - fig. 5.
Fig. 5. Perform video verification
The wrapping operation (2.3) is the last activity in module no. 2. Through this activity - fig. 6 - in a special way, the X harness is packed with a special bag, so that it can be sent to the last module of the technological flow, module no. 3
Fig. 6. Performing the wrapping operation
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The first operation of the third module is palletting (3.1). This operation involves the packing of a fixed number of finished X wiring into a repack, which is a large box of wood. Finally, the last operation in Module 3 and the technology flow is delivery. This operation is to load the repositions ordered by the customer and move them to the client.
INITIAL RESULTS OBTAINED IN THE TECHNOLOGICAL FLOW ANALYSIS FOR FINITE PRODUCT CABLAGE X For the case of the studied X harness, following this technological flow, the following data are finally obtained – table 2.
Table 2. Obtained results Nr. crt. Indicator UM Values 1 Nr. X products ordered and made / day [piece/day] 1.236 2 Time worked [min] 450 3 Product cost / worker [euro/worker] 550
PERSPECTIVES OF RESEARCH In the next scientific work of this series of 3 papers, based on the results determined by the analysis of the passage of this technological flow, it is proposed to continue to achieve the following objectives: will analyze the workstations within the MB module; the production times within the MB module line will be determined; will analyze the jobs in the ZSB final assembly section; the production times within the final assembly line ZSB will be determined.
REFERENCES [1] Mitonneau, H., O nouă orientare în managementul calităţii, Editura Tehnică, Bucureşti, p. 49-51, 2009. [2] N. Belu, N., Misztal, A., Ionescu, L., M., Quality Assurance Matrix as the advanced generation of quality control, Proceedings of the 2016 International Conference on Economics and Management Innovations (ICEMI July 9-10, 2016 in Wuhan, China), Book Series ACSR – Advances in Computer Science Research, pag. 251-256, 2016. [3] Petrovan, A., Lobontiu, G., Ravai-Nagy S., Broadening the Use of Product Development Ontology for One-off Products, Applied Mechanics and Materials, Trans Tech Publications, Switzerland, 2013. [4] Roşu, M., Doicin, C., Sokovic, M., Kopac, J., Quality and Cost in Production Management Process, Journal of Mechanical Engineering, no. 54, ISSN: 0039-2480, 2008. [5] Anghel, D.,C., Belu, N., Rachieru, N., How to redesign ergonomic workstations, using neural networks and the Rula method in CATIA V5, Advanced Materials Research Vol. 1036, pp 995-1000. Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.1036.995, 2014.
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EVALUATION OF GEOMETRICAL COMPLEXITY OF PRODUCTS BASED ON THE ANALYSIS OF TRIANGULATED MODELS
Associate Prof. PhD. Yaroslav GARASHCHENKO Nat. Tech. Univ. «Kharkov Polytech. Inst.», [email protected] Kharkov, Ukraine
Abstract: The results of study evaluation possibilities of geometric complexity of industrial products are presented in this article by analyzing of functional dependence of number of triangular faces on triangulation parameters. As the main parameter of the triangulation was considered maximum size of edges. The dependence study was carried out for basic geometric bodies, which revealed the general regression equation. Test of the regression equation on models of industrial products has confirmed put forward a scientific hypothesis on the evaluation possibility of geometric complexity of industrial products based on the analysis of this functional dependence.
Keywords: Additive manufacturing; DFAM; triangulated model; geometric complexity of product.
1. INTRODUCTION At the present time there is a need to develop a scientifically sound methodology for determination of manufacturability and choice of strategy for manufacturing of product on the basis of 3D model analysis [1]. Some authors [1, 2] determined by manufacturability indexes based on CAD-models of products without evaluating the level of its complexity. But the practice shows a significant role of product complexity to design for additive manufacturing (DFAM) [3] and select effective strategies for making, which includes rational build orientation, build step (variable or constant), slicing strategy and product decomposition for packing on build platform [4]. With respect to additive manufacturing basic geometric information for production is a triangulated model of industrial product [5]. The triangulated model unifies the representation of the product surface, which creates prerequisites for the analysis of faces system. Analysis of the 3D model has to represent the definition of dimensionless characteristics to measure the geometric complexity of product and to predict workability of its manufacture [2, 6]. In known works, the evaluation of geometric complexity of products, prepared for additive manufacturing, produced on the basis of parameters determined by topological and morphometric analysis of CAD or triangulated models [1, 7-10]. The obtained characteristics did not take into account features of CAD-system for setting parameters of triangulation. Their values set constraints when solving the optimization of transition to triangulated model. The parameters of triangulation, given product design, determine the number and geometric (statistical) characteristics of triangular faces. Therefore, the existing characteristics are not sufficiently representative for the subsequent adoption of technological solutions during the preparation phase to additive manufacturing.
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In this article, scientific hypothesis that analysis of triangulation parameters influences on number of triangular faces can be used to determine geometric complexity of products and, consequently, workability of their production with additive manufacturing. The purpose of article is to consider estimation of geometrical complexity of individual products on the basis of analysis of triangular faces number dependence from triangulation parameter (maximum allowable size of edges).
2. STATEMENT OF BASIC MATERIAL The study used Autodesk PowerShape CAD-system offering enough flexible settings of triangulation [11]. In PowerShape is provided to set two of parameters defining the triangulation of model surfaces: allowable error Δmax and maximum allowable size of edges lmax. The main parameter is Δmax, that given complexity of surface geometry (surface type and its bounding contours) determines number of triangular faces. An additional parameter lmax sets the limit on maximum edges size of triangular faces that in some cases (especially for flat surfaces) increases number of faces when triangulation. The feature of parameter lmax in "boundary" effect on sites of a surface close to contours, which leads with regard to their complexity additional increase in the number of faces. Settings in Autodesk PowerShape allow to set the value of Δmax is large enough, as a result of lmax becomes main parameter that specifies the limitations when triangulation. Therefore, lmax is of special interest to the analysis of functional dependence of triangular faces number Nface from triangulation parameters. Functional regression analysis of the dependence Nface = f(lmax) were performed in a professional statistical package of StatSoft Statistica and MS Excel. Analysis of Nface = f(lmax) for a set of simple geometric shapes and several test models of industrial products (shown in Fig. 1) will identify characteristics to measure the geometric complexity of the model. Absolute numbers of triangular faces for the studied models differ significantly, therefore, to provide a comparative analysis of the results and their joint assessment was carried out normalization of Nface and lmax [12, 13]. The transition from absolute values of Nface and lmax to relative was performed by comparison with a reference value [12]. The values of characteristics of most accurate model (with smallest lmax) of studied series of triangulated models were taken as a reference. Such a model (the most accurate) is called the base. As result of studied characteristics of triangulated models obtained on the basis of triangulation of original CAD-model and, accordingly, have model similarity, are relative to the relevant characteristic values of the basic model. Therefore, regression analysis was carried out for normalized values:
xl l max0 l max , yN N face N face0 , (1) where lmax0, Nface0 — study characteristics of the basic model (reference values).
The proposed normalization (1) allows to obtain the following value ranges x, 01 and y,N 01 for whole range of triangulation models derived from the original CAD- model.
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The analysis of yNl f() x was performed for models obtained with triangulation of the CAD-model at maximum allowable size of edges lmax = 0.2÷4 mm. The range of values lmax determined the required accuracy of triangulated model for existing equipment of additive manufacturing and a large enough interval that allows to identify the features of yNl f() x for the test models.
The study of yNl f() x for the test models are executed when sample size n = 5 (number of models obtained by triangulation of test CAD-model). Critical value of correlation coefficient was Rcr = 0.991 for number of freedom degrees df = (r ‒ 2) = 3 at significance level α = 0.001 [14]. a) b)
c) d)
e) f)
Fig. 1. 3D Models of industrial products for the regression analysis: a) shaft with keyways; b) gearwheel; с) driveshaft; d) panel; e) cover; f) fan
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By results of the regression analysis of yNl f() x based on using a set of equations from [14] and their combinations, the following regression equation with one coefficient provides the smallest values of maximum relative deviation from model data: a yxNl , (2) where a – the coefficient of the regression equation. The results of the regression analysis with equation (2) are presented in table. 1. Fig. 2 shows the curve graphics for investigated 3D-models. For simple surfaces, no significant differences between the curves is not observed, but there is decreasing trend of exponent a (coefficient of the equation (2)) with increase of contour perimeter. Models with combination of surfaces have a relatively smaller a. Increasing the number of surfaces in the model leads to
decrease in a.
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Relative maximum allowable size of edges lmax0/lmax Fig. 2. Influence of relative maximum allowable size of edges on relative number of faces of the triangulated
model (for basic model lmax0, Nface0 in table 1)
With significantly small sizes of edges of triangular faces relative to the size of 3D model, as shown by the model data (table 1), there is a quadratic dependence for yNl f() x (coefficient a = 2 in equation (2)). With the increase in edge size increases the deviation of exponent of equation (2) from value of a = 2, which is partly explained by the peculiarities of triangulation close to surface contours. Such deviation is more evident with increase of perimeter of surface contours of the model. Models with curvilinear contours than with straight-line contours at the same parameter of triangulation lmax have a larger number of triangular faces. Therefore, the
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coefficient a of equation (2) can characterize the degree of model complexity, as value of a depends on perimeter and curved contours of surfaces. Modeling results (table 1) showed a significant effect of parameter of the basic model on the exponent a, so lmax0 needs to be constant to compare CAD-models. Investigated dependencies yNl f() x for lmax0 0., 8 2 provide minimal deviation from model data. For adequate evaluation of geometric complexity of test products is shown in Fig. 1, results of analysis of yNl f() x dependence, lmax0 chosen the minimum value of rational range — 0.8 mm. Evaluation results of geometric complexity of test models of industrial products on basis of the regression analysis are presented in table 2. The obtained a coefficients (table 2) allow to quantify the geometrical complexity of product. Among comparable the models (shown in Fig. 2), largest value of the coefficient obtained for the shaft, as for the most simple of test products. Fan model has least value of the coefficient, respectively, that specifies how the part having relatively complex geometry. Visual evaluation of geometric complexity of products confirms the results of the analysis (table 2).
Таble 1. The results of regression analysis between number of triangular faces Nface and maximum allowable size of edges lmax 3D-model (dimensions, mm) Basic model Coefficient of
lmax0, мм Nface0 equation (2) Cube (L = 100) 0.8 380 424 1.952 Cube with chamfers (L = 100, с = 5) 0.8 366 809 1.927 Сube with rounded edges (L = 100, r = 5) 0.8 379 653 1.957 Cylinder (R = 50, H = 100) 0.8 298 556 1.961 Cylinder with chamfers (R = 50, H = 100, с = 5) 0.8 281 512 1.961 Cylinder with rounded edges (R = 50, H = 100, r = 5) 0.8 283 072 1.939 Cone (R = 50, H = 100) 0.8 205 938 1,979 Sphere (R = 50) 0.8 217 722 2.001 Sphere (R = 100) 0.8 872 460 1.999 Sphere with a hole (R = 100, r = 15) 0.8 1 493 549 1.974 Sphere with a hole (R = 100, r = 25) 0.8 1 551 541 1.971 Sphere with two holes (R = 100, r = 25) 0.8 1 720 679 1.962 Torus (R = 50, r = 5) 0.8 75 264 1.942 Torus (R = 50, r = 10) 0.8 156 480 1.959 Helicoid (R = 50, H = 100) 0.8 258 338 1.906 Spring (R = 50, r = 5, H = 100) 0.8 362 232 1.939
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Table 2. The results of regression analysis between number of triangular faces Nface and maximum allowable size of edges lmax for test models of products Test models of products Number of triangular faces of basic Coefficient of (dimensions, mm) model (lmax0 = 0.8 mm), Nface0 equation (2) 1. Shaft (60.0 x 60.0 x 216.5) 252 360 1.868 2. Gearwheel (85.8 x 85.8 x 60.0) 321 468 1.844 3. Driveshaft (147.5 х 50.0 х 124.0) 330 292 1.822 4. Panel (151.5 x 195.5 x 20.1) 575 914 1.699 5. Cover (83,9 х 101,3 х 43,2) 237 362 1.610 6. Fan (92,0 х 92,0 х 26,0) 251 400 1.577
Presented in table 2, the values of coefficient of equation (2) allow a relative assessment of geometric complexity of product. This possibility is of interest for DFAM. To determine index of geometric complexity of products it is necessary to further study the effect of parameters of triangulation on number and geometric (statistical) characteristics of faces of triangulated models for various types of surfaces, used in mechanical engineering.
3. CONCLUSIONS 1. Analysis of the impact of triangulation parameter (the maximum allowable size of edges lmax) on number of faces of triangulated model allows to estimate the geometric complexity of products, and eventually — the manufacturability of their production with additive technologies. 2. The transition from absolute values of studied characteristics to relative by comparison with reference values provides the opportunity for joint evaluation of research results, regardless of geometric complexity of model. The values of characteristics of most accurate model (with least value of lmax) of studied series of triangulated models are taken as references.
REFERENCES [1] Gupta, S. K., D. Das, W. C. Regli, and D. S. Nau, 1997. Automated manufacturability analysis: A survey, Research in Engineering Design, 9(3), pp. 168-190. [2] Gupta S. K., and S. N. Dana, 1995. Systematic approach to analyzing the manufacturability of machined parts, Computer-Aided Design, Volume 27: pp. 323–342. [3] Zhang, Y. et al., 2014. Evaluating the design for additive manufacturing: a process planning perspective. Procedia CIRP, 21, 144–150. [4] Kumke, M., H. Watschke, and T. Vietor, 2016. A new methodological framework for design for additive manufacturing. Virtual And Physical Prototyping, Vol. 11, Iss. 1, pp. 3-19. [5] Gibson, I., D. W. Rosen, B. Stucker, 2010. Additive Manufacturing Technology: Rapid Prototyping to Direct Digital Manufacturing. Springer Verlag, New York, 459 p. [6] ElMaraghy, W., H. ElMaraghy, T. Tomiyama, and L. Monostori, 2012. Complexity in engineering design and manufacturing, CIRP Annals: Manufacturing Technology, 61, pp. 793–814.
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[7] Belaziz, M., A. Bouras, and J. M. Brun, 2000. Morphological analysis for product design, Computer-Aided Design, Vol. 32, Iss. 5–6, pp. 377-388. [8] Grabchenko, A. I., V. L. Dobroskok, Y. N. Garashchenko, and L. N. Abdurajimov, 2013. Integral Characteristics of Triangulation 3D Models of Products, Key Engineering Materials, Vol. 581, pp. 281-286. [9] Kerbrat O., P. Mognol, and J.-Y. Hascoet, 2010. Manufacturing complexity evaluation at the design stage for both machining and layered manufacturing. CIRP Journal of Manufacturing Science and Technology, Vol. 2, Iss. 3, pp. 208-215. [10] Gadh, R., and F. B. Prinz, 1992. Recognition of geometric forms using the differential depth filter. Computer Aided Design, Vol. 24, Iss. 11, pp. 583-698. [11] Dobroskok, V. L., Y. N. Garashchenko, S. I. Chernyshov, and N. V. Zubkova, 2010. The possibilities of modern CAD systems in the transition to triangulated models. High technologies in mechanical engineering, Nat. Tech. Univ. "Kharkov Polytech. Inst.", Vol. 1(20), pp.79-86. – In Russian. [12] Dodge Y., 2003. The Oxford Dictionary of Statistical Terms, Oxford University Press, 512 p. [13] Bureeva, N. N., 2007. Multivariate statistical analysis using APP "STATISTICA". Teaching material for the training program "The use of software in research and teaching of mathematics and mechanics". Nizhny Novgorod, 112 p. – In Russian. [14] Kolker, Ya. D., 1976. Mathematical analysis of machining accuracy. Кiev, Tehnika, 200 p. – In Russian.
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ABOUT FEATURES OF SIMULATION MODULE IN SOLIDWORKS
prof.PhD.eng. Cătălin IANCU Engineering and Sustainable Development Faculty,‖C-tin Brâncuşi‖ Univ. of Tg-Jiu, [email protected]
Abstract: In this paper are presented the additional features and analysis steps of Simulation module in SolidWorks, for conducting a more detailed study of designed parts. There are presented the module features, the settings that have to be done for such analysis and the results shown after analysis.
Keywords: SolidWorks, Simulation, FEM analysis.
1. INTRODUCTION
As presented in [1], SolidWorks SimulationExpress Module ―offers an easy-to-use first pass stress analysis tool for SolidWorks users. SimulationXpress can help you reduce cost and time-to-market by testing your designs on the computer instead of expensive and time-consuming field tests‖. As described in [2], without using a simulation tool, the design process is a time-consuming product development cycles. Typically must be taken following steps: build the model in SolidWorks CAD system, prototype the design, test the prototype in the field, evaluate the results of the field tests and modify the design based on the field test results. This process can continue until a satisfactory solution is reached. By using SimulationExpress/Simulation the same task can be accomplish, reducing costs, by testing the model using the computer rather than field tests, reducing time to market by reducing the number of product development cycles and optimize the designs by simulating concepts and scenarios before making final decisions [2]. Two modules are available for SolidWorks: SimulationXpress that handles part documents (only solid bodies), included in the core software, and Simulation that handles parts and assemblies too, which is available as a separate product, including configuration support and expanded options. SolidWorks Simulation is a design analysis system fully integrated with SolidWorks. SolidWorks Simulation ―provides simulation solutions for linear and nonlinear static, frequency, buckling, thermal, fatigue, pressure vessel, drop test, linear and nonlinear dynamic, and optimization analyses‖ [1].
Fig. 1. Generic steps on Simulation: Design → Mesh → Analysis and Results [1]
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To begin Simulation, open a part, load Simulation Add-In and click Simulation tab (Command Manager tabs) or menu Simulation.
Fig.2. Simulation tab or Simulation menu
There is a wizard interface of Simulation that guides through a step-by-step process to specify Study type, Material, Fixtures and loads, Mesh and Run the simulation, and view the Results.
2. SIMULATION TASK PANE (SIMULATION ADVISOR)
When you have a part open, the Simulation Task Pane appears in the right side of working board to let you begin the step-by-step process of analysis.
2.1. Study In this step it‘s chosen the type of study: linear and nonlinear static, frequency, buckling, thermal, fatigue, pressure vessel, drop test, linear and nonlinear dynamic, and optimization. In this example was chosen the linear static analysis.
2.2. Material In this step it is assigned material properties to the part, by choosing one material from library or by defining individual properties. This step is not required if material properties were defined previously in the CAD system.
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Fig. 3. Choosing material for the part
2.3. Interactions In this step it‘s applied fixtures to faces or edges of the part, as shown in figure 4, and loads like forces or pressures, or both to faces of the part.
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Fig.4. Fixtures and pressure (load) applied to part
2.4. Mesh In this step it is generated the mesh of finite elements for FEA. The program automatically creates a shell mesh for surfaces and sheet metals with uniform thicknesses. The structural elements are meshed with beam elements and solid bodies are meshed with solid elements. A mixed mesh is created when different geometries (solid, shell, structural elements, etc.) exist in the model. For the type of finite element and mesh density can be used changed settings, as described in [3], as shown in figure 5 – left pane.
Fig. 5. Mesh parameters
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2.5. Run Uses the default settings or changed settings for the simulation and then run analysis. Practically it‘s done a static analysis by FEM of studied part, with default or changed settings.
2.6. Results After the running analysis it can be displayed simulation results as: - Animation of the part as it stretches under the load and deformed shape of the model (figure 6);
Fig. 6. Animation and deformed shape of model
If the model doesn‘t deform as expected, the analysis can be start over with the very first step of simulation for various modification. - VonMises stress distribution in the model with or without annotation for the maximum and minimum stress values (figure 7);
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Fig. 7. Stress distribution- Displacement distribution in the model with or without annotation for the maximum and minimum displacement values (figure 8);
Fig. 8. Displacement distribution - Factor of safety (FOS) distribution (fig.9).
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Fig. 9. Safety factor distribution 4. CONCLUSIONS
After running the analysis of the designed part, the results are as follows: - The allowed yield strenght value for material (plain carbon steel) is 2.2*108 N/m2. - The software automatically adds the load of gravity of 9.81 m/s2 (the red arrow in the middle of the model). - The maximum VonMises stress in the designed part is, at these dimensions, according to analysis results, 1.229*105 N/m2, value significant lower than the limit. - The maximum displacement is, at these dimensions, according to analysis results, 3.345*10-5 m. - The safety factor distribution can be displayed as an absolute value or related to VonMises stress, that cannot be overcome (FOS < 1). In conclusion, by following the steps and the settings described in this paper, as stated in [4], one can perform a detailed study using Simulation module, that can lead to reducing the number of product development cycles and then reducing TTM (time to market). Further can be optimized the design and thus reducing cost by testing the model on the computer, rather than field tests. For extended study it must be used SolidWorks Simulation that can handles parts and assemblies also. Although is available only as a separate product, it includes configuration support and expanded options. Some of these options are: - Can be performed an optimization analysis on an assembly. 197 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
- Can be specified up to 20 dimensions as design variables. - Can be specified up to 60 criteria for the model to satisfy. - Can maximize or minimize any quantity that can be defined as a sensor. It is obvious that is very useful, both in terms of time and money saving, leading indirectly to better sustainability of designed products.
REFERENCES
[1]. SolidWorks user help, Dassault Systèmes SolidWorks Corporation, Waltham, MA, USA, 2014. [2]. Iancu, C., About SimulationExpress module features, Fiability & Durability Revue, ISSN 1844-640X, 1/2015 [3]. Iancu, C., Dimensional optimization of mechanical press, Ed. MJM, Craiova, Romania, 2002. [4]. Lombard, M., SolidWorks Bible, Wiley & Sons, USA, 2013
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ABOUT OPTIMIZATION DESIGN STUDY ON SOLIDWORKS
prof.PhD.eng. Cătălin IANCU Engineering and Sustainable Development Faculty,‖C-tin Brâncuşi‖ Univ. of Tg-Jiu, [email protected]
Abstract: In this paper are presented the steps to be taken in SolidWorks for conducting an optimization design study of parts designed. There are presented the Design Study module features and the settings that have to be done for such analysis and the results and their interpretations.
Keywords: SolidWorks, Design Study, optimization.
1. INTRODUCTION
As stated in [1], along with other modules of SolidWorks, like SimulationExpress or Simulation, Design Study, an extended version of a feature of SimulationExpress, one can ―help you reduce cost and time-to-market by testing your designs on the computer instead of expensive and time-consuming field tests‖. Without using an optimization study, the best part design can be achieved only by expensive and time-consuming product development cycles. So typically must first build the model in SolidWorks CAD system, prototype the design, test the prototype in the field, evaluate the results of the field tests and modify the design based on the field test results. This process can continue until a satisfactory solution is reached. On the other hand by using SolidWorks modules for preliminary studies (SolidWorks SimulationXpress/Simulation/ Design Study) it can be accomplished tasks like testing the model using the computer rather than field tests, thus reducing cost, reducing time to market by reducing the number of product development cycles and optimize the designs by simulating concepts and scenarios before making final decisions [2]. Design Study is one feature of SolidWorks that can be used for achieving mentioned goals above. There are two main modes for running a Design Study: - Evaluation, when it‘s specified discrete values for each variable and use sensors as constraints. The software runs the study using various combinations of the values and reports the output for each combination. - Optimization, when it‘s used values for each variable, either as discrete values or as a range. Sensors can be used as constraints and as goals. The software runs iterations of the values and reports the optimum combination of values to meet a specified goal (minimum mass for example). To begin a Design Study do one of the following: Click Design Study (Tools toolbar) or Insert menu> Design Study > Add. A new design study can be done by right-click an existing Design Study tab and click Create New Design Study. A Design Study tab appears at the bottom of the graphics area (figure 1).
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Fig. 1. Starting a design study
2. DESIGN STUDY TASK PANE
The wizard interface of Design Study guide through a step-by-step process to specify Variables, Constraints and Goals, run the study, and view the results (figure 2).
Fig. 2. Design study task pane
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For Evaluation studies only, clear Optimization and for Optimization studies, select Optimization. This option allows optimization of a model dimension based on a specified criterion and constraint. Practically it‘s done a dimensional optimization rather than a shape one, using as goal (objective function) for example minimization of mass [3]. As constraint for example, it can be find the optimal dimensions of a part such that the Von Mises stresses do not exceed a specified value. To perform optimization analysis must be taken the steps: - In the graphics area, select a model dimension (design variable) to optimize. The model dimension appears in the Add Parameters dialog box. It can be defined several parameters to be used as design variables, as shown in figure 3. - Click OK. - In the Design study pane, under Variables, enter the Min value, which is the minimum allowable value for the dimension, and the Max value, which is the maximum allowable value for the dimension. When specifying these values, they must not contradict other relations specified in the model.
Fig. 3. Defining parameters for optimization
- Under Constraints: select the criterion from the list: -Factor of Safety - Max Displacement - Max Stress 201 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
As a constraint was chosen the Max Stress and was set a 10 time less than the yield limit, meaning 2.107 N/m2. - Under Goals: select from a list. As goals can be selected sensors as: -Mass Properties - properties such as Mass, Volume, Surface Area, and Center of Mass. -Dimension - monitors selected dimensions. -Simulation Data – can be selected simulation results such as stress, strain, and displacement. As goal was selected the minimization of mass, as shown in figure 4. It can be seen that for chosen variables and the increasing steps, there are possible 210 active scenarios.
Fig.4. Variables, constraint and goals for optimization study
Since there are a large number of possible scenarios, the software warns about time consuming analysis and suggests changing option to Fast, and after a preliminary analysis can be done a more detailed study only for selected scenarios (figure 5).
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Fig.5. Options for Design Study quality
3. RUNNING STUDY AND RESULTS
3.1 Run After clicking Run there are performed a minimum number of iterations. The results appear in Results View (figure 6), and the model updates to reflect the optimal value.
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Fig. 6. Results view of optimization design study
As a design variable was defined: - the diameter of the three holes, which is 25 mm, and Min value was set to 20 mm and the Max value was set to 30 mm, with a step of 2 mm. - the upper width of the part, which is 15 mm, and Min value was set to 10 mm and the Max value was set to 18 mm, with a step of 2 mm. - the high of milled part, which is 100 mm, and Min value was set to 80 mm and the Max value was set to 110 mm, with a step of 5 mm. As a constraint was defined the VonMises stress and the value was set a 10 time less than the yield limit for material (plain carbon steel) meaning 2.107 N/m2 As specified before as goal (objective function) was selected the minimization of mass. After specifying option Fast for design study where done only 15 steps from the initial possible 210 active scenarios.
3.2 Results The maximum VonMises stress in the designed part is, at final proposed dimensions, according to analysis results, is 2.046.105 N/m2. After running the optimize step of the analysis, the results are as follows (figure 6): - the diameter of the hole: - before: 25 mm - after: 30 mm 204 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
- the upper width of the part: - before: 15 mm - after: 10 mm - the high of milled part: - before: 100 mm - after: 110 mm -the maximum VonMises stress: - before: 2.046.105 N/m2 - after: 2.089.105 N/m2 - the mass of designed part: - before: 2.734 kg - after: 1.939 kg
4. CONCLUSIONS
So at this stage of the design study can be achieved a mass reduction of approx. 29%. The analysis can be continued by adding another dimension of the model to the study, until it can be obtained a significant mass reduction, with respect to specified constraints. The study can be extended by using several options. Some of these options are: - Perform optimization analysis on an assembly (for optimization background and options can be checked [4]). - Specify up to 20 dimensions as design variables. - Specify up to 60 criteria for the model to satisfy. - Maximize or minimize any quantity that can be defined as a sensor. In conclusion, as presented in [5], by following the steps and the settings described in this paper, one can perform a Design Study that can lead to: - reducing time to market by reducing the number of product development cycles; - optimize the design; - reducing costs by testing the model on the computer, rather than field tests. By using the Design Study feature of SolidWorks one can save time and money, and create better products.
REFERENCES
[1]. SolidWorks user help, Dassault Systèmes SolidWorks Corporation, Waltham, MA, USA, 2014. [2]. Iancu, C., About SimulationExpress module features, Fiability & Durability Revue, ISSN 1844-640X, 1/2015. [3]. Iancu, C., Dimensional optimization of mechanical press, Ed. MJM, Craiova, Romania, 2002. [4]. Iancu, C., Contributions to dimensional optimization of mechanical press in dynamic regime, Ph.D. Thesis, University of Pitesti, Romania, 2002. [5]. Lombard, M., Solid Works Bible, Wiley, USA, 2013.
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THE DETERMINATION AND APPRECIATION OF PROFESSIONAL MICROCLIMATE AT A WORKPLACE
Oana CHIVU, , Claudiu BABIS, Andrei DIMITRESCU, Dan Florin NIŢOI Univ. Politehnica of Bucharest, [email protected]
ABSTRACT:The microclimate at work is a very important element that puts a mark on worker health. The paper presents the methodology for determining and appreciating the professional microclimate through its components: air temperature; Relative air humidity; Airflow velocity; Caloric radiation; The working surface temperature at work. The aim of the paper is to educate in order to obtain an appropriate microclimate to avoid overworking of the visual analyzer, stimulate higher nerve activity processes, increase working capacity, prevent occupational diseases, work accidents and chronic fatigue. Keywords: microclimate, temperature, humidity, air currents
Introduction
By microclimate we understand all the physical factors of the air from a bounded space (workplace), which exerts its action on the thermoregulation function. The microclimate components [1], [2], [3] are normalized in relation to heat release in the human body due to physical effort. The constituent factors of the professional microclimate are the following: air temperature (measured in degrees Celsius ° C); Relative humidity (expressed in percentage); Air velocity (measured in m / s); Calorific radiation (measured in horsepower / cm2 / min); And the working surface temperature (measured in ° C). The temperature [4] is determined with the following devices: globtermometers, Assman psychometers, digital psychometers and thermographs. With globtermometer, the temperature is expressed in degrees Celsius. The Assmann Psychrometer is an apparatus that consists of two identical mercury thermometers. The two metal tubes join in a central tube at the upper end of which a vacuum cleaner is installed. One of the thermometer tanks is covered with a cotton sleeve that moistens with a pipette. Thus, Assmann's psychrometer has a dry bulb thermometer and another with a wet reservoir. The Assmann psychrometer can also be used in the absence of globtermometer. The dry tank thermometer indicates the air temperature. Reading is done after 5-6 minutes, determining first the wet thermometer, then the whole degree. The dry bulb thermometer is also read. The wet tank thermometer, due to the heat lost by evaporating the water on the cloth covering the wet bulb, depending on the air saturation deficit for that temperature, indicates a lower temperature than the dry tank thermometer. The apparatus shall be kept suspended during the suspension, vertically, on a rod holder at the place where it is to be determined. The digital psychrometer now replaces Assmann's psychrometer and determines dry temperature and relative humidity directly. With the help of thermographs, continuous temperature recording can be made for 24 hours or more. The temperature of working surfaces or varied surfaces is measured with adaptive thermometer (flat bulb).
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To measure the humidity in the working atmospherethere are used: Assman psychometers, hydrographers to record humidity continuously for 24 hours or more and digital psychometers. Air velocity is determined using anemometers and catatometer meters as devices. Anemometer with blades or cups is used for speeds above 0.1 m / sec. The airflow speed in m / s or m / min is read directly on the dial. Anemometers can also be digital. The Hill Catameter is an alcohol thermometer made up of two tanks, one larger at the bottom and one smaller at the top, joined by a capillary tube. The capillary tube has two divisions: 350C and 380C. Cooling heat loss from 380 ° C to 350 ° C is always the same and specific to each appliance, which is the catafactor, denoted F (eg F = 493). Note the time at which the alcohol column drops from 380C to 350C in seconds ("t"). The calculation formula is used to determine the velocity of the air currents. "Air cooling power" and "air heating power" are measured as the temperature is below 350 ° C or above 380 ° C, with the time required for the alcohol in the capillary tube (alcoholic meniscus) of the cataterometer to drop from 380 ° C to 350 ° C , Respectively, to rise from 350C to 380C. At each point studied three measurements are made and their arithmetic mean is used. Caloric radiations are determined with the globtermometer. It consists of a mercury thermometer whose tank is centered inside a metal sphere, with a matt black surface. The wall thickness of the sphere is 0.1-0.2 mm, the diameter of the sphere varies between 10 cm and 15 cm, and the metals used are copper and aluminum.
Description of the appliance
For the assessment of microclimate, you can use the Casella Anemometer M12900X, which measures both the airflow speed and the temperature, humidity or pressure according to the exact model. This appliance is ideal for on-site measurements of air exhausts due to the small size of the anemoscope (30 mm). It can also be used for more general wind and wind current measurements as specified. The M12900X anemometer is shown in Figure 1.
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Fig.1 Anemometer of the range M12900X for Casella
The anemometer shown in Figure 2.1 consists of the following elements: 1-button HOLD and RECALL; 2-button ESC (Escape) and REC (Record); 3-button MAX, MIN and AVG (Average = Average); 4-button automatic closing and arrow "up"; 5-button ENTER and change unit; 6-button Power and arrow "down"; 7-button SET and background light; 8- display (display) and background light; 9-pin sensor connector to the device; 10-cell compartment; 11-cell battery cover; 12-probe connector; 13-handle probe; 14-sensor sensor (temperature / humidity); 15-propeller; 16-pressure internal sensor (M129003 only). The characteristics of the poster are shown in Figure 2.
Fig. 2 Characteristics of the poster
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The component parts of the poster are: 1 main display; 2-sided display; 3-zone display symbol in operation; 4-battery indicator discharged; 5-symbol auto lock indicator; 6 main units displayed; 7 secondary units displayed. The general device specifications are shown in Table 1
Table 1 General device specifications
Display (display) 42 mm (W)*33 mm (L) monochrome LCD with backlight
Maximum operating 25 mA current Battery Type 1 piece type - PP3 (6F22 zinc carbon) Lifetime battery Aprox. 100 ore Apparatus: 130 (L)*56 (W)*38 (H) mm Dimensions Sonde: 195 (L)*47 (W)*30 (H) mm Cable length about 1 meter Weight Apparatus: aprox. 160 g Sonde: aprox. 100 g
Accessory User Manual, Carrying Case, 9V battery,
probe Operating conditions Temperature: 5°C ~ 40°C Humidity: 0% ~ 80% RH Temperature: -10°C ~ 60°C Terms of use storage Humidity: 0% ~ 70% RH
The speed variation range is shown in Table 2.
Table 2 Range of speed variation
Humidity Field Rezolution Accuracy m/s 0,4 ~ 25 0,1 ±2% + 0,2 Km/hr (kph) 1,5 ~ 90 0,1 ±2% + 0,8 Mph 0,9 ~ 55 0,1 ±2% + 0,4 Knots (kts) 0,8 ~ 48 0,1 ±2% + 0,4 Ft/min (fpm) 79 ~ 4921 1 ±2% + 40 Beaufort 1 ~10 1 --
The range of flow variation is shown in Table 3.
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Table 3 Flow variation Humidity Field Rezolution Accuracy CMM 0 ~ 9999 1 -- CFM 0 ~ 9999 1 --
The range of temperature variation is shown in Table 4.
Table 4 Variation temperatury Humidity Field RezolutionAccuracy °C -20 ~ 60 0,1 ±1°C °F -4 ~ 140 0,1 ±1,8°F
The range of humidity variation is shown in Table 5
Tabele 5 Variation umiditatii Humidity Field RezolutionAccuracy %RH 20 ~ 80 0,1 ±3,5%RH %RH <20 ,>80 0,1 ±5%RH
Limitele de variatie ale presiunii sunt prezentate in tabelul 6. The pressure variation limits are shown in Table 6.
Tabelul 6 Variatia presiunii absolute Humidity Field RezolutionAccuracy hPa 35 ~ 1100 0,1 ±2hPa mmHg 263 ~ 825 0,1 ±1,5mmHg inHg 10,3 ~ 32 0,1 ±0,1
Experimental determinations Experimental determinations should consist of two phases: determination of determination sites and determination of determination times. The setting of the microclimate determination points should include the following: • places with the maximum degree of harm (eg in front of the oven, near steam boilers, etc.); • Jobs where most workers are grouped; • At the opening of the room (right of doors, windows);
With regard to the establishment of vertical microclimate points, it should include the following: • at 0.5 m, 1.0 m and 1.5 m in order to appreciate any differences in heating (cooling) between different parts of the workspace; - to establish the comfort microclimate (operating temperature) will be done
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determinations and at a height of 0.1 m and 1.1 m respectively, which corresponds to the ankle and cervical region of a worker working in the seated position. The determination of determination times should be based on determinations made during the day of work (start, middle, end): • in the peak periods of the technological process; • in hot and cold weather; • During and without the operation of the ventilation system
Interpretation of results
Appreciation of cold microclimate is done by using minimum thermal limits. For determining the normative values of temperature, the metabolic class (physical strain or heat release intensity) and the velocity of air currents are used as variables as shown in Table 7. . Table 7 Minimum thermal limits admitted to workplaces.
Globtermometer temperature Class of metabolism Speed of air currents (m/sec.) (°C) (W) M ≤ 117 18 ≤0,2 117 < M ≤ 234 16 ≤0,3 234 < M ≤ 360 15 ≤0,4 M ≥ 360 12 ≤0,5
The maximum thermal limits are used to appreciate warm microclimate. In order to establish the maximum allowed temperature values from hot microclimate workplaces, the metabolic class (physical strain or heat release) is used; The existence of air currents (air mobility); The worker's acclimated or unconditioned quality and the location of the workplace with or without exposure to the sun. The WBGT (wet, bulb, globe, temperature) index used to estimate the maximum thermal limit is measured or calculated with relation 1 for indoor and outdoor activities without solar exposure and with relation 2 for outdoor activities with sun exposure.
WBGT = 0,7tun + 0,3tg 1 WBGT = 0,7tun + 0,2tg + 0,1ta 2
Where ‚ta‘ is your dry air temperature, in ° C, tg is the globothermometer temperature, in ° C, and the cannon is the natural wet temperature, ° C. The calculated value of the WBGT index, according to the above formula, compares with the value in Table 8. This should not be exceeded, otherwise the risk of illness would be affected.
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Table 8 Maximum allowed thermal limits at work
Index WBGT(°C) Class of metabolism
(W) A person acclimated to heat Unaccounted person to heat Rest (0) 33 32 Reduced metabolism 30 29 (1) Medium metabolism 28 26 (2) With No move Intensive With movement No move movement Perceptible metabolism (3) Perceptible a Perceptible Perceptible a a Air 23 a air 25 Air 26 Air 22 Very metabolic 23 25 18 20 Intense (4)
Regarding comfort microclimate, the following conditions must be ensured in workplaces (offices, control rooms, video-rooms, social rooms, etc.) where the professional activity requires thermal comfort.
For the summer season: • Operating temperature between 23 - 26 ° C; • Vertical difference of air temperature values at 1.1 m and 0.1 m above ground (head and ankle) less than 3 ° C; • Relative air humidity between 30-70%; • Average air flow rate between 0.1 - 0.3 m / s. For winter: • Operating temperature between 20 - 24 ° C; • Vertical difference of air temperature values at 1.1 m and 0.1 m above ground (head and ankle) less than 3 ° C; • Relative air humidity between 30-70%; • Average air flow rate between 0.1 - 0.3 m / s; • Differences less than 10 ° C between the radiation temperature of the windows or other vertical surfaces and the radiation temperature of the objects in the room. The operative temperature (T0) is calculated with a 3:
T0= A *Ta + (1 - A)* Tr 3 where: Ta is the dry air temperature, ° C; Tr is the average radiation temperature, ° C, and A is a coefficient whose values are: 0.5 if the air current is <0.2 m / s; 0.6 if the velocity of the air flows is between 0.2-0.6 m / s and 0.7 if the velocity of the air flows is between 0.7-1 m / s. 212 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X
Concluzion
The quality of work is closely related to the characteristics of professional microclimate. Therefore, a number of prophylactic measures are required, depending on the type of microclimate. Prophylactic measures in the case of professional exposure of workers to warm microclimate (temperature at work constantly above 30 ° C) are: • At workplaces where the air temperature exceeds constantly 300C, salt water (1g NaCl / l), 2-4 l / person / exchange, distributed at 16-18oC, will be provided; • Appropriate working arrangements (hot microclimate staff will have breaks to restore the thermoregulation capability, the duration and frequency of which are set according to the intensity of the effort and the values of the microclimate components; • Wide-cut clothing made of absorbent fabrics (cotton, cotton) to allow air exchange by replacing the warm air around the human body and to absorb the sweat; • Comfort rooms with microclimate comfort.
Prophylactic measures for workers exposed to cold microclimate (constant temperature below 5 ° C): At low temperatures (below 5oC), hot tea will be provided in the amount of 0.5-1 liter / person / change; Adequate working arrangements so that part-time work capacity can be recovered during breaks; Thick clothing; Comfort rooms with microclimate comfort.
References:
[1] Benjamin Morille, Marjorie Musy, Comparison of the Impact of Three Climate Adaptation Strategies on Summer Thermal Comfort – Cases Study in Lyon, France , Procedia Environmental Sciences, Volume 38, 2017, pages 619-626; [2]Xiaoshan Yang, Lihua Zhao, Michael Bruse, Qinglin Meng, Evaluation of a microclimate model for predicting the thermal behavior of different ground surfaces, Building and Environment, volume 60, 2013, pages 93-104; [3] Marjorie Musy, Laurent Malys, Christian Inard, Assessment of Direct and Indirect Impacts of Vegetation on Building Comfort: A Comparative Study of Lawns, Green Walls and Green Roof, Procedia Environmental Sciences, volume 38, pages 603-610.2017, [4] Tae Cheol Lee, Takashi Asawa, Hidenori Kawai, Yukari Hirayama, Isamu Ohta, Multipoint measurement method for air temperature in outdoor spaces and application to microclimate and passive cooling studies for a house, Building and Environment, volume 114, 2017, pages 267-280;
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THE DETERMINATION AND APPRECIATION OF OCCUPATIONAL TOXICITY AT WORK
Oana CHIVU, , Claudiu BABIS, Andrei DIMITRESCU Univ. Politehnica of Bucharest, [email protected]
ABSTRACT: The occupational toxins are those chemicals that workers come into contact with during the exercise of the profession and which under certain conditions have harmful effects on the body. The paper aims to address the determination and assessment of occupational toxicities in a workplace with the aim of ensuring an adequate working enviro nment as well as preventing occupational diseases, accidents and chronic fatigue.
Keywords: Microclimate, temperature, humidity, air currents
Introduction
Occupational toxins are very dangerous, sometimes even endangering the lives of workers who come into contact with them. [1], [2], [3] For this purpose, warning symbols were developed as shown in Table 1, which warns of the main types of hazards, depending on the specificity of the professional toxicities they are referring to.
Table 1 The main types of hazards and warning symbols of professional toxins
Symbolization Description of the risks T+ Substances and preparations which, by inhalation, ingestion or cutaneous penetration in very small quantities, can cause death or chronic or acute affections of health; Examples: hydrogen cyanide, arsenic anhydride Very toxic T Substances and preparations which, by inhalation, ingestion or cutaneous penetration in small quantities, may cause death or chronic or acute health conditions; Examples: methanol, benzene, phenol Toxic
Substances and preparations which by inhalation, ingestion or cutaneous Xn penetration can cause death or chronic or acute health conditions; Examples: ethylene glycol, xylene
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Harmful C Substances and preparations which, in contact with living tissues, exert a destructive action on the latter; Examples: hydrochloric acid with a concentration greater than 25%, sodium hydroxide (caustic soda) with a concentration above 2%.
Corrosive Xi Non-corrosive substances and preparations which, through immediate, prolonged or repeated contact with the skin or mucous membranes, may cause an inflammatory reaction; May cause inflammation of the skin, mucous membranes, respiratory tract, allergies (sensitizing substances), eczema Examples: ammonia between 5 and 10%, hydrochloric acid between 10 and 25%, acrylates Irritating F+
Liquid chemicals and preparations having a very low boiling point and a low boiling point, as well as gaseous substances and preparations which are flammable in contact with air at ambient temperature and pressure; They can Extremely ignite under the action of an energy source (flame, spark, etc.) even at flammable temperatures below 0 ° C Examples: hydrogen, acetylene, ethyl ether
F Substances and preparations which can be heated and then ignited in contact with air at ambient temperature without energy input; Or solid substances and preparations which can easily ignite after brief contact with a source of ignition and which continue to burn or to be consumed after removal of the source; Or liquid substances and preparations with a very low flash point; Or substances and preparations which, in contact with water or wet air, emit highly flammable gases in dangerous quantities; Examples: acetone, ethyl Highly alcohol. flammable
Flammable - Liquid substances and preparations with a low flash point; May Flammable ignite under the action of an energy source (flame, spark, etc.) Examples: white-spirit.
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E Solid, liquid, pasty or gelatinous substances and preparations that can exothermally react in the absence of oxygen in the atmosphere, producing gas emissions immediately and which, under determined conditions, detonate, produce a rapid deflagration or under the effect of heat explodes when they are Partially closed; They can explode either in the presence of a Explozive flame or by knocking or rubbing. Examples: nitroglycerin.
O
Substances and preparations which in contact with other substances, especially those which are flammable, have a strong exothermic reaction; They can release oxygen, causing or burning corrosive substances. Oxidizing Examples: chlorates, nitric acid over 70%, peroxides
< Substances and preparations which, introduced into the environment, could present or present an immediate or delayed risk to one or more components of the environment; Being in the environment may present a hazard Dangerous for immediately or in time to the aquatic environment, soil, atmosphere or nature the in general Examples: lindane environment The main routes of entry of the occupational toxicities are by: inhalation, ingestion and contact. If accidentally dispersed in the environment, occupational toxicity is recommended when calling for the following measures: isolating a leak if this can be done safely; Taking environmental protection measures as well as ventilating the affected area. Exposure to gas is one of the most common situations in which workers are exposed in the industrial environment. Description of the appliance The device used, Testo 327, which is shown in Figure 1, is a portable measurement instrument for gas in apartment houses and methane or liquid fuel burning systems. The instrument is designed in accordance with BS 7967 and has the sealing test facility and CO test function. 216 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Fig.1 Portable flue gas analyzer These systems can be adjusted with testo 327 and checked within the applicable range. Warning: Testo 327 should not be used in potentially explosive atmospheres Long-term measurements or as a safety tool (alarm)! The Testo 327 with the Bluetooth option can only be used in countries where this feature is approved. The working and connecting areas of the gas analyzer measuring instrument are shown in Figure 2, as follows: 1: IR interface (327-2: IRDA) for printer connection, ON / OFF switch on / off; 2- symbols displayed • Battery capacity (: max.,: Empty); • print function: value transmission; • Control keys 3-key functions • Key functions (3x): shows the relevant display functions; • Up / Down keys: Change display screens; • screen illumination on / off; • Menu key; • Cancel key. 4- TC temperature probe connector, gas sampling probe connector, Gas outlet, main plug 5 lLateral: The condensate trap window with fill level display 6 on the back: service compartment (battery, measuring cells) 7 on the back: tool mount magnets on surfaces 217 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Fig.2 Measuring instrument The instrument requires detecting probes or sensors that are connected before entering measurement. If the detection is not done, stop the instrument, check the probe connection and then restart. Experimental determinations Experimental determinations consist of three phases: the phase of the collection of professional toxins and the phase of their analysis The Occupational Stage Phase Before you begin to determine toxics at work, the technological process must be known. On this basis the places, moments and methods of harvesting are established. The harvesting places (s) are selected taking into account the following: • at the workplace, where workers are permanently or regularly employed to perform or supervise the production process; • in close proximity to toxic generating sources; • the harvesting level is claimed at the workers' respiratory level, so about 1.5 m from the ground. 218 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X In cases where the harmful substance is represented by gases or vapors with net densities higher or lower than air, samples are taken at different levels to detect a possible concentration of the toxic at certain levels in the working room. The harvesting moments depend primarily on the continuous or discontinuous nature of the technological process: • In uniform technological processes: sampling is done at the beginning, mid and end of the working day; • In discontinuous technological processes and comprising several phases, each with different operations, samples are taken during each phase of the technological process; • harvesting must be done at least once in the hot season and once in the cold season; Samples will be taken both during the operation of the ventilation and during its malfunctioning to control the efficiency of the mechanical ventilation system. With regard to harvesting methods, there are two general methods for harvesting toxic substances from the working atmosphere: • methods of harvesting in retention devices; • methods of harvesting in closed capacities of known capacity. The principle of the harvesting method in containment devices is as follows: the air containing the toxin to be determined is aspirated in an absorbent medium, adsorbant or a filter capable of retaining it. The adsorbent medium is a liquid (water, chemical reagent), the adsorbent medium can be silicon gel, aluminum gel, coal, etc., and different filters are used as the filter media. Absorbent and adsorbent media are used to harvest toxic gases or vapors, and filter media to collect toxic, solid powders. The harvesting apparatus consists of: air suction devices (vacuum cleaners); Retaining devices: absorbing devices, funnels, alloys; devices for measuring the flow or volume of air: gas meter. The method of harvesting in closed containers of known capacity consists of introducing air into these vessels. So harvesting from the work area can be done through three processes: liquid displacement; airborne harvesting; and harvesting in vacuum vessels. Phase of the analysis of professional toxins For the analysis of professional toxicities, the following methods are used in particular: spectrophotometric methods (colorimetric, turbidimetric, fluorimetric); volumetric (titrimetric) methods; chromatographic methods - in particular gaseous chromatography; electrochemical methods (potentiometric, polarographic, etc.); methods of rapid determination of toxicities: indicative and automated. The most commonly used methods for the determination of professional toxins are methods of rapid determination. Indicative methods are based on certain chemical reagents that, in the presence of the substance sought, change color. The device used for this purpose is the Drager apparatus, which is made up of two parts, namely: hand pump and detector tube. The air is sucked through the detector tube - a glass tube filled with an absorbent substance soaked with the 219 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X respective color reagent. The color change along the column indicates the presence of toxic in the air and the length of the colored column is proportional to the concentration of the substance. Reading is in ppm (parts per million). Automatic methods use gas analyzers in which, by means of a pump, the air is sucked in and passed through a detector based, in particular, on a physical or physico-chemical principle. The device is coupled with a sound and light warning system. For the correct interpretation of laboratory data and therefore for risk assessment, the following should be observed: • the existence, functionality and efficiency of ventilation must be appreciated; • the microclimate conditions and intensity of physical effort must be known; • when there is more than one pollutant at the same time (combined, noxious); • consider their synergistic action, so their combined harm; In the rules of occupational medicine some chemicals have some indications: P can enter the body and through the skin and mucous intact; PC-toxic substances that are potentially carcinogenic; C-ones that have the marker are carcinogenic; FP - "very dangerous" substances. Interpretation of results The interpretation of the analytical data of the Toxicology Laboratory is an essential milestone for determining the degree of occupational poisoning risk in a workplace. The time weighted average concentration (CMPT) when there is only one toxic substance at work or more toxic independently effect substances is calculated with relation 1: CMPT = (C1 x t1 + C2 x t2 + C3 x t3 + ...... + Cn x tn)/(t1 + t2 + t3 + ..... + tn) 1 Where: C1, C2 ..., Cn are the average concentrations of the various specific phases of the process, expressed in mg / m3; And t1, t2 ..., tn represents the duration of the different specific phases of the technological process expressed in minutes, The occupational atmospheric concentrations of air are compared with the maximum permissible concentration or permissible peak concentration, expressed in mg / m3, as prescribed in the occupational health standards. The maximum permissible CMA concentration on work shift is the mean toxic concentration below which no symptom or sign of disease can be produced which can be accounted for by the most sensitive tests, except in the case of hypersensitivity. Exceeding CMA by CMPT is expressed in two ways: X and%. The permissible peak concentration (15 minutes) is the concentration of airborne toxicity in the workplace that should not be exceeded at any time during the workday. When more professional toxic substances are found in the workplace, the relationship 2 is used for the calculation. 220 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X CMPT1/ CMAS1 + CMPT2/ CMAS2 + … CMPTn/ CMASn 2 In which: CMPT1, CMPT2 ..., CMPTn is the air concentration determined for each substance (CMPT), and CMAS1, CMAS2 ... CMASn, is the maximum admissible concentration for each substance on the shift. This relationship should not exceed 1, overdelivery is expressed in two ways: how many times X and percentage%. The combined effect of toxic substances may be synergistic or antagonistic. The synergistic effect may be: • Addition synergy: A + B = AB; • potency synergism: A + B Conclusions For the correct interpretation of laboratory data and therefore for risk assessment: • the existence, functionality and efficiency of ventilation must be appreciated; • the microclimate conditions and intensity of physical effort must be known; • when there are more pollutants at the same time (combined, noxious, combined), their synergistic action will be taken into account, so their combined harmfulness; In the rules of occupational medicine some chemicals have certain indications: P - they can enter the body and through the intact skin and mucous membranes; PC - toxic substances that are potentially carcinogenic; C that have the marker are carcinogenic and FP - "very dangerous" References [1] O.N. Paramonova, E.P. Lysova, N.V. Yudina, Main Principles of Urban Lands of the Air Basin Ecological Monitoring Organization from Toxic Components of Residue and Exhaust Gases of Stationary Sources by the Example of the City of Rostov-on-Don, Procedia Engineering, volume 150, 2016, pages 2013-2018; [2] Amjad Ali, Di Guo, Amanullah Mahar, Ping Wang, Feng Shen, Rongghua Li, Zengqiang Zhang, Mycoremediation of Potentially Toxic Trace Elements-a Biological Tool for Soil Cleanup: A Review, Pedosphere, volume 27, Issue 2, 2017, pages 2015-222; [3] Karla R. Armenti, Craig Slatin, Ken Geiser, Primary prevention for worker health and safety: cleaner production and toxics use reduction in Massachusetts, Journal of Cleaner Production, volume 19, Issue 5, 2011, pages 488-497. 221 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X FACTOR ANALYSIS OF QUALITY CHARACTERISTICS Andrei DIMITRESCU, Claudiu BABIS, Oana CHIVU, Univ. Politehnica of Bucharest, [email protected] Abstract: Factorial analysis is a statistical technique designed to link a set of variables observed by a smaller number of latent dimensions. Factorial analysis is the method of explaining correlation relationships between two or more variables, in the case of quality, these variables being the quality characteristics of electrical equipment. The main idea on which the factorial analysis is based is that behind the quality characteristics (observable variables) there are latent variables (factors) that influence the dependent variables (output). Factors are linear combinations of the values of the quality characteristics, the coefficients of these linear combinations being called saturations or "loadings" of factors. Keywords: Quality, factorial analysis, quality indicators, Introduction The term calimete was adopted by the EOQC (European Organization for Quality) in 1971 and officiated in 1981 as "the science of quality measurement." In the Russian bibliographic references, for example, it is mentioned that the scientific discipline "calimetry", defined as the scientific theory that studies and realizes the methods of quality estimation, was developed in the former USR.S.S. By Garri Gaikovici Azgaldov, since 1968. Quality measure is the quantitative measure of the characteristics and attributes of a product. The quality measure assigns numerical values to a specific quality characteristic. Quality measures can be of different forms: physical and chemical measures, the percentage of non-compliant products. Quality level means a relative measure of quality, obtained by comparing the observed values with imposed values. Evaluating the quality level obtained from the manufacturing process of the product involves knowing its quality, by measuring, counting, etc. Quality assessment According to other authors [4], the data quality dimensions are as follows: Accessibility: The extent to which data is available or can be obtained easily and quickly Data sufficiency: The extent to which the data volume is appropriate for quality assessment Veridity: The extent to which data is considered true and credible Completeness: The extent to which data is not lacking and is sufficient for quality assessment Conclusion: The extent to which the data is represented as compact Consistency: The extent to which data is presented in the same format Ease of Handling: The extent to which data is easy to handle Lack of errors: the extent to which data is accurate and reliable Interpretability: The extent to which the data is in the appropriate languages, symbols and units and the definitions are clear 222 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Objectivity: The extent to which data are unpredictable and unbiased Relevance: The extent to which data is applicable and useful for determining quality Reputation: The extent to which data is considered reputable according to its source Security: The extent to which access to data is properly restricted to maintain their security News: The extent to which the data is updated enough to spoil quality Comprehensibility: The extent to which data is easy to understand Added Value: The extent to which data is beneficial and provides benefits from use The quality level can be expressed as: * A rating (exceptional quality, appropriate level, low level); * A quality indicator, index, or coefficient. In industry, product quality measurement is measured to measure product quality characteristics, as well as to determine indicators, indices, or quality coefficients. Product quality indicators are quantitative expressions of their characteristics and show the extent to which a particular product, during use, meets the conditions specific to its intended purpose. The product quality indicators system consists of two groups: indicators for assessing qualitative performance and indicators for assessing lack of quality. The quality characteristic of a product, process, or system is its intrinsic distinctive trait relating to a requirement. Measuring a quality feature is to obtain the numerical value by which the absolute value of that characteristic is expressed in certain measurement units. In assessing the quality of a product we distinguish between objective characteristics and subjective quality characteristics. The objective characteristics are those directly measurable characteristics of the product, while the subjective characteristics are those characteristics that can not be measured directly, but are more perceptible. Quality assessment for products with only objective characteristics Products with only objective features represent a particular case, most of them having both objective characteristics and subjective quality characteristics. For this type of product, it is possible to establish a global quality indicator, starting from the logical criteria that such an indicator has to fulfill. Logical Criteria: A) Comparability B) The calculation with discrete elements, the values of the qualitative characteristics should be used directly C) Expression of a structure D) Expression of Characteristics E) Substitutability of certain characteristics F) Indication of the favorable evolution of the characteristics By using the above criteria, the overall quality indicator for the product (i) is determined relative to the reference product (I): In this relation the notations used are the following: 223 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X K - the constant defining the technical level of the reference product (I), usually K = 1000 I - the product considered to be the reference I - the product analyzed Xij - the value of j characteristic for product i Yj - the share of the j characteristic +/- the chosen weight of the weight based on the proportionality of the j characteristic with the quality Factor Analysis / Analysis of the main component for the quality characteristics of a batch of electrical equipment The table summarizes the grades of performance for a batch of ten types of coffee makers. Integrated No Coffee Maker Tank Capacity Power Tea Maker Coffee Price Grinder 1 Bosch TAS 4012 Tassimo 1 5 3.91 5 1 4.13 2 Philips Saeco HD8323 Poemia Focus 1 1 2.09 1 1 4.32 3 Gaggia Classic 1 5 2.82 1 1 2.29 4 Philips Saeco HD8751 Intelia Focus 5 3 5 1 5 1.96 5 Bosch TAS 4013 Tassimo 1 5 3.91 5 1 4.36 6 Philips Saeco HD8743 Xsmall 5 1 3.18 1 5 2.62 7 DeLonghi EC330 1 1 2.09 1 1 3.92 8 Rohnson R 955 1 2.2 1.73 1 1 4.53 9 ZASS ZEM 05 1 1 1 1 1 5 10 BOSCH TES50129RW 5 3.8 3.91 5 5 1 The stages of factorial analysis are as follows: 1. Matrix table matrix characterization / product - obtaining the transformed matrix Z: Where E (x) represents the average of the matrix of the characteristic matrix / product, and s represents the standard deviation of the matrix of the characteristic product / product. 224 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Integrated No Coffee Maker Tank Capacity Power Tea Maker Coffee Price Grinder 1 Bosch TAS 4012 Tassimo -0.62 1.23 0.76 1.45 -0.62 0.54 2 Philips Saeco HD8323 Poemia Focus -0.62 -1.00 -0.71 -0.62 -0.62 0.68 3 Gaggia Classic -0.62 1.23 -0.12 -0.62 -0.62 -0.84 4 Philips Saeco HD8751 Intelia Focus 1.45 0.11 1.64 -0.62 1.45 -1.09 5 Bosch TAS 4013 Tassimo -0.62 1.23 0.76 1.45 -0.62 0.71 6 Philips Saeco HD8743 Xsmall 1.45 -1.00 0.17 -0.62 1.45 -0.59 7 DeLonghi EC330 -0.62 -1.00 -0.71 -0.62 -0.62 0.38 8 Rohnson R 955 -0.62 -0.33 -1.00 -0.62 -0.62 0.84 9 ZASS ZEM 05 -0.62 -1.00 -1.59 -0.62 -0.62 1.19 10 BOSCH TES50129RW 1.45 0.56 0.76 1.45 1.45 -1.81 2. Computation matrix of characteristics: Integrate Coffee Tea Characteristic Capacity Power d Coffee Price Tank Maker Grinder Rezervor cafea 1.00 -0.08 0.59 0.05 1.00 -0.80 Capacitate -0.08 1.00 0.61 0.69 -0.08 -0.29 Putere 0.59 0.61 1.00 0.53 0.59 -0.63 Preparare ceai 0.05 0.69 0.53 1.00 0.05 -0.13 Rasnita cafea integrata 1.00 -0.08 0.59 0.05 1.00 -0.80 Pret -0.80 -0.29 -0.63 -0.13 -0.80 1.00 3. Diagonalization of the correlation matrix of the characteristics and choice of factors: The matrix of factors is: 225 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X No. Characteristic F1 F2 1 Coffee Tank -0.88 0.45 2 Capacity -0.38 -0.86 3 Power -0.86 -0.34 4 Tea Maker -0.39 -0.79 5 Integrated Coffee Grinder -0.88 0.45 6 Price 0.89 -0.17 Considering that the sum of the first two own values reported for the diagonal matrix S is (λ1 + λ2) / tr (S) = 0,8815, the two chosen factors explain 88,15% of the total variance. In order to be able to calculate accurately, a specialized program for calculating the quality indexes was used through the utility value analysis method in the Octave 3.6.2 software environment: function [ ret ] = Qevalpca () ##load the names of the I/O files fid=fopen("Date.csv","r"); disp("Fisierele utilizate sunt:"); a=fgetl(fid); disp(a); b=fgetl(fid); disp(b); c=fgetl(fid); disp(c); d=fgetl(fid); disp(d); fclose(fid); ##load the matrix of fulfilling of characteristics q=csvread("GIC_in.csv"); n=rows(q); disp("Numarul de produse este:"); disp(n); m=columns(q); ##disp("Gradele de indeplinire a caracteristicilor pentru cele n produse sunt:"); ##disp(q); for j=1:m for i=1:n t(j)=sum(q(:,j))/n; k(j)=std(q(:,j)); z(i,j)=(q(i,j)-t(j))/k(j); endfor endfor disp("miu si (q-miu)/std") disp(t); disp(z); disp("matricea de corelatie este:") cor=(z'*z)/(n-1) 226 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X disp(cor) disp("diagonalizarea este:") [u,s,v]=svd(cor) y=u*sqrt(s); disp("factorii sunt:") disp(y) disp("y*y'") disp(y*y') dlmwrite("factors_out.csv",y) dlmwrite("z_out.csv",z) dlmwrite("cor_out.csv",cor) endfunction Conclusions: • Use of correlation matrix - reduction of number of features (coffee tank / integrated grout) • F1 / F2 are the main factors that account for 88.15% of the total variation • Case interpreting: the price is not the expression of the other quality characteristics, which leads to the conclusion that it is either "fashion" or "brand" or the positive quality characteristics should be reconsidered References: 1. Simon Board - Preferences and Utility: http://www.econ.ucla.edu/sboard/teaching/econ11_09/econ11_09_lecture2.pdf 2. Ralph L. Keeney si Howard Raiffa – Decisions with multiple objectives: Preferences and Value Tradeoffs 3. John S Hammond, Ralph L. Keeney si Howard Raiffa – The Hidden Traps in Decision Making, Harvard Business Review, September-October 1998 4. Emil Oanta, Ioan Odagescu, Ilie Tamas – An original software for decision making process 5. Alvin C. Rencher - Methods of Multivariate Analysis, second edition, Brigham Young University, Wiley Interscience 6. Dr. Wolfgang Langer – Explorative Faktorenanalyse: http://www.soziologie.uni- halle.de/langer/lisrel/skripten/faktxeno.pdf 7. Felix Brosius – Faktorenanalyse - International Thomson Publishing http://www.molar.unibe.ch/help/statistics/spss/26_Faktorenanalyse.pdf 8. Faktorenanalyse - http://temme.wiwi.uni- wuppertal.de/fileadmin/kappelhoff/Downloads/Vorlesung/factor.pdf 9.http://www.statoek.wiso.uni-goettingen.de/veranstaltungen/Multivariate/Daten/mvsec5.pdf 10.http://www.faes.de/Basis/Basis-Lexikon/Basis-Lexikon-Multivariate/Basis-Lexikon- Faktorenanalyse/basis-lexikon-faktorenanalyse.html 11. Faktorenanalyse - http://www.uni-kiel.de/psychologie/andres/multi07/fas.pdf 12. Peter Tryfos – Factor Analysis http://www.yorku.ca/ptryfos/f1400.pdf 227 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X METHOD OF ANALYSIS OF VALUE OF USE Andrei DIMITRESCU, Claudiu BABIS, Oana CHIVU, Univ. Politehnica of Bucharest, [email protected] Abstract: Quality assessment consists of quantifying the current performance level in accordance with performance standards. Quality assessment measures the difference between expected and actual performance to identify opportunities to improve quality. Performance standards can be set for different quality dimensions, such as quality of technical performance or quality of compliance. The differences between the products belonging to a class are given by the qualitative characteristics that describe the product's particularities. Basic features are those that play a direct role in product functionality and can be estimated at the time of purchase. The use characteristics are those that describe the behavior of the product over time. This class includes reliability, maintainability and availability. Keywords: Value analysis, quality, Introduction Quality refers to a portion of the surrounding reality called product (entity). Significant elements, called characteristics, are identified for this entity. The characteristics of a product are subclassified into typological characteristics (belonging to a product class), qualitative characteristics and insignificant characteristics (do not influence the image of an entity). Qualitative features can be of several types: basic features, process features, or usage features. To determine the qualitative characteristics, it is necessary to identify the subjects for which the product has meaning. These subjects are: the producer, the beneficiary and the company. Fig. 1. Qualitative features Reliability is the probability that the product will work for a while without damaging it. Maintainability is the probability that the product will be repaired within a specified time. Availability is the probability that the product will work at some point. 228 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X For quality assessment, if the product has both objective characteristics and subjective characteristics, it could be proposed as a method of determination - Utility value analysis (germ .: Nutzwertanalyse / engl .: Scoring model) As a starting point, it is considered that the measurement of total quality implies the summation of the qualities of the individual subjective characteristics of a product whose degree of fulfillment is determinable by questioning a population. In order to perform the utility value analysis, the subjective quality characteristics must first be established. Subsequently, each of these features is provided with a weight, depending on the importance that this subjective quality characteristic presents. Finally, the partial utilities of each feature are calculated and then, by summing up these partial utilities, the total utility of the analyzed product is obtained. Fig. 2. Representation of the utility value analysis process In the following, steps are described for the utility value analysis process. 1. Definition of subjective quality characteristics For the beginning, the subjective quality characteristics of the analyzed product must be defined. These subjective quality characteristics may be product goals, requirements, functions or properties. 2. determining the weight of each subjective quality characteristic The subjective quality characteristics do not usually have the same importance. Therefore, for each subjective quality characteristic of the analyzed product i (Cij) a percentage of PCij is claimed. For the n subjective quality characteristics of a product (i) one can write: =1 sau =100% 3. determining the degree of fulfillment of each subjective quality characteristic For each analyzed product (i) the degree of fulfillment (GICij) of each subjective quality characteristic is established. For this purpose an independent assessment of the number of subjective quality characteristics (eg 1 to 5, "1 - very poor performance" ... 5 "- very good degree of fulfillment") is used. An evaluation can also be used according to the number of subjective qualities (n), so that the product with the best performance Ci achieves the degree of fulfillment n, the product having the Ci characteristic with the second best Degree of accomplishment gets the degree of accomplishment (n-1) 4. determining the utility / partial quality of each feature By multiplying the share of the subjective quality characteristic (PCij) with the degree of fulfillment of each subjective quality characteristic (GICij) the partial quality indicator of the subjective characteristic (j) of the product (i) is obtained. Thus, the partial quality indicator Qij, has the value: 229 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 5. determining the total quality of the product by summing up the partial qualities The sum of the partial qualities corresponding to each subjective characteristic results in the total quality indicator of the product (i), Qi: Quality of data - Measuring the quality of products, processes or services requires the collection and analysis of information, expressed in terms of measurement and metrics associated with measurements. The quality of the data used in the measurement of quality is decisive. - The dimensions or characteristics on the basis of which data quality is determined are, according to some authors [5], the following: - Completeness: Every aspect of reality is represented - Relevance: Every stored information is important to get the reality picture - Reliability: Stored data is trustworthy, meaning it can be considered true information - Quantity of data: Number of stored items - Consistency: Stored data is not contradictory - Fairness: Each set of stored data is a reality - News: Data is updated over time. The update frequency is appropriate - Accuracy: Data is stored with the required precision - The ambiguity: the data have a unique meaning - Accuracy: The data relates to reality in a precise way - Objectivity: The data do not depend on people's interpretation or evaluation - Conclusion: reality is represented with minimal information - Utility: Stored information is applicable to the entity - Usability: stored information is usable Steps used in data evaluation: 1. Choosing dimensions of interest, considering that not all dimensions of the data are relevant in all situations 2. Choosing or defining questions that characterize the dimensions of interest: Each dimension has some aspects that characterize it. In a certain situation, all aspects are not important 3. Choosing or defining metrics and techniques to answer each question 4. Establish values or ranges for each metric that determine good or poor data quality 5. Define appropriate data collection forms and data collection procedures if subjective metrics were chosen 6. Collecting data using data collection forms 7. For each metric, it has to be determined whether the quality of the data is acceptable or not and the appropriate corrective measures are taken. 230 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Preferences and utility: Theoretical bases were put by John von Neumann and Oskar Morgenstern, who in 1947 presented the four axioms of rationality, which once accomplished lead to the existence of the function of utility for a particular subject. The four axioms of rationality are as follows: A) Completeness: any two states (preferably) L and M fulfill either L> M or M> L or L = M B) Transitivity: either L, M and N preference, if L Decision Theory: Decision theory provides theoretical foundation for quality determination, and many ideas and concepts can be taken from here to determine quality. The basis of the theory of decisions is the theory of games with two participants, namely the theory of games with "nature". The game of "nature" implies that one of the participants - nature - does not want the other player to lose, and nature does not aim to maximize his own profit. In this case, of games with "nature", the decisions are classified into: - decisions in certain conditions where the future conditions are known - decisions in uncertain conditions, where there is no information regarding the probabilities of realization of the states of nature - decisions in risk situations, in which case the likelihoods of realization of the states of nature are known Decisions under certainty could correspond to the situation in which quality has only measurable (objective) characteristics. Risk decisions could shape the situation in which quality presents both objective and subjective characteristics. Thus choosing a unique strategy from a set of options corresponds to the situation in which the quality of several products having objective and subjective characteristics must be ranked. Case Study: 10 brands of coffee makers were analyzed for which the following quality features were considered: Coffee Presence / Absence: Important = 5 Capacity (liters): important = 7 Power (W): Significant = 8 Possibility to prepare and tea: important = 6 Integrated Coffee Mortar: Important = 6 Price: important = 9 231 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Based on the ordering relationship between the importance of the quality characteristics considered result from the preference matrix and the weights related to the quality characteristics. These were calculated in the software environment - Octave: Presence / absence of the coffee tank; Calculated weight: 0.03 Capacity (liters); Calculated weight: 0.19 Power (W); Calculated weight: 0.25 Possibility to prepare and tea; Calculated weight: 0,11 Integrated coffee mill; Calculated weight: 0,11 Price; Calculated weight: 0.31 The table summarizes the grades of performance for a batch of ten types of coffee makers. An independent evaluation of the number of subjective quality characteristics (from 1 to 5, "1 - very poor performance" ... 5 - very good degree of accomplishment ") was used. The degree of fulfillment of the characteristics was obtained for the objective characteristics by interpolation between the minimum and maximum values of the characteristics, taking into account whether the characteristic is positive or negative. The first five characteristics were considered positive, that is, directly proportional to quality, and the last characteristic was that the price was considered negative, that is, inversely proportional to quality. Integrated Capacit Pric No Coffee Maker Tank Power Tea Maker Coffee y e Grinder 1 Bosch TAS 4012 Tassimo 1 5 3.91 5 1 4.13 2 Philips Saeco HD8323 Poemia Focus 1 1 2.09 1 1 4.32 3 Gaggia Classic 1 5 2.82 1 1 2.29 4 Philips Saeco HD8751 Intelia Focus 5 3 5 1 5 1.96 5 Bosch TAS 4013 Tassimo 1 5 3.91 5 1 4.36 6 Philips Saeco HD8743 Xsmall 5 1 3.18 1 5 2.62 7 DeLonghi EC330 1 1 2.09 1 1 3.92 8 Rohnson R 955 1 2.2 1.73 1 1 4.53 9 ZASS ZEM 05 1 1 1 1 1 5 10 BOSCH TES50129RW 5 3.8 3.91 5 5 1 In order to be able to calculate accurately, a specialized program for calculating the quality indices was used using the utility value analysis method in the environment software Octave 3.6.2: function [ ret ] = Qeval () 232 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X ##load the names of the I/O files fid=fopen("Date.csv","r"); disp("Fisierele utilizate sunt:"); a=fgetl(fid); disp(a); b=fgetl(fid); disp(b); c=fgetl(fid); disp(c); d=fgetl(fid); disp(d); fclose(fid); ##load the vector of preferences p=csvread("vectorpref_in.csv"); disp("Vectorul de preferinte este:"); disp(p); ##load the matrix of fulfilling of characteristics q=csvread("GIC_in.csv"); n=rows(q); disp("Numarul de produse este:"); disp(n); disp("Gradele de indeplinire a caracteristicilor pentru cele n produse sunt:"); disp(q); disp("Matricea de preferinta este:"); nc=columns(p); for i=1:nc for j=1:nc if (p(i)>p(j)) pref1(i,j)=2.0; elseif (p(i)==p(j)) pref1(i,j)=1.0; else pref1(i,j)=0.0; endif; endfor; endfor; disp(pref1); s=sum(pref1,2); disp("sumele liniilor matricei de preferinte sunt:");disp(s); disp("suma elementelor matricei de preferinte este:");disp(t=sum(s)); disp("ponderile sunt:");disp(s/t); disp("Indicii de calitate pentru cele n produse sunt:"); for i=1:n Q(i)=q(i,:)*(s/t); 233 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X disp(q(i,:)*(s/t)); endfor; dlmwrite("evaluare_out.csv",Q); endfunction Conclusions: Determining the total product quality indicator results by summing up the partial utilities of each product, resulting in total quality indices: Coffee Maker 1: Quality Indicator: 3.91 Coffee Maker 2: Quality Indicator: 2.29 Coffee Maker 3: Quality Indicator: 2.63 Coffee Maker 4: Quality Indicator: 3,24 Coffee Maker 5: Quality Indicator: 3.98 Coffee Maker 6: Quality Indicator: 2,60 Coffee maker 7: Quality indicator: 2.16 Coffee Maker 8: Quality Indicator: 2.49 Coffee Maker 9: Quality Indicator: 2.22 Coffee Maker 10: Quality Indicator: 3.27 The results are dependent on the chosen quality characteristics. The results are dependent on the system of preferences of the population surveyed both for determining the weights of the characteristics and for determining the degree of fulfillment of the subjective characteristics. References: 1. Sorin Ionescu si Manuela Ionescu - Spirala calitatii, Editura Electra 2008 2. Bundesministerium des Innern – Organisationshandbuch/ Qualitative Bewertungsmethoden: http://www.orghandbuch.de/nn_414926/OrganisationsHandbuch/DE/6_MethodenTechniken/ 65_Bewertungsverfahren/652_Qualitative-node.html 3. Methode Nutzwertanalyse: http://www.hs- bremen.de/internet/einrichtungen/fakultaeten/f5/abt1/forschung/labore/fertigungstehnik/ methode4-nutzwertanalyse_neu.pdf 4. Leo.L. Pipino, Yang W. Lee si Richard Y. Wang – Data Quality Assessment: http://dwquality.com/DQAssessment.pdf 5. Monica Bobrowski, Martina Marre si Daniel Yankelevich – Measuring Data Quality: www.pragmaconsultores.com/mx/actualidad/Documents/MeasuringDataQuality.pdf 6. John Neumann, Oskar Morgenstern – Theory of Games and Economic Behaviour 234 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X DETERMINING THE RAISONAL LIMITS OF THE TISMANA CAREER AND ITS MAXIMUM ECONOMIC DEPTH Lecturer.Ph.D. Nicoleta-Maria MIHUT, Constantin Brâncuşi University of Tg- Jiu,[email protected] Abstract: Determiningtherationallimits of Tismana'scareerandits maximum economic depthis a particularly important problem andneedstoberesolvedbeforetheexploitationbegins. Iftheposition of thedepositcorrespondstothat of the land surfaceandthethickness of thediscoveryissmall, the start of theworksisobvious. If, however, undertheanalogousconditions of settlingthedeposit, thethickness of thediscoveryishigh, it isnotexcluded an advantageousexploitation of thedepositby underground miningworks. Paralleltotheincrease in thethickness of thediscovery of medium andlargeinclines, the volume of therockstobeextractedandremovedincreases, whichleadsto an increase in theup-to-date exploitation. Key words: gaussian model, pollutants, mathematical relation, parameters, mathematical modeling 1.Introduction The Tismana Mining Perimeter is located in the southwestern part of the Rovinari Mining Basin, Gorj County, 30 km from the county seat of Târgu-Jiu, on the right bank of the Jiu River. The activity carried out by EMRovinari in Tismana quarry aims at extracting up to date the lignite from the deposit, used for electricity production. The excavation capacity is 7,888 mc / h, and the capacity of the dump is 15,300 mc / h. To ensure the parameters Operating within the Tismana Quarry, two drilling rods are being run at an average flow rate of 70-90 mc/h, with 9-11 drainage, evacuating 4600 thousand m3/year, ie 532 m3/h. 2. The rational limits of day-to-day operations Determining the rational limits of the career and its maximum economic depth is a particularly important problem and needs to be resolved before the exploitation begins. If the position of the deposit corresponds to that of the land surface and the thickness of the discovery is small, the start of the works is obvious. If, however, under the analogous conditions of settling the deposit, the thickness of the discovery is high, it is not excluded an advantageous exploitation of the deposit by underground mining works. Parallel to the increase of the thickness of the discovery of medium and large inclines, the volume of the rocks that must be increased Extracted and removed, which leads to increased exploitation to date. When determining career boundaries and choosing how to work in day-to-day operations. Several factors of influence are considered, such as: - shape and geometrical characteristics of the useful mineral body; - the settlement of the deposit against the surrounding rocks; - Physical-mechanical properties of useful minerals and rock; - tectonics of the deposit and the rock; 235 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X - the quality of the useful mineral, the operating losses and the impoverishment during the operation; - the dynamics of the production and the land to achieve the planned production; - climatic and operational conditions of operation. The main indicator determined in assessing the economic effectiveness of mining works to date is the coefficient or ratio found. By coefficient of discovery is meant the value of the volume ratio of sterile rock required to be extracted and removed for each unit of useful mineral substance. Depending on the reserve to which the volume of waste required to be extracted and removed is calculated the geological coefficient of the uncovered and the industrial coefficient To discover. The geological coefficient or ratio to be discovered is the ratio of the total volume of sterile rock required to be removed from the geological reserve volume of the useful mineral material within the perimeter of the perimeter of operation. The geological coefficient to be discovered, K can be represented by one of the ratios: (m3/m3) (1) or (m3/t) (2) For a horizon of day-to-day exploits, the expressions of the geological coefficient to be discovered appear under the forms: (m3/m3) (3) or (m3/t) (4) In which: B, ΔB - the volume of sterile rock required to be removed, m3; A, ΔA - reserve of useful mineral substances, m3; C - the volumetric weight of the useful mineral, t/m3. The coefficient or industrial ratio to be discovered is the ratio of the volume of waste rock excavated and removed to each unit of industrial useful mineral material. Generally, the resulting sterile rock in the up-to-date exploits of the removal of the cover formations, the widening of the slopes and the removal of the sterile intercalations included in the thickness of the substance Useful minerals, in the form of intermediate strands, the proposed interaction, lenses. The industrial coefficient to be discounted is calculated as follows: - on average, on the deposit (on the pit); - on the horizon or extraction stage; - for a certain period of career activity; - at the operating depth limit to date. 3.Calculation of the medium coefficient to discover The average uncovered coefficient represents the ratio between the volume of the waste rock and the mineral reserve of the entire operating field or one of its sectors. 236 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X (m3/m3) (5) or (m3/t) (6) The industrial reserve of useful substance is less than the total balance sheet due to reserves designed to remain in areas banned from exploitation and reserves lost through exploitation (extracted with discovery, left as slices and inadvertently left in the exploited space). If in the perimeter of operation are not designed reserves, to remain in areas forbidden to exploitation, the industrial reserves will be given by the relation: (7) where: Ap = 0; Aex= A A1 = A(1-λ) (8) where: λ-loss ratio. Knowing that 15 million m3 of tailings and 1 mil m3 of useful mineral substances are contained in the volume of the capital works executed for the opening of the quarry, it is possible to determine the value of the average coefficient of discover for the whole quarry and the value of the coefficient of the discover environment for the quarrying period, knowing: - the volume of tailings contained in the contour of the quarry; - the useful volume contained in the career contour. The average coefficient of discovery for the whole quarry is determined with the relation: (m3/m3) (9) (m3/m3) (10) The average coefficient to be discovered for the period of exploitation of the quarry is calculated with the relationship: (m3/m3) (11) Where: BC and AC - sterile volumes and useful extracts for the execution of the capital opening works of the quarry. 4. Calculation of the limited co-efficient from the economic position The economic limit coefficient is the maximum allowable coefficient k2 in an operating method. In quarrying, there is a steady increase in total unit cost, as the pit grows, due to the increasing volume of tailings, which must be removed to extract a tonne of useful substance.The calculation ratio of the maximum permissible lag is: (m3/m3) (12) 3 where: Cad – The cost of extracting a tonne or m of mineral useful underground, lei/t or lei/m3; a - the cost of extracting a tonne or m3 of useful mineral material through day-to-day exploitation, without taking into account the costs for the extraction of waste rock, lei/t or lei/m3; b - expenditures for the extraction of one m3 of sterile rock, during the day-to-day exploitation, lei/m3. For a horizontal lignite layer located on the slope of a hill, with the working front length L = 1200 m, the layer thickness m = 8 m, the slope angle of the working front α = 40˚ 237 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X and the thickness of the opening H = 80 m, It is possible to determine the average uncovered ratio and the ratio of the last extraction horizon if known: - the maximum admissible planned cost of the lignite tonne extracted by works, Cad = 90 lei/t; - the cost of extracting a tonne of lignite without taking into account the discounted expenses, a = 18 lei/t; - the cost of extracting a m3 of discover, b = 15 lei/m3; - coefficient of extraction, n = 0,95. To determine the average discovered ratio, use the relationship: (m3/t) (13) where: The average industrial ratio will be: (m3/t) (14) The discovered report of the last drawing horizon is calculated using: (m3/t) (15) The limit of uncovered ratio is determined with the relationship: (m3/m3) (16) Conclusions By comparing the average industrial ratio, Kimedwith the limit of discover ratio, KLit is noticed that the latter is higher (Kimed References [1] Nicoleta MariaMihuţ, Modern methods for measuringthecapacity of transportinghigh- capacitybands, SITECH PublishingHouse, Craiova, 2008, ISBN 978-973-746-788-1 [2] Nicoleta Maria Mihuţ, Aurora Cătălina Ianăşi, Installation for determining the nature of excavated material from the high-capacity belts of mining basins, International Conference Mod Tech 2013, june 2013, Sinaia Romania, indexai ISI - Advanced Materials Research Volume: 837 Pages: 122-127 Published: 2014 [3] Dumitru Fodor, Modern methodsandtechnologies in surfaceexploitation. Achievementsand Performance, AGIR PublishingHouseBucharestand Corvin PublishingHouse, Deva, 2012 [4] Martian Murgu, FieldAssessment, TehnicalPublishingHouse, Bucharest, 1986. [5] Dumitru Fodor, Exploitation of mineral depositsandusefulrocksbyworksupto date, vol. 1, 2, TechnicalPublishingHouse, Bucharest, 1995. [6] XXX, Mine Engineer's Manual, vol. I-V, TechnicalPublishingHouse, Bucharest 238 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X STUDIES ON WASTE MANAGEMENT IN PESTISANI COMMUNE, GORJ COUNTY Ramona Violeta CAZALBAȘU, Camelia CĂPĂŢÎNĂ „Constantin Brâncuşi― University of Tg-Jiu, Faculty of Engineering, 3, Gorj, Romania Abstract: Population growth, raising living standards and providing in creasingly larger consumer needs undermine the balance of ecology through the waste resulted from daily life. Waste from household garbage deposited on the streets, the ones randomly disposed of at the edges of forests , mountains, orchards and pastures or more severely thrown into lakes or rivers, represent a real danger to the future of society by influencing the quality of the natural environment and changing its quality as well as its evolutionary progress. This paper presents studies on waste management in the commune of Peştişani in Gorj County. Keywords: waste management, rural, Pestişani 1. INTRODUCTION Waste management refers to activities concerning the collection, transportation , treatment, recycling and disposal of waste. In our country sanitation in rural areas is still in the project phase for the future, with administrative bodies still not finding funds for these projects. Waste and residues are nowadays working materials from which recoverable substances must be extracted. The administrative territory of the Peştişani Commune is located in the northwestern part of the Gorj County, at the foot of the Southern Carpathians, namely in the contact area between the Vâlcan Mountains and the OltenianSubcarpathian Depression, along the Bistrita River. This commune is located 21 km away from Târgu-Jiu, forming a rectangle with its large vertical side, measuring north to south a maximum distance of 29 km and from the west to the east a maximum distance of 8 km. The commune is located along the Bistrita River, with north-south orientation, and the villages are situated on the river terraces, which are more emphasized in the eastern part because in the eastern area the hills come down close to the water. Thanks to the hydropower facilities on the Bistrita River, the area is protected from floods, these risks being avoided. 2. DEMOGRAPHIC AND SOCIAL PROBLEMS The evolution of the population recorded over a longer period of time shows a decrease in the population, as shown in Table 1: Table 1. Population of Pesteşani commune Number of inhabitants 1977 1980 1985 1992 1994 1996 2002 Census census census Total commune 5126 4683 4551 4261 4082 4895 4248 Pestişani 1650 1598 1465 1198 1212 1479 1278 Boroşteni 580 520 515 569 517 602 504 Bradiceni 896 783 795 730 712 842 746 239 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Francesti 775 680 688 708 695 898 799 Gureni 497 441 441 520 410 414 430 Hobita 350 315 311 309 307 420 325 Seuca 378 336 336 227 229 240 166 On the whole, in the commune (with quite large differences between the villages), the growth index in relation to the population census in 1977 is negative in all localities. The population density is 20 inhabitants / km2, lower than the county average densities (71 inhabitants / km 2),,which characterizes the space of a low concentration of the population being below the average in a rural district (47.00 inhabitants / km 2) and of a very high surface area in territory that is not occupied (the mountains). The population of the commune Pestisani, on large age groups, approaches the county average and is presented in table no. 2 Table 2. The population of Pestişani commune by age groups Total Age groups population 0-16 years 16-60years Over 60 years No inh. % No inh. % No inh % County 401021 97727 24.37 242419 60.45 60875 15.18 Pestişani 4261 831 19.5 2471 58.0 959 22.5 Based on the data collected by the County Statistics Department, the population of 0-16 years decreases in number and weight (by about 2%) and the population of 60 years and over (figure no. 1) increases (by about 3.5%) Fig. 1. Pestişani commune population by age groups 3. WASTE CATEGORIES IN PESTISANI COMMUNE The local authorities are the ones dealing with waste management in Pesteşani. This is regulated by the Law on Local Public Administration No. 215/2001. Although this is regulated by law, local authorities consider this issue very important for the sustainable development of the commune, but it remains at the level of an issue yet to be solved. 240 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Landfills in the locality cause multiple environmental damage, as toxic emissions can spread through air, soil and water. Microorganisms and other harmful animal resulting from waste can cause illnesses and other side effects to people living in multiple environments. Domestic waste, according to the bigger share of their constituent components can be divided into the following categories: - Waste with high content of high calorific material: paper, cardboard, cloth, rubber, plastic, etc. content ranging from 20-60%. Waste with a high content of vegetable elements: corn stalks, hay, grape vines, content ranging between 60-70% and with a total humidity of 50-60%. Other types of waste - wood waste in the form of dust or sawdust, having a calorific value in the range 7500 to 20000 kj / kg, with a high content of wood-specific volatile substances - Vegetables made from strains, straw or seed husks. Higher recovery of these wastes can be done in the direction of feed preparation or in industry. Wastes from the dispensary units. It is important to burn them at high temperatures so that all organic materials and sharp objects are completely destroyed. If they cannot be burned, they must be carefully buried in the storage platforms: a pit must be made in the waste previously stored then the hospital waste must be carefully covered after it has been placed in its entirety there in order to avoid contact with the workers from the storage platforms. 4. TREATMENT OF WASTE In the European Union there are many methods of treatment, of which we recommend the biological treatment that is non-polluting for the rural area. Composting and biological treatment of waste is based on the decomposition of organic substances from waste under the action of microorganisms. By biological treatment, both recovery and removal of residues are achieved. By composting the waste is transformed into a non-polluting product with high nutritive value for plants and a very good addition to the physical and chemical state of the soils. The transformation of waste into compost used in agriculture has been known in practice for about 7-8 decades, especially since the populated centers have experienced significant development. Although many research and preparation processes have been carried out so far, the composting problem remains current and continues to be studied, both independently and together with other waste-recycling methods. Waste is very heterogeneous, which requires some preparation to be transformed into compost. This preparation, consisting of the homogenization of the waste to be treated, its shredding and the separation of undesirable waste into the compost mass, constitutes the mechanical preparation. CONCLUSIONS Waste management is one of the most acute problems both at national , European and world level, and therefore consideration should be given to the analysis of problem areas with regard to the 241 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X quantity of waste produced but especially the way it is stored , which is often wrong and jeopardizes the smooth running of life. An important step to be taken is educate the population in this regard, by issuing brochures, waste pollution prevention programs, engaging the population in "non-profit" activities to clean up the areas where waste of human activity is stored. The need for the construction of an ecological landfill site exists because the quantities of waste are high and their storage is random or in the valleys of the Bistrita and Bâlta valleys and rivers. Appropriate management of the waste would fully solve the problem of the waste produced within the commune, it would provide a cleaner, less polluted way of life and would also bring economic and social benefits, by creating new jobs. REFERENCES 1. C. Capatana, Claudia Maria Simonescu - "Storage, Treatment and Recycling of Waste and Recoverable Materials", MATRIX ROM Publishing House, Bucharest, 2006; 2. C. Căpăţînă, C. Racoceanu - Waste, MATRIX ROM Publishing House, Bucharest, 2003; 3. Tiberiu, A. - Waste Management and Their Impact, Ed.Primtech Bucharest, 1998. 4. Mănescu, S. - Environmental hygiene, ed. Medical, Bucharest, 1981. 5. Rojanschi, V., F. Diaconu, Gh. - Environmental Protection and Hygiene, Ed.Economica, Bucharest, 1997. 6. Brown; Lester R.- Global Problems of Humankind, Technical Publishing House, Bucharest, 1994.Archives of Pestişani Town Hall. 7. The General Urban Plan of Pestişani Commune 2003. 8. Ministry of Waters and Environmental Protection, National Institute of Research and Development for Environmental Protection - ICIM Bucharest - "Study on Waste Management Methods and Technologies"; 242 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X STUDY ON WATER QUALITY INDICATORS AT TAIA TREATMENT PLANT HUNDEDOARA COUNTY Ramona Violeta CAZALBAŞU, Camelia CĂPĂŢÎNĂ, Cîrţînă DANIELA "Constantin Brâncuşi" University of Tg-Jiu, Faculty of Engineering, 3, Gorj, Romania; Abstract: Water is consumed in its natural form or in a processed one. It is a well-known fact that enterprises, institutions, energy and agriculture consume it as processed water whereas the population consumes it as drinking water or wastewater. This paper presents the study of water quality indicators from the treatment plant Taia in Hunedoara County. The following quality indicators were determined: turbidity, hardness, alkalinity, chlorine oxide and organic substances. The determined quality indicators revealed that they fall within the limits set by legislation, with some exceptions. In each step of purification of organic substances there has been a continual reduction, this being carried out both biologically because of the biomass deposited on sand grains in the filter bed as well as especially during the oxidation step with active chlorine. Keywords: water treatment, indicators, Hunedoara. 1. INTRODUCTION The complexity revealed in the water molecule, its participation in the multitude of vital processes, should draw a tremendous attention to rational use of the resources. On the contrary, in fact, it is still prevalentan erroneous idea that water sources are inexhaustible, therefore no difficulty is encountered in this respect. Water "is everywhere" in the seas and oceans, the rivers, the glaciers, ponds and underground layers. However water does nolonger seem unlimited. Present and future needs require cautious interpretation of global quantitative data. Only a small part of the total amount is directly usable and precisely this amount is seriously threatened by pollution. Among the three main forms of existence of the water - air, surface and underground, there is a close relation due to a certain order of succession of the known natural phenomena: evaporation, condensation, infiltration and leakage. Solar energy occurs significantly to achieve the water cycle; it is the determining factor in the formation of atmospheric vapor and even part of the soil. A number of calculations have shown that in the course of a year, the land area of 1 m 3 receives about one million kcal of solar energy, heat, able to vaporise the water layer thickness of 1.30 m 1. After evaporation, the wind ensures the circulation and distribution of water vapor in the atmosphere. Depending on the temperature and degree of saturation of the air, the water can condense into very fine particles (mist) or coarser particles, liquids and solids (clouds). In favorable conditions, the clouds give rise to precipitation falling on the earth's surface as rain, hail or snow. A part of the water precipitations falls in rivers, seas and oceans, where the cycle starts again by evaporation, whereas the other part of the condensed water arriving on dry surface follows different paths. 243 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Thus, about one-fourth of it forms streams or torrents, or it flows through streams and rivers into seas and oceans. Approximately half of the water from precipitation, after reaching the heated land, evaporates. This happens particularly where there is no possibility of being transported into seas or oceans (Sahara). To this evaporated water it is added that derived from animal and plant transpiration. Fig. 1. Water cycle in nature and in different fields of application Another part of the rain water fallen on the dry land (about 25%), penetrates into the soil, raising the level of underground waters or increasing the flow of underground sources. Also, in addition to the soil water that can be incorporated in the soil by capillary action or evaporation, it may form small underground rivers too. It should be remembered that a very small fraction of water precipitations falls on the ground as snow that melts or forms glaciers. Besides those from infiltration, groundwater can be fossil water, preserved in the geological water-tight and juvenile layers synthesized in the depth of the earth's crust. Taking into account the water use in various industries, its circuit is completed as shown in Figure 1. This paper presents the study of water quality indicators from the treatment plant Taia in Hunedoara County. EXPERIMENTAL Turbidity was determined experimentally with MicroTPI portable turbidimeter. PH was determined with the experimentally determined pattern portail Hanna pH meter (4) The alkalinity of water was determined experimentally by titration with 0.1 N HCl, in the presence of phenolphthalein or methyl orange indicators. The determination of chloride was carried out using the argentometric method. The determination of oxidizable organic substances in the water was performed using the KMnO4. 244 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Total hardness was determined by complexing the metal cationsCa 2+ and Mg 2+, which forms the hardness with the disodium salt of ethylene diamine at pH 10 in the presence of Eriochrome Black T indicator. RESULTS AND DISCUSSIONS In order to characterize the water treatment plant operation Taia the data presented in tables.1 şi.2 represent the average data for five months of the year on various monitored quality indicators. Table 1. Water quality indicators in months: December- February and March to April Raw water settled water filtered water Water Mains CMA NTU turbidity 2.6 1.7 34.1 7.50 1.39 1.7 9.23 7.4 1.9 1.4 3.5 3.2 1.83 1.2 3.4 2.9 ≤5 degrees HCL alkalinity 0.3 0.82 0.50 0.44 0.3 0.8 0.49 0.4 0.3 0.35 0.47 0.40 0.33 0.32 0.35 0.32 mL / L Chloride 11.5 11.4 11.3 10.5 11.4 10.4 10.7 10.4 11.4 10.64 11.74 11.05 10.8 13.66 10.35 10.76 250 mg / L Means org mg 1.1 1.17 6.56 2.27 1.26 1.1 5.30 2.12 0.9 0.81 1.13 1.12 0.9 0.58 0.94 0.68 O 2 / L ≥6,5 pH 7.2 7.1 7.8 7.6 7.2 7.2 7.5 7.5 7.2 7.4 7.5 7.5 7.1 6.9 6.9 6.9 ≤9,5 Total hardness 1.16 1.06 1.30 1.21 1.06 1.06 1.32 1.18 1.16 1.18 1.02 1.19 1.06 1.08 1.13 1.18 5 hardness degrees Table 2. The quality indicators for the raw, decanted, filtered and network water Raw water settled water filtered water Water Network CMA NTU turbidity 24.3 9.0 7.04 4.71 9.14 7.24 4.86 3.14 2.79 2.4 3.24 3.13 1.83 1.34 2.86 2.41 ≤5 degrees HCL , alkalinity 0.40 0.41 0.4 0.48 0.4 0.4 0.35 0.47 0.38 0.36 0.37 0.35 0.35 0.35 0.31 040 mL / L Chloride 11.3 12 11.3 9.93 10.6 12.7 12 11.3 9.93 10.6 12.7 12 11.3 9.93 10.6 14.1 250 mg / L Means org mg 5.56 2.27 2.15 1.65 1.49 2.30 2.12 1.89 1.57 1.13 1.18 1.26 0.36 0.97 1.14 1.1 O 2 / L ≥6,5 pH 7.8 7.7 7.6 7.5 7.7 7.5 7.6 7.4 7.3 7.6 7.5 7.5 7.4 7.4 7.1 7 ≤9,5 Total hardness 1.30 1.20 1.16 1.12 1.08 1.32 1.19 1.17 1.1 1.08 1.32 1.18 1.13 1.1 1.18 1.25 5 hardness degrees 245 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X From the data obtained it is seen that in the case of higher turbidity of 20 NTU over conditions given in the reactive coagulants (Al sulphate and lime for pH adjustment) treatment efficiency is of 62.38% in comparison with the case where no positive coagulants is administered, and the efficiency is only 16.14%, which is 3.86 higher because of the influence of coagulants in the process of sedimentation (2). The differences remain in the other steps of treatment, and the total efficiency of the entire apparatus in the first case is 92.46%, while in the second case only 60.70%. It should be noted that in both cases the treated network water falls under quality requirements regarding its turbidity. The turbidity of raw water triggers off the frequency in the washing of filters. As the alkalinity measured by titration with hydrochloric acid is concerned it is noted that the process using solid content does not change so that the overall efficiency is only 5%. Chloride content gradually increases from the water source into the network water, which is particularly difficult to explain since, up to the disinfection with chlorination stage, hardly any chlorine based chemical is used. In these circumstances we believe there are experimental errors andtherefore the treatment efficiency could not be calculated properly. Free residual chlorine must be found only in the network water, being an indicator of water quality certifying the oxidative destruction of microorganisms. As for the content of organic substances in the raw water after each treatment step, measured in mg O 2 / L the treatment efficiency was calculated as follows: For worst case treatment efficiency is calculated in three steps, namely: Q T treatment efficiency in the settling step I: SOr1 SOr2 5,56 2,30 SOrD 100 100 58,63% SOr1 5,56 Q T treatment efficiency in the filtration step II: SOr2 SOr3 2,30 1,13 SOrF 100 100 50,86% SOr2 2 ,30 Q T treatment efficiency in the chlorination step III SOr3 SOr4 1,13 0,97 SOrCL 100 100 14,15% SOr3 1,13 Total efficiency: SOr1 SOr4 5,56 0,97 SOrTOTALE 100 100 82,55% SOr1 5,56 246 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X With respect to organic matter present in water there is a continuous decrease observed in each stage of treatment, the reduction being done both biologically due to the biomass on the sand grains deposited in the filter bed and in the oxidation step with active chlorine. Thus, the overall treatment efficiency for the organic substance content is 82.55%. The pH for the worst-case treatment efficiency is calculated in three steps, namely: - treatment efficiency in the settling step I: pH1 pH 2 7,8 7,5 pH D 100 3,84% pH1 7,8 - the effectiveness of treatment in stage II filtering: pH 2 pH 3 7,5 7,6 pH F 100 100 1,33% pH 2 7,5 - the efficiency of the treatment in the chlorination step III: pH 3 pH 4 7,6 7,1 pH CL 100 100 6,57% pH 3 7,6 Total efficiency: pH1 pH 4 7,8 7,1 pH total 100 100 8,97% pH1 7,8 In the process used to treat water the pH is within the quality limits during the whole process oscillating around neutral value in the network water. CONCLUSIONS Free residual chlorine, which is an indicator of water quality showing the destruction of microorganisms by oxidation, must be found in the network water. There is a continuous drop in each stage of purification of organic substances, reduction being both biological carried out by the biomass on the sand grains deposited in the filter bed and especially during the oxidation step with active chlorine. The filtering operation is influenced by two categories of factors: characteristic factors of the influent and of the filtered. Double filters (by flow) occurred due to the need to improve current performance of rapid filters with up or down current. By combining the two-way filtering productivity is achieved at filtering stations. The improvementin water filterability at water treatment plantTaia in Hunedoaracounty is achieved by replacing existing filters with fast filters. 247 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X BIBLIOGRAPHY 1. C. Teodosiu, Industrial and Drinking Water Technology Matrix Rom, Bucharest 2001 2. M.Negulescu, Treatment of Urban Wastewater, Ed Tehnica, Bucharest, 1974 3. V. Rojanschi,Th. Ognean–The guide for wastewater treatment plant operator, EdTehnica, Bucharest1997. 4. Intraenvironment, Faculty of Chemical Industry, Environment Quality Control, Workings of practical laboratory, CarteaUniversitara, 2003 5. Antoniu R, Bondor D.,ConstantinescuGh, Ghederim V., Marcu M, Negulescu M, Popescu V,.- Industrial Wastewater Treatment, vol. 1, Ed. Tehnica, Bucharest, 1987. 6. Water Law 107/1996 - Official Gazette 244 / 10.08.1996. 7. Cirtina Daniela 2005 Water Pollution, Ed Sitech. 8. NTPA 002. Quality indicators of wastewater discharged into the sewage network of cities 248 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X STUDY TO DETERMINE A NEW MODEL OF THE ISHIKAWA DIAGRAM FOR QUALITY IMPROVEMENT Prof. Ph.D. Liliana LUCA, Assoc. Prof. Minodora PASARE, Lecturer Ph.D. Alin STANCIOIU „Constantin Brancuşi‖ University of Tg-Jiu, [email protected] , [email protected] , [email protected] Abstract.The paper presents the results of a study concerning the use of the Ishikawa diagram in analyzing the causes that determine the improvement of the quality of education in a university. All the possible, main and secondary causes that could generate the studied problem were identified. We determined six possible main causes: Man-professor, Man- student, Methods, Materials, Environment for Teaching and Learning, Quality Management. All main causes and secondary causes described a new Ishikawa diagram, a new model with 4 M + 1E + 1Q. Keywords: quality management, diagram, Ishikawa, quality of education 1.Introduction Improving the quality of manufacturing processes can be performed by using some specific methods and techniques of analysis (Pareto Analysis, Ishikawa Diagram, Histograms, etc.). The diagram is considered one of the seven basic tools of quality control [6]. Ishikawa Diagram is a simple graphical instrument to understand the causes that produce quality defects and is used to analyze the relation between a problem and all possible causes. All categories of causes start with the letter M (machines, methods, men, materials, maintenance, milieu-environment, management) for the productive domains. 4M, 5M, 6M, 7M Ishikawa diagram were performed like this. The cause-effect diagram – fishbone or Ishikawa - was developed by Kaoru Ishikawa in order to determine and divide the causes of a given problem on main fields of causes. It is recommended to use it only when there is only one problem, and possible causes can be classified based on several criteria. Ishikawa diagram is being defined as a graphic representation that schematically illustrates the relations between a specific result and its causes, [1], [6]. The studied effect or negative problem is ―the fish head‖ and the potential causes and sub-causes define the ―fish bone structure". The Ishikawa diagram can be applied for the analysis and evaluation of a quality problem in different production activities as well as in the field of services rendered to the beneficiaries. An interesting model of Ishikawa diagram was developed in the case of a defect occurred after a service car repairing [8]. In [13] it is shown that obtaining a correct diagram is possible only through working in a team with experience. Ishikawa diagram application areas are continuously expanding. For example, nowadays the method is also being applied in the medical field [7]. A study on Identification and Classification of Causes which Generate Welds Defects it is presented in [12]. Studies of Applying a Quality 249 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Management Tool for Solving Non-conformities in a Automotive are presented in [9] and [11]. In [10] it is given Ishikawa diagram for public order services. The paper presents the results of a study concerning the use of the Ishikawa diagram in analyzing the causes that determine an issue in the field of education - "improving the quality of education in a university". Improving the quality of educational services must be a permanent concern so that educational services in universities respond to the requirements and needs of students and employers. Universities must set up and implement actions to fully meet the requirements of stakeholders (internal and external customers). In order to establish measures for the continuous improvement of educational processes, all the potential causes that influence them must be identified. For the full satisfaction of stakeholders, universities need to design and implement efficient and effective quality management systems. 2. Method and results The research method used to determine Ishikawa diagram is based on work steps proposed by Dale [3], namely the following: - It is defined very clearly the effect of the problem considered, - It is written the effect in the right and it is drawn a line from right to left, - It is checked if each team member has understood well the problem, - They are determined the main categories of causes which are the main branches of the diagram, - It is organized a brainstorming session to determine possible secondary causes, - It is organized another brainstorming session in order to discuss in detail the causes and to determine those who have the major degree of probability for producing the studied effect, - They are traced and recorded the appropriate sub-branches. The above steps have been taken and were identified several potential causes that were grouped into 6 main categories and 6 families respectively (table 1). Tabel 1. Main and secondary causes The studied problem Main causes Secondary causes 1. Man- Professor - Professional training - Pedagogical abilities - Pedagogical talent - Human qualities - Interactive communication skills - Skills to stimulate creativity 2. Man- Student - Active - Disciplined - Appropriate behavior - Interest in assimilating knowledge in the field of training - Attitude - Abilities 250 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X - Appropriate courses and applications Improving the quality of 3. Materials - Appropriate teaching materials education in a university - Modern laboratory equipment - Internet access - Provision of the necessary information on time - Very well-equipped library and reading room - Appropriate teaching strategies 4.Methods - Teaching methods appropriate to the type of discipline - New teaching technologies - Classic evaluation methods replaced by modern methods - Appropriate teaching and assessment methods for the development of teamwork and communication skills - Appropriate teaching and assessment methods for developing computer skills - Appropriate teaching and assessment methods to develop practical skills specific to the future profession - Attracting students to extracurricular activities - Advice and permanent orientation of students - Developing activities coordinated by the student's year manager - Aesthetic and functional teaching 5. Environment for spaces Teaching and - Modern teaching and stimulating Learning learning spaces - Modern libraries with flexible program - Functional and stimulating reading rooms - Accommodation in modern homes - Modern sports base - Proper medical office 6. Quality - Improvement of the periodic internal Management evaluation of study programs - Improving the periodic evaluation of teachers 251 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X - Improving the assessment of the learning environment - Improving student assessment and assessment procedures - Transparency of public interest information - Improving the activities of the quality assurance structures - Regular review of quality assurance procedures 3. The Ishikawa Diagram based on the study Based on the study, a new model for the ISHIKAWA diagram is proposed, with the following 6 main causes: Man – Professor, Man- Student, Materials, Methods, Environment for Teaching and Learning, Quality Management. Given the names of the main causes, the diagram can be called: The Ishikawa diagram - model 4M + 1E + 1Q. The diagram of the Dale stages in [3] is presented in figure 1. The obtained diagram gives an overview of the objective and subjective causes that lead to the improvement of the quality of education in a university. Once the causes determined it can be adopted and applied the necessary measures to improve the studied problem. 4. Conclusions The external environment of universities is subject to complex shaping actions and forces, so students and employers will increase their demand for the quality of educational processes. The quality of education will be a permanent requirement for universities wishing to remain in national or international academic space characterized by fierce competition between universities. To improve the quality of education, the best decisions and the most appropriate measures that influence the educational process should be taken. In this regard, all causes that determine the effect called: Improving the quality of education in a university. The Ishikawa method by which the cause-effect diagram is done is a good way to find the best solutions for improving the quality of education. The Ishikawa diagram has the advantage that it offers the possibility to identify and analyze all factors of an objective and subjective nature, which relate to the studied problem. The use of Ishikawa diagram leads to a graphical illustration of the existing relationships between a problem appeared in the educational process and the potential causes (factors) that influence this result, which helps to better understand the relations between a studied problem (Improving the quality of education in a university) and the causes that determine it. 252 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Fig. 1. The Ishikawa diagram - model 4M + 1E + 1Q 253 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X References [1] American Society for Quality, Fishbone diagram.http://www.org/learn-about- quality/cause-analysis-tools/overview/fishbone.html [2] Cananau, N., Sisteme de asigurarea a calitatii. Editura Junimea, 1998, pp121-126. [3] Dale , B. G., Managing quality (2-nd Ed.), Prentice Hall, 1994 Horls. [4] Ilie G.,Ciocoiu C.N.,Application of Fishbone diagram to determine the risk of an event with multiple causes. Management Research and Practice, Vol. 2 Issue 1 (2010) p: 1-20. [5] Ionita, I., Managementul calitatii si ingineria valorii. Editura ASE Bucuresti, 2008, pp186-187. [6] Ishikawa K, Loftus JH, (Eds): Introduction to quality control Tokyo, Japan: 3A Corporation, 1990 [7] Kam Cheong Wong, Using an Ishikawa diagram as a tool to assist memory and retrieval of relevant medical cases from the medical literature. Journal of Medical Case Reports 2011, 5:120. http://www.jmedicalcasereports.com/content/5/1/120. [8] Luca, L., Study on the determination and classification of the causes that determine the faulty operation of a vehicle fuel pump. Recent Researches in Manufacturing Engineering. 3- rd WSEAS International Conference OnManufacturing Engineering, Quality and Production System (MEQAPS‘11). Published by WSEAS Press, 2011, ISBN 978-960-474-294-3, pp. 21- 24. [9] Luca L., ,Stancioiu A., The study applying a quality management tool to identify the causes of a defect in an automotive. Proocedings of the 3-rd International Conference on Automotive and Transportation Systems. Montreux, Elvetia, 2012. ISBN 978-1-61804-146-3. [10] Luca, Liliana; Filip, Cornel-Petre, On the assesment of the public order services quality by using classic instruments of quality management. 17TH INTERNATIONAL CONFERENCE THE KNOWLEDGE-BASED ORGANIZATION, CONFERENCE PROCEEDINGS 1: MANAGEMENT AND MILITARY SCIENCES, Book Series: Knowledge Based Organization International Conference Pages: 691- 696 Published:2011 [11] Luca L., The Study of Applying a Quality Management Tool for Solving Non- conformities in a Automotive. Conference ImanE 2015 , Iași, Romania. Applied Mechanics and Materials, Vols. 809-810, Trans Tech Publications (Switzerland),2015,ISSN: 1662-7482, pp 1257-1262. [12] Luca, L, Cirtina, L, Stancioiu, A, Study on Identification and Classification of Causes which Generate Welds Defects. Innovative Manufacturing Engineering Conference (IManE) , Chisinau 2014. Applied Mechanics and Materials Volume: 657 , Trans Tech Publications (Switzerland), 2014, Pages: 256-260, Published: 2014 [13] Paraschivescu, A.O., Managementul calitatii. Editura Tehnopress, Iasi, 2006., pp.155- 156. [14] Pruteanu, O., Managementul calitatii totale, Editura Junimea, Iasi, 1998, pp.166-167. [15] http://www.cityprocessmanagement.com/Downloads/CPM_5Ys.pdf [16]http://www.nursingtimes.net/Journals/2013/04/12/k/x/z/Using-fishbone-analysis--to-investigate- problems-160413.pdf 254 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X EMISSION IMPACT ASSESSMENT FROM TURCENI POWER PLANT ON THE HEAVY METAL POLLUTION OF THE SOIL Delia NICA BADEA* Constantin Brâncusi University of Târgu – Jiu, Faculty of Medical and Behavioral Sciences, 30 Calea Eroilor, 210135, Târgu - Jiu, Romania. Abstract. For evaluation environmental impact of emissions resulting from the combustion of lignite for thermo- energetic purposes the sampling was done in order to follow the evolution of heavy metal concentration of solid fuel use, the ash from the filter within the ash and slag heap, the soil adjacent to potential sources of heavy metal emissions power plant and landfill. This paper presents the methodology of sampling and heavy metal pollution level Zn, Cu, Mn, Pb, Ni, Cd, Co, Hg in the area of coal power plants (CET Turceni) in 2010. In this sense, quantitative analysis of metals in ash, soil and plant products, was achieved by modern instrumental techniques Atomic absorption spectrometry (AAS). To assess the time evolution of the level of heavy metals in the soil are presented and the results of physico-chemical and biological weapons made in 1997, 2000, 2010. Soil of the coal-fired thermal power plant is a ground with anthropogenic load of heavy metals, especially Cu, Pb, Ni Cd, Zn whose range values exceed the background content and even the limit for sensitive soils (Pb). Keywords: heavy metals, pollution, soil, thermal, AAS, coal. 1.Introduction A number of plants, in this case, herbaceous vegetation, vegetables, fruit can be used as biomonitori of pollution in general, especially heavy metals by chemical analysis of the components of adjacent sources of pollution produced by combustion of plants coal power plants. Energy installations, particularly power plants using coal as fuel, can affect the environment, sometimes leading to damage to the ecological balance in areas where they are located, they present a complex impact on all environmental factors in their immediate area (air, water, soil, flora and fauna, food and interior), so energy is considered as the main source of pollution. The main polluter of the zone of influence is the power plant ashes. Fly ash removed by the chimneys, dust, wind-blown fine ash heaps of slag, coal ash and dust deposits from the coal-transport and its preparation is solid with a contaminant, which is available in the form of aerosols. If the ash resulting from burning coal has a composition and a low content of heavy metals (Zn, Cu, Mn, Cd and Ni, Pb, Co, Hg), aerosols formed are non-toxic. In terms of harm, they are important only in large quantities. Monitoring of environmental pollutants include compounds for investigating multiple areas - air, water, soil, vegetation in urban and in rural areas. Number of species of pollutants, their distribution involves sampling and analytical methodologies strategies investigation in particular the development, implementation and application of these methods in environmental programs. Sampling and methodology of investigation of environmental pollution in general, the degree of pollution near the sources of pollution, is achieved by identifying potential sources of pollutants, the concentration of pollutants and their long-term monitoring of pollution and its rate [1-3]. 255 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Starting from literature data to assess the degree of heavy metal pollution, we aimed to investigate the concentration of heavy metals in coal ash primary (the filter), ash deposited in landfill, soil, the area of thermal power plants the solid fuel, coal: Turceni complex. In this respect, we have established areas of interest and application of sampling methodology for assessing the influence of emissions from the combustion of coal in the area Turceni CET by determining concentrations of heavy metals in the soil and vegetation. 2. Characterization area CET Influential area of power plant belongs to the Piedmont Piedmont, showing the character of the transition between the mountains and plains, both geomorphological and the conditions and resources of their recovery, the growth of settlements and landscapes. Thermal Power Plant is located in Meadow Jiu stall south of the river, close to it with Jiu-E about 1.5 km from the town of Upper Turcenii. The study area is characterized by increased drainage, which is favored by a clay MARMO loose rocks, clays, sands, gravels. The hydrographic network is continuously expanded and deepened under the action of tectonic factors, climatic and work. In terms of climate, mainly under the influence of Mediterranean climate, with circulation of the southern and western part, by interfering with air traffic corridor Jiu NW-SE direction. Temperatures and precipitation regime is influenced by oceanic air masses from the west, Mediterranean climate combined with the SW. The natural vegetation is represented by forests gradually shrank, leaving grasslands and agricultural crops. According to the document running [4], are known sources of environmental pollution of Turceni power plant. The main pollutants emitted into the atmosphere, contained in exhaust gases from burning fuel with air for combustion in boiler furnaces are: SO2, NOx, CO2, CO, particulates and unburned particles, traces of heavy metals (Hg, Sb, As, Pb, Cr, Co, Cu, Mn, Ni, V). concentration of mercury in flue gas will be below 0.05 mg / Nm3 and the sum of the Concentrations of heavy metals (Sb, As, Pb, Cr, Co, Cu, Mn, Ni, V) will be below 0.5 mg / Nm3. Business owner is required to provide data on the emission of other pollutants such as: CO, heavy metals, etc.. The main sources of pollution of soil and subsoil are: the coal storage; storage of oils, petroleum products; chemical storage; chemical water treatment plant and inner channels; deposit of slag and ash. Measures to prevent pollution of soil and vegetation: - installation of wetting of ash and slag heaps, to prevent the wind spulberării - maintenance of protective belts of trees and shrubs resistant built - temporary landfill compliant technology. 3. Experimental methods 3.1.Samples collection and preparation Turceni power plant in the area were sampled by solid fuel, ash and soil in accordance with specific geomorphological and lithological territory, the dominant direction of air currents, the positioning of both the power plant and ash landfill located west of the power 256 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X plant. In this sense, the sampling was done in order to follow the evolution of heavy metal concentration of solid fuel used in the primary ash filter, inside the heap of slag and ash, the soil adjacent to potential sources of pollutant emissions of heavy metals power plant and landfill. Samples were collected in accordance with the rules provided on the basis of analytical sampling requirements. 3.2. Quantitative Chemical Analysis Determination of heavy metals from soil by wet mineralization is concentrated strong acid and hydrogen peroxide: HNO3, HCl and H2O2 using digester MILESTONE . Procedure: - weigh 1 g vials of the mineralization of soil MILESTONE digester; - oxidant mixture is added: 6 ml 65% HNO3 + 3 ml HCl + 0.25 ml 35% H2O2 30%, the seals and vials of the mineralization starts; - steps program of mineralization (Table 1); - cool samples: 30 min ventilation; - to take samples in the digestion vessels at least 12 hours (overnight) covered with filter paper to avoid contamination; - filter samples in flasks of 50 ml (wash the filter with distilled water). Quantitative analysis of metals in ash, soil and plant products was achieved by modern instrumental techniques Atomic Absorption Spectrometry (AAS). Determination of heavy metals in soil was done according to the Handbook of MA079 Re.0/2006 MICROWAVE [5, 6]. Table1. Steps program of mineralization Stage Time (min) Power (W) Temp (C) 1 15 850 150 2 15 850 210 3 15 850 210 4. Results and discussions The research results mentioned above instrumental technique (AAS) for eight heavy metals in coal ash from the filter, dump the ash, soil and power plant adjacent to the dump are shown in Figure 1 (for lead) and Table 2 for contents globally [9,10, 11]. 257 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 258 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Fig.1. Technical rezults calibration measurement of lead by AAS. Table 2. Concentration levels of heavy metals - total forms solid fuel, ash and soil in the area TURCENI CET. Level 0-35cm Source: Synthesis Report, Research Contract No: 456/21.06.2010, analysis ICPA Newsletter Nr.3226 / 02.12.2010, Bulletin 65/2010 test. Nr. Specification Heavy metal concentration mg / kg (average val.) crt. Zn Cu Mn Pb Ni Co Cd Hg 1 Filter ash CET 12,1 65,4 502 47,9 79.0 13,8 1,024 0,037 2 Material 55,6 56,9 263 31,8 78,0 11,6 0,139 0,020 stockpile CET 3 Soil samples at 100 29,2 525 70,2 45,2 11,6 0,302 0,102 1000 m east landfill CET 4 Probe power 91,2 24,2 473 40,0 40,8 12,6 0,254 0,049 plant east ramp 4 Probe coal 56,5 21,6 132 31,4 30,3 5,79 0,331 0,019 deposit CET To assess the time evolution of heavy metal levels in soil we reproduce the results of physico- chemical and biological ( table 3) weapons made in 1997, 2000, 2010 [7, 8, 11]. 259 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Table 3.Values of heavy metals in soil, Turceni power plant area, years: 1997, 2000, 2010. Source: SC. ICEMERG SA, C4145/2000, 60709/1996. Level 0-35cm, Research Contract Report No: 456 / 21.06.2010. Nr.crt. Metalul Concentrations 1997 Concentration 2000 Concentration 2010 (ppm) (ppm) (ppm) 1 Cu 23-43,5 24-42 24,2 -29,2 2 Zn 63-123 58-224 91,2 - 100 3 Pb 38-48 25-45 40,0 – 70,2 4 Co 16-18,5 16-19,5 11,6 - 12,6 5 Ni 49-78 35-39 40,8 – 45,2 6 Mn 331-638 464-639 473 - 525 7 Cd 0,8-0,9 0,7-1,8 0,25 – 0,30 The heavy metals in the composition of the solid fuel, the lignite in the Jilţ Quarry are all found in the ash collected at the bottom of the filters, in the ash and clay in the heap and in the soil adjacent to the influence zone of the thermal power plant. The level of heavy metal concentrations in the soil adjacent to the thermal plant is within the normal limits except for: Cu, Pb, Ni, Cd, Zn whose range values exceed content level (normal). The maximum Pb concentrations resulting from performance analyzes in 2010 exceed the alert threshold for sensitive soils (OMAPPM 756) for the adjacent soil storage pit. Increases in concentrations of heavy metals specific to anthropogenic protosols in the zone of influence of the pool are determined both by the emissions from the chimney and by the coal dust and ash in the coal and shale landfill even if the collection and discharge into the dump is done by way of wet. The evolution of soil metal concentrations in the soil during the period 1997-2010, presented in Table 3, reflects maintenance at the same level (except for lead) or a slight decrease, which is the reason for our technical measures taken lately harm. 5.Conclusions Given that the ash dump is located in the western town Turceni, is expected to result in ash dry winds, causing the concentration of heavy metals in soil and plants and create the phenomena of pollution of the agricultural land area. Values of climatic parameters Turceni power plant area can be considered normal and does not present a significant influence on the accumulation of heavy metals in soil and plants. Ash has a considerable content of heavy metals, total-forms, which were higher compared with normal values for agricultural soils, but not at a level so high as to be limited for crop production. Soil Turceni power plant area is an additional anthropogenic soil laden with heavy metals, especially copper, nickel, lead, cadmium and zinc. Physico-chemical parameters of the soil retain these metals still inaccessible plant forms. This situation is temporary, whereas the impact of ash on the ground of this area longer determines the concentration of heavy metals in soil and plants. This fact shows that the pollution is still early, and therefore can not speak of a clear process of heavy metal pollution. The 260 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X phenomenon is amplified when human impact is extended, without taking specific technical measures. Control of the degree of heavy metal pollution Cu, Cd, Pb, Ni, Zn, Co, Mn, Hg from the soil adjacent to the coal-fired power plants (lignite) can be achieved by AAS instrumental analysis under optimal conditions. As a result of the analyzes, the maximum allowed toxicity limits for heavy metals in the soil have not been significantly exceeded, without affecting the health of the population, except for the vicinity of the ash pile (Order (OMAPPM Order 756 of 11/3/1997). References 1.NAMIESNIK, J., WARDENCKI, W., Acta Universitatis Chiniensis, Seria F Chemia 2, 2000, 3. 2.AYRAS,M., NISKAVARAA H., BOATYREV I., CHEKUSKIN V., PAVLOV V., REIMANN C., J.Geochem.Explor., 1997,58,269. 3.PALIMERI, F., NERI, R., BENCO, C., SERRACCA, L., J.Environ.Path.Toxicol.Oncol., 1997, 16, 175. 4. AUTORIZAŢIE INTEGRATĂ DE MEDIU NR. 11/05.07.2006, Revizuită 2010 5.CORDOŞ, E., FRENŢIU, T., POTRA, M., RUSU, A., FODOR, A., Analiza prin spectrometrie atomică, Ed. Institutului Naţional de Optoelectronică, Bucureşti, 1998. 6.PRICHARD, E., „Setting Standards in Analytical Science‖, Seminar RENAR, 2001. 7. Stabilirea impactului termocentralelor asupra solului SC ICMENERG SA C 4145/200, C3.083-60709/96 8.NICA-BADEA, D., MĂRUŢOIU, C., GOGOAŞĂ, I., BÎCĂ, MD, MĂRUŢOIU, OF, The biomonitoring of the thermoelectrically power station impact over the environment. the control of the degree of pollution by heavy metals in adjacent areas, Rev. Transcom, ISBN 978-80-554-0029-7, University Zilina, SLOVAC REPUBLIC, TITLUL A-8-TH EUROPEAN CONFERENCE OF RESEARCH WORKERS, 22nd to 24th June 2009. www.transcom2009.sk. 9. NICA-BADEA,D., MĂRUŢOIU, C., GOGOAŞĂ, I., MĂRUŢOIU, OF,, Le côntrole du degré de pollution avec des métaux du produits agroalimentaire végétale, Analele Universităţii ,,Constantin Brâncuşi‖ Tg-Jiu, No.2, vol.1/2007, p.271-276. 10. MĂRUŢOIU, C., GOGOAŞĂ, MĂRUŢOIU, OF., SORAN,ML., NICA-BADEA, D., Separation, identification and determination of some hard metals from silybum marianum L. ,,Metal Elements In enviroment, Medicine and Biology‖, Garban Zeno, Dragan Petru (Eds), Publishing House ,,Eurobit‖ Timişoara, vol. VII, 2006, p.241. 11.NICA BADEA D., Studiul privind influenţa emisiilor poluante provenite de la Termocentrala Turceni asupra poluării cu metale grele a solului şi a vegetaţiei, Raport Contract cercetare nr: 456/21.06.2010. 12. Ordinul OMAPPM 756 din 03.11.1997. 261 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X STUDY ON THE BATS SPECIES IN THE CAVES PROTECTED NATURAL OF NORTH WEST GORJ Lect. Irina Ramona PECINGINĂ „Constantin Brâncuşi” University of Tg-Jiu, [email protected] Abstract: The paper gives a brief description of the protected area North West Gorj ecological characteristics of caves, and the bats species present in holes and caves in the description of the protected area. Keywords: protected area, fauna, bats 1.Introduction The protected area North West Gorj ROSCI0129 covers an area of 86,958 hectares in 9 communes in Gorj county - Bumbesti-Jiu (7%), Godinesti (8%), Pades (23%), Pestisani (69% (86%), Schela (84%), Stanesti (67%), Tismana (82%) and Turcinesti (2%), as well as 3 localities in Hunedoara county: Lupeni (U% And Vulcan (<1%) and Baia de Arama (<1%) in Mehedinti County. Geographical coordinates: eastern longitude 23˚4'44 ", 45˚9'5" north latitude. Altitude: maximum -1940m, average - 835m, minimum -192m. (Figure 1). Fig. 1 Limit of Protected Natural Area North West Gorj 262 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 2. ECOLOGICAL CHARACTERISTICS OF CAVES Physical factors The most important environmental factors in caves are: obscurity, temperature, humidity, air currents, air composition, water content in gases, mineral salts and organic substances. The main source of energy that intervenes in the physical context of the caves is the solar radiation flux received by the surface of the carst (Figure 2). Fig. 2. The scheme of energy influences on a cave Trophic factors There are many possibilities in which organic matter produced externally is transported into fish, but, simplified it can be synthesized in the following scheme (Figure 3): 263 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Fig. 3. Schematic representation of ways in which alohtone trophic resources are transported inside caves 3. THE BATS SPECIES AND CAVES FROM NATURAL AREA PROTECTED NORTH WEST GORJ In the Protected Natural Area North of the West Gorj there are a large number of caves that are populated by various species of chiroptera. As for the grouping of individuals, this is done in clusters consisting of 8-12 individuals or isolated, leaving free spaces between them, or crowded. Rhinolophus ferrumequinum The Rhinolophidae family, the horseshoe bats, have fleshy excrescences on the nose to guide the ultrasound beams emitted through the nostrils. Nasal excretions are species of nature. During the rest, they wraps with their wings. (Figure 4) In the site, the population of Rhinolophus ferrumequinum is well represented and appears in Gura Văii Caves, Fuşteica Cave (fig.5), Cicarei Cave. 264 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Fig.4. Rhinolophus ferrumequinum Fig.5. Appearance from Fusteica Cave, Sohodol Gorges, Gorj County Myotis myotis (The common bat) Large waist, with the length of the forearm between 55,0 and 67,8 mm. It is characterized by a massive buttock and wide ears. (Fig. 6). Fig. 6. Myotis myotis In the site appears in the Fuşteica Cave and Gura Văii Cave. Rhinolophus hipposideros (Little horseshoe bat) It is the smallest species of horseshoe bats in Europe, having a small and delicate body (Figure 7). 265 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Fig. 7. Rhinolophus hipposideros Rhinolophus hipposideros is present in Coral Caves, Fuşteica Cave, Cicarea Cave. Myotis blythii Also known as the Blyth bat, it differs from the common bay by the smaller waist, the narrower widths of maximum 8-10 mm, shorter and sharper (Fig. 8). Fig. 8. Myotis blythii Myotis emarginatus Medium sized lilac with ear pavilion with distinct ridges on the edge external and 6-7 transversal folds (fig.9) 266 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Fig.9. Myotis emarginatus In the site appears in the Gura Văii Cave and the Bats Cave. Myotis capaccinii (Long-legged bat) It is a medium-sized species, has narrow ear pavilion with five horizontal outer folds. Very large legs with long and hard bristles. (Figure 10) In the site appears in the Pârgavu Cave and the Tismana Caves.(fig.11.) Fig. 10. Myotis capaccinii Fig.11 The cave entrance Tismana Miniopterus schreibersii (Bat with long wings) Medium-sized species, with very short, triangular nose and ears, short, rounded toe and long and sharp wings. (Figure 12) 267 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Fig. 12.Miniopterus schreibersii In the site appears in the Fuşteica Cave, Pârgavu Cave and Gura Văii Cave. Rhinolophus euryale It is a predominantly troglophilous species, which prefers the hectic and wooded areas, crossed by water courses, up to 1000 m altitude. Caves are the ideal shelter, especially for hibernation, but in the summer, maternal colonies can also be housed in housing bridges. Fig. 13. Rhinolophus mehelyi In the ROSCI0129 site, North West Gorj appears in Cioarei Cave and Gura Plaiului Cave. 4. CONCLUSIONS In the Protected Natural Area North of the West Gorj there are a large number of caves that are populated by various species of chiroptera. REFERENCES [1] The Bats Species Determiner (Chiroptera) of Romania, The Bats Protection Association of Romania, 2010 [2] Bats and Underground Housing Management- Methodological Guide, 2013 [3] ROSCI 0129 North West Gorj Management Plan *** - IUCN Red List of Threatened Species IUCN, 2006 268 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X FOOD BIOTECHNOLOGY - SUSTAINABLE DEVELOPMENT STRATEGY Lect. Irina Ramona PECINGINĂ, Assoc. Prof. Roxana Gabriela POPA „Constantin Brâncuşi‖ University of Tg-Jiu, [email protected] Abstract: Biotechnology is the integral application of biological and engineering sciences for the technological use of living organisms, biologically active acellular structures and molecular analogues for the production of goods and services.The role of biotechnology is very important in the food industry; this is a biotechnology because agro-food raw materials are biological products and therefore their conservation until consumption, fresh or industrialization involves the control of the enzymatic activity of the vegetal and animal tissues or of the microflora contamination. Keywords: food biotechnology, sustainable development 1.INTRODUCTION Considered as the last major technological revolution of the century, biotechnology is closely linked to issues of greatest interest in human development: the diagnosis and cure of diseases, food security and safety, and the protection of the environment. Biotechnology will become one of the most important weapons of the fight against hunger, malnutrition of the population. Biotechnology is a new science based on biology, the purpose of which is to use in the microorganisms or products derived therefrom cultures of plant and animal cells for the production of substances useful in agriculture and in the food, pharmaceutical, etc. industry the use of human activity. Applications of biotechnologies: • Agriculture (agricultural biotechnology) • Food, food biotechnologies are industrial processes for processing vegetables and fruits, milk and dairy products, meat • Medicine (veterinary medicine, public health, medicines, vaccines) • Energy generation (energy generation from waste) • Pollution control (methods and technologies for treatment) Biotechnology is the integral application of biological and engineering sciences for the technological use of living organisms, biologically active acellular structures and molecular analogues for the production of goods and services. The relationship between agriculture and food is becoming more and more obvious, because largely "civilization diseases" are attributed to a qualitatively inadequate nutrition, due to the excessive use of chemistry in intensive technologies and as such the product market, Bio "is the most sought after and appreciated. Organic farming is today a modern practice, with results based on scientific data that create a new concept of life, work and agriculture, with increased efficiency and can deliver products in line with demanding consumer requirements. (Figure 1.1.). 269 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Fig. 1. Food relationship - agriculture - biotechnology-health 2. ROLE OF FOOD BIOTECHNOLOGY Food biotechnologies include industrial processes for processing vegetables and fruits, milk and dairy products, and meat, generally targeting the fermenting aspects underlying them. The role of biotechnology is very important in the food industry; this is a biotechnology because agro-food raw materials are biological products and therefore their conservation until consumption, fresh or industrialization involves the control of the enzymatic activity of the vegetal and animal tissues or of the microflora contamination. Food biotechnology refers to the industrial processing of various raw materials with the help of microorganisms and their own enzymes or biological agents (microorganisms, enzymes) added to produce products or to improve technological processes. The role of biotechnology is overwhelming in the food industry. In fact, the food industry is a biotechnology because agri-food raw materials are biological products and therefore their conservation until consumption, fresh (in the case of fruits and vegetables) or until industrialization (all agrifood products) implies control of the enzymatic activity of the vegetal tissues and animal or microflora contaminated contamination. Enzymes for plant and animal tissues are essential in the transformation of agro-food products: the maturation of fruits and vegetables, cereals and flours, or various food products based on germinated cereals, cheese maturation, maturation of meat. Enzymes may also have a deleterious role with implications in modifying the sensory characteristics and nutritional value of agro-food raw materials to their thermal processing. Also, the role of microorganisms is crucial, some of which have harmful action, others play an essential role in producing foods due to their fermentative action: acidic dairy products, cheeses, beer, wine, spirits, bread, raw salami, fermented cereals and legume. The microorganisms interfere with the fermentation of vegetable products: cabbage, pickles, olives, cucumbers, cocoa, etc. 270 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 3. THE BENEFITS OF FOOD BIOTECHNOLOGIES IN THE CONTEXT OF SUSTAINABLE DEVELOPMENT Combating the global food crisis. According to the United Nations, food production will have to increase by 50 percent by 2030 to cover the needs of a growing population (Figure 3). Agricultural biotechnology has been shown to increase agricultural output by seven to ten times In some developing countries, which far exceeds the production capacities of traditional agriculture, and this has not remained unnoticed at the level of the global community. Fig. 3. Growth of the world population Improving the characteristics of the crops themselves to the selection of features that would benefit consumers' health. Soybeans are a good example in this respect, with over a dozen soybean varieties with benefits for human health to be launched shortly on the market. Beneficial features include replacing hydrogenated vegetable oil with alternative substances, reducing saturated fat and increasing omega 3 fatty acids. Consumers can be confident that agricultural biotechnology provides safety. These cultures have undergone numerous studies and have been declared safe by expert groups around the world. Over the 15 years since the biotech crops were introduced into the market, there has been no single proven case of affecting an ecosystem or a person's illness due to these foods. Real and meaningful benefits to farmers, consumers and the environment. Probably the most important impact of biotech crops on the environment has been determined by the adoption of unpolluted agriculture or agriculture with a minimal system of soil work. Herbicide-resistant crops, such as biotechnology soybeans, enable farmers to almost completely eliminate soil work, which contributes to improving soil health and 271 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X preservation, better water retention in soil, reducing soil erosion processes, and To reduce herbicide leakage. (figures 4 and 5) Fig. 4. Erosion of agricultural land worldwide Fig.5 Untreated US agriculture, soybean crops 272 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Developing a sustainable agricultural system as it allows for the production of a larger amount of food with less environmental impact than conventional agriculture. Increase in production and plantations. Biotech plants are resistant to pests, illness and adverse climatic conditions, which reduces unnecessary resource consumption and avoids the loss of millions of tons of agri-food products each year. Cost reduction due to reduced pesticide/herbicide use. The use of pesticides worldwide has fallen by more than 8.9 percent over the 14 years since the introduction of biotech crops, leading to the removal of 393 million kg (867 pounds) of active ingredients Underpin pesticides. Food safety through biotechnology. High yield crops developed by agricultural biotechnology can help achieve the goal of raising global food production by 50 percent by 2030 to meet the growing food demand expected by the United Nations. Rich crops of nutrients developed through agricultural biotechnology can meet the specific nutritional needs of consumers such as increasing the intake of Omega-3 fatty acids or reducing the consumption of saturated fats. These improved crops have been repeatedly declared safe by the most important regulatory bodies and scientific institutions around the world, which is why consumers can safely consume foods containing ingredients obtained through biotechnology. Reduction of greenhouse gases. Non-crop farming reduces the use of agricultural machinery on plantations, which leads to a significant reduction in greenhouse-gas emissions from agricultural equipment. Thus, crops obtained by agricultural biotechnology have led to a significant reduction in carbon dioxide (CO2) emissions in the environment. Soil maintenance and conservation. Thanks to crops resistant to biotechnical herbicides, farmers have been able to almost completely eliminate the work on the fields cultivated with them, resulting in significant health and soil conservation benefits, better water retention in the soil, thus reducing the process Soil erosion, as well as reducing herbicide spills. 4. CONCLUSIONS The role of biotechnology is very important in the food industry; this is a biotechnology because agro-food raw materials are biological products and therefore their conservation until consumption, fresh or industrialization involves the control of the enzymatic activity of the vegetal and animal tissues or of the microflora contamination. REFERENCES [1] Abbert Sasson., Biotechnologies and development, Technical Publishing House, 1992 [2] Banu, C., Biotechnologies in the food industry, Technical Publishing House Bucharest, 1987 [3] Bele N., et al., Nutrition and Health, Printech Publishing House, Bucharest, 2004 [4] Dan V., Food microbiology, Alma Ed., Galati, 2001 273 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X OXYGEN PRESSURE REGULATOR DESIGN AND ANALYSIS THROUGH FINITE ELEMENT MODELING Asterios KOSMARAS, International Hellenic University, Thermi, 57001 Thessaloniki, Greece, [email protected] Dr. Dimitrios TZETZIS, International Hellenic University, Thermi, 57001 Thessaloniki, Greece, [email protected] Abstract: Oxygen production centers produce oxygen in high pressure that needs to be defused. A regulator is designed and analyzed in the current paper for medical use in oxygen production centers. This study aims to design a new oxygen pressure regulator and perform an analysis using Finite Element Modeling in order to evaluate its working principle. In the design procedure,the main elements and the operating principles of a pressure regulator are taking into account. The regulator is designed and simulations take place in order to assessthe proposed design. Stress analysis results are presented for the main body of the regulator, as well as, flow analysis to determine some important flow characteristics in the inlet and outlet of the regulator. Keywords: Pressure Regulator, Finite Element Optimization, Stress Analysis, Flow Simulation 1. INTRODUCTION Originally, a pressure regulator is principally a device that is used to reduce higher pressures of gasses or liquids to a more usable lower pressure. Its main function is to reduce a pressure and to keep this pressure as constant as possible while the inlet flow may differ. A regulator‘s exactitude and prowess in performing its function is determined by the combination of the four basic regulator components, designed into a specific regulator unit (Loading Mechanism, Sensing Element, Control Element, and Relief Valve). These components have to be designed according to mathematical guidelines, so that they work together harmoniously to give the desired results. Calculations are not only necessary for the good order of the regulator but also for the endurance in high pressures and the flow characteristics of the mean. There is no much information published on pressure regulators due to the disquiet for leakage of proprietary knowledge. N.Zafera and G. R. Luecke(1)studied the stability of gas pressure regulators. Their research investigated the consolidation of a concrete implementation of pressure reducer system. Areas such as palpitation in regulatorsand possible design amendments are presented that expunge the not steady throb modes. T.i Kato et.al, (2)also investigated pressure regulators with high accuracy having quick response in pressure fluctuations. An effective adjustment of pneumatic palpitation isolation tables was presented. A regulator assembly was designed by the authors and the greatest characteristic of their design was the almost zero changes of pressure in the chamber that was detected by the transducer which changes the position of the servo valve, to preserve the initial pressure. In another study Kakulkaet. al.(3)studied a pressure regulator having a piston as a sensing mechanism. The sensingmechanism consisted of a conical poppet piston-valve that adjusted the flow of themean. The study dealt with the energetic results of limitative orifices and the upstream-downstream areas of the regulator. 274 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X However, the friction and pendulousnesseffects inside the areas of the body of the regulator, were not taken into accountin their research.B.G. Liptak(4)also reports on the changes in the exit pressure by creating fluctuates in the supplied flow. The author reports that any decrease in the fluctuations of the pressure abridges theconsistency of the output of the regulator. This had as result the regulator to make alot of noise when it worked with oscillatory pressure cycling. For stabilization, a larger downstream pipe is recommended. Also, the noise was eliminated by expunging the fluctuations of the flow routes and keeping theflow of the mean at speeds not exceeding supersonic speed. In this study a new pressure regulator is developed and designed. The static behavior and the flow characteristics were determine through finite elements. More precisely calculations were made for the stress contribution in the main body of the regulator and additionally a flow analysis in order to determine some important flow characteristics in the inlet and outlet of the regulator. 2. PRESENTATION OF THE DEVELOPED CONCEPT The pressure regulator that was developed was designed to be used in medical gas networks thus the primary flow mean is oxygen. The pressure regulator has been designed according to ISO: 9001 – ISO: 13485 for medical gas systems components. The developed model had to meet with some basic important requirements. The flow mean is oxygen in pressure of 200 bar, the outlet pressure has to be 10bar and the maximum flow at 200bar is 100m3/h. Figure 1 presents the pressure regulator made of brass that was developed with explanation of the important features. The Loading Mechanism denoted with (1) is a spring- load mechanism. The spring is controlled by a plastic spigot on the top of the dome of the regulator. In the dome designed a small hole for extra safety, in case that high pressure goes accidentally to low pressure chamber and brakes the diaphragm. The sensing element denoted with (2) is a diaphragm from elastomer material (Ethylene Propylene) for sensitivity to pressure changes, simplicity and low cost. The control element denoted with (3) is an overpressure protection system developed to avoid the possibility of overpressure of the inlet pressure chamber. For this reason, a tiny hole was designed in the bottom of the pressure regulator. The working principle is based on the fact that for a certain amount of pressure the control element will cause the poppet to fracture the orifice. By this movement of the poppet the down exit is released and the compressed gas is getting out to avoid failure of the regulator. The safety valve denoted as (4) in Figure 1 was designed to protects the regulator from possible failure. In the case the high-pressure passes from the high pressure chamber to the low pressure chamber the spring of the valve is compressed in order to relief the extra pressure. Also certain slots for manometers and transducers were designed and denoted as (5) in Figure 1. 275 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Fig. 1 Intersections showing internaly the design of the pressure reducer 3. DESIGN SIMULATION 3.1 Stress analysis The stress analysis was performedusing finite element modeling. For the static analysis the internal chamber of the body of the regulator is set on high pressure. The purpose of the analysis was to show if the regulator can withstand ahigh gas pressure. The maximum pressure that is supposed to be applied in the regulator is 200 bar. For safety reasons the regulator was simulated under a pressure of 300 bar.The material that have been used for the analysis was brass having tensile strength of 0.478 N/m2, yield strength 0.239N/m2, elastic modulus 1010N/m2, shear modulus 34∙109N/m2 and Poisson‘s ratio 0.33. The boundary conditions that have been used for the analysis are shown in Figure 2. For the analysis 21747 nodes and 13047 elements have been used. The results have shown that the maximum stress that is applied inside the regulator is 1.07N/m2 which much lower than the yield strength of the material and the maximum displacement 0.012 mm. Figure 3 shown the stress and strain contours of the analysis. It should be noted that the applied pressure in the study was already higher than the pressure, thereby the results are somewhat conservative. 276 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X a b c Fig. 2 Boundary conditions used for the stress analysis of the pressure reducer with a)Fixes Inlet and outlet connectionsb) Botom is fixed with screws c) Chamber under high pressure (300 bar) a b c Fig. 3 Stress contours of the pressure regulator showing:a) stress distribution, b) displacement distribution, c) strain distribution 277 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 3.2 Flow Simulation In this section the flow simulations are presented.For the flow simulation study, the pressure regulator simulated with the valve fullyopened in order to see the maximum outlet flow rate through the designed orifices. The properties measured, as depicted in Table I, were the average flowrate in the outlet, the average outlet total pressure and the average temperature in thedecompressionchamber. Table I. The properties measured in the flow simulation analysis. Unit Value AvValue MinValue MaxValue VolumeFlowRate [m3/s] 0,02 0,02 0,02 0,02 AvTotalPressure [Pa] 1042610,71 1067482,10 958725,13 1155812,86 AvTemperature (Fluid) [K] 239,15 236,77 231,99 240,43 The results show that the values obtained from the analysis were within the limits of the regulations. The flow trajectories are depicted in Figure 4(a). The pressure remains high in the high-pressure chamber and then passes through the control element that decreases the pressure with an adiabatic process. Then the oxygen expands in the low-pressure chamber that remains low until the gas exits the regulator. Figure 4(b) shows the temperature distribution inside the pressure regulator. a b c Pressure Pressure droparea droparea Fig. 4 Stress contours of the pressure regulator showing: a)Flow trajectories b) Temperature distribution, c) Pressure distribution 278 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X The temperature is about 293K when the oxygen inserts the regulator. Later the temperature decrease rapidly because of adiabatic expansion of the oxygen and then approaches again the room temperature. The lowest temperature is in the area that the pressure drop take place and it is about 217 K. Figure 4(c) presents the pressure distribution inside the regulator. The oxygen enters the pressure regulator in high pressure 200 bar. Pressure drop is occurred in the pressure reduction area. The oxygen exits the regulator having a 10 bar pressure. 4. CONCLUSIONS The stress analysis have shown that the maximum stress that is applied in the chamber was 1.07N/m2when the maximum yield strength of the material is almost 2 times higher. The displacement was also very small. Inflow simulation analysis of the pressure regulator have shown that the proposed design seems capable to feed the system after the regulator with about 100m3/h volumetric flow with the shutter fully opened, which is a very satisfying flow rate for medical uses. The lowest temperature is about 217 K which is a normal value because of the adiabatic expansion that take place inside the pressure drop area. Furthermore, the flow diagrams show how the oxygen is diffused inside the regulator and this gives to the reader a more realistic and comprehensible view of how a pressure regulator works.The flow simulation analysis show a complicated flow distribution of the flow inside the pressure regulator. This distribution changes by alterationsof the shape of the internal orifices. Future work will investigate how the shape changes affect the important characteristics of the regulator such as the stability of the regulator in pressure changes and the external flowrate. REFERENCES 1. N.Zafera, G. Lueckeb, Stability of Gas Pressure Regulators, Applied Mathematical Modelling, 2008, pp. 61-82 2. T. Kato, K. Kawashima, T. Funakic, K. Tadano, T. Kagawa,A New High Precision Quick Response Pressure Regulator for Active Control of Pneumatic Vibration Isolation Tables, Precision Engineering, 2010, pp 43–48 3. D.J. Kukulka, A. Benzoni, J.C. Mallendorf, Digital Simulation of a Pneumatic Pressure Regulator, Simulation 1994, pp 252–266 4. G. Liptak, Instrument Engineers' Handbook, (Volume 2) Third Edition: Process Control, CRC Press, 1995 279 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X ANALYTICAL DETERMINATION OF CONDITIONS FOR PRODUCTIVITY IMPROVEMENT OF DIAMOND GRINDING Prof. PhD. Eng. Feodor NOVIKOV1, General Director PhD. Vladimir POLYANSKY2, Sen. Staff Scientist Yury GUTSALENKO3, Scientist Ass Vladislav IVKIN3 1Simon Kuznets Kharkov Nat. Univ. of Economics, [email protected] 2Empire of Metals Ltd., [email protected] 3Nat. Tech. Univ. ―Kharkov Polytech. Inst.‖, [email protected] Kharkov, Ukraine Abstract: The analytical dependences for definition of processing productivity when grinding by diamond wheels on metal bonds with the accounting of linear wear of the grain which is the most acting over the level of bond are given on the basis of probability-theoretic approach.. Conditions of electroerosive dressing with providing the optimum cutting relief of diamond wheel are defined. A high-performance process of longitudinal external cylindrical diamond grinding of fast-cutting and hard-alloy multiedge tools (mills, reamers, core drills, etc.) is developed with high quality of processing and renting allowance to 1,2 mm per side in one pass. Keywords: diamond grinding, a diamond wheel on a metal bond, processing productivity, quality of processing, the optimum cutting relief. 1. INTRODUCTION Diamond grinding became an important factor of scientific and technical progress in mechanical engineering when machining the details made of materials with the increased physic-mechanical properties. First of all it belongs to processing of metal and nonmetallic materials of the increased hardness (hard alloys, wearproof surfacing and coverings, diamonds, ceramics and ferrite, technical glass, crystal, etc.). For their processing Diamond wheels on tear-proof metal bonds working in the mode of continuous or periodic electroerosive (electrochemical) dressing are used for their processing with providing the high rates of quality and productivity of processing [1-3]. At the same time it is necessary to approach to the choice of optimum conditions of processing with scientifically reasonably effective use potential opportunities of these wheels. Therefore the task of research consist of analytically determination of the conditions for high productivities of diamond grinding and also to develop the method of deep diamond grinding of hard-alloy and fast-cutting multiedge tools. 2. ANALYTICAL RESEARCH In general the depth of insertion of the cutting grain into the processed material for microcutting (H ) is determined by the hardness (by Vickers) of the processed material (HV ) and radial force Р which acting on the cutting grain. Then, for a conical model of grain у1 with an angle 2 at its top [1]: P H y1 . (1) tg 2 HV 280 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X As follows from the dependence (1), the greater the hardness of the processed material HV and less strength Ру1 , the lower the depth of grain introduction H. Consequently, when grinding hard-to-work materials, the depth H will be small. Coefficient 1 H / X , which determines the degree of protrusion of the grain over the level of a bond of a diamond weel and changes within the limits 0 ... 1, under the condition b H also will be small (b is the maximum height of the protrusion of the vertices of the grains over the level of the bond of the wheel, m; Х is the grain size of the wheel, m). However, it does not follow from this that the decrease in the productivity of processing Q determined by the dependence which obtained on the basis of the theoretical-probabilistic approach for grinding [1]: S tg m V ' 1 3 1 2 Q det , (2) 600 where S is the cross-sectional area of the straight-line workpiece (plate) with moving at a constant speed V' in normal to the working surface of the diamond wheel, m2 (Fig. 1); det x/ Н is the dimensionless coefficient taking into account the degree of blunting of the grains, varies within the range 0 ... 1 ( 0 for sharp grain, 1 for blunted grain); х - linear wear value for the diamond grain with maximum protruding above the level of the bond of the wheel, m; H - conditional maximum depth of introduction of the processed material into the working surface of the wheel measured from the nominally (without wear) maximum protruding grain, m. V 3 det х H Hmax b 1 2 Vс Fig. 1. Calculation scheme of the parameters of the grinding process: 1 - level of the bond; 2 - cutting grain; 3 - processed sample. This is due to the fact that, simultaneously with the decrease in the maximum height protrusion of grain above the level of a wheel bond b H , less coefficient 9Vdet 1 2 ; (3) tg k Vc b 281 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X this makes it possible to compensate of decrease in processing capacity Q with considering the reduction of the dimensionless coefficient (1 ). In (3): Vdet - speed of movement the processed sample along the normal to the working surface of the wheel, m/s; k - surface concentration of grain of a wheel, pcs/m2. It is established that the main condition for increasing productivity processing Q when grinding high hardness materials is to maintain the diamond wheel of "sharp" cutting relief ( 0). This is achieved by work the diamond wheel in self-sharpening mode by applying relatively resistant organic or ceramic bonds, or the work of a diamond wheel on metal bonds in the regime of its continuous erosion dressing. It is known when the grain size of the diamond wheel increases then the strength of the grain on crushing (determined by a destructive load equal to P1 ) increases too by dependence P1 A , where and 1 are constants [2]. Then the coefficient 1 H / X is determined with account the dependence (1): 1 1 . (4) X 10,5 tg 2 HV As can be seen from (4) the coefficient 1 the larger the smaller the graininess of the wheel X and more parameter , which determines the relative strength of grains of various marks of diamonds. Therefore, according to the dependence (2), it is necessary application of fine-grained diamond wheels with increased strength of diamond grains to increase the processing efficiency Q when processing materials of high hardness. The granularity of the diamond wheel should be chosen inversely proportional to the hardness of the processed material taking into account that the parameters X and HV (4) with approximately the same degree (equal to 0.5). According to the dependence (4), reducing the graininess of a wheel leads to increase in the 1 , i. e. increase the degree of protrusion of grain over the level of the bond of the wheel and the reduction of the part of the grain located in the bond of the wheel. Therefore, the strength of grain retention will decrease and it is necessary use more strong metal bonds of a diamond wheel to increase it. The efficient life of diamond wheels is determined by the range of variation of the ratio 0 ... 1 1. The higher the value 1 , the higher the stability of the wheel. Increase value 1 requires an increase in the parameter H, according to 9b Vdet 3 H 2 , (5) tg k Vc 1 and coefficient 1 , according to the dependence (4). Therefore, to increase the diamond wheel durability can be due to an increase in the height of the protrusion of grains above the bond level, the use of stronger metal bonds and methods of opening of diamond layer of the wheel, for example, EDM. 282 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X In the general case, for a more correct presentation of technological possibilities of diamond grinding in the design scheme shown in fig. 1, the parameter b should be considered as the sum of two terms: b H , where is the height of the intergranular space of the wheel, occupied by chips and other processing products, determined by the dependence: 0 , where: is the coefficient, taking into account the degree of filling of the intergrain space of the wheel with the chips ( 1); 0 is the thickness of the conditional layer of the "melted" processed material, which is formed by one rotation of the wheel, m. The following relationships are valid for cylindrical longitudinal grinding [1]: St Q B Vdet t Vdet t 0 , (6) B Vc B Vc B Vc where St Q / Vc - instantaneous total cutting section from all simultaneously working wheel grains, m2; B – is the width of the circle, m. Obviously, the smaller the parameter , the greater the processing capacity Q when grinding. Consequently, ideally, it is necessary to strive to fulfill two conditions: 1; b H . According to the theoretical studies carried out for ordinary diamond grinding of carbide details, coefficient varies from 100 to 1000 and more. Therefore, its decrease, for example, in 10 times, will allow the same number of times to improve a processing performance. When diamond grinding of various steel, titanium alloys and other relatively plastic materials, the coefficient is yet more, and the effect of processing from decreasing for such materials there may be more higher. It can be achieved a significant reduction in the coefficient by application of various methods of vibratory and ultrasonic chip shredding improving its placement on the working surface of the diamond wheel. The diamond electro-erosion grinding [1] (or diamond-spark grinding in the terminology of the organization-developer [3]) has significantly more technological opportunities among others combined grinding methods, providing dissolution, reflow or the combustion of chips in the cutting zone. It can be approximated the coefficient value to the value =1 at optimum conditions of diamond electro-erosive grinding and turn the cutting relief of diamond wheel into a fully active one, in which the complete removal (cut) of the metal in a cutting zone is being processed at the level of the bond of the wheel. Thus a developed cutting relief and high resistance of the diamond wheel at the maximum realization of it potential provides with the correct assignment of mechanical and electrical modes of diamond electro-erosion grinding due to the effective use of the energy of electrical discharges in the impact on a bond of diamond wheel and chips. In view of the above it is important to carry out an analysis of the external cylindrical diamond grinding (Fig. 1) for the conditions 1 and b H which can be realized due to the methodology and practice of diamond electro-erosion grinding [4]. In this case dependences for parameters H, and Q have the forms [5]: 283 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 9b V 2t 3 det H 2 ; (7) tg k Vc 1 9 Vdet 2t 1 2 ; (8) tg k Vc b 2 2 4 2 2 2 S0 tg k b Vc 1 Q S0 Vdet t , (9) 162 Vdet where Vdet - speed of the workpiece, m/s; Vdet Vdet 2t ; t - depth of grinding, m; S0 - 1 1 longitudinal feed, m/s; ; Rc , Rdet - the radius of the wheel and the detail, m. Rc Rdet According with the dependence (9) an increase in hardness of the processed material HV leads to a decrease in the parameter b H and coefficient 1 , and consequently in the processing capacity Q. In accordance with the dependence (8) it is possible to achieve the increasing of processing capacity Q by decrease a coefficient at realizing regime self- sharpening of a diamond wheel on an organic or ceramic bond or regime of autonomous dressing of the diamond wheel on metal bond. Obviously, the approach with the choice of the optimal bond for providing the work of diamond wheel in self-sharpening mode when b H is more universal. An important condition for improving grinding performance of hard-to-work materials should also be considered a reduction in speed the details Vdet and increasing the longitudinal feed S0 , depending on 9 2 Vdet Q 1 2 , (10) tg k Vc b S0 in connection with the decrease in the parameter b, saving the parameters and Q constant. The depth t must then increase from the Q S0 Vdet t const . Hence, with increasing the hardness of the processed material to effectively use the scheme deep grinding with a relatively low speed of the workpiece Vдет at longitudinal feed S0 B (where B is the height of the wheel, m). On this basis it was developed a high-productivity process of longitudinal external cylindrical diamond grinding of fast-cutting and hard-alloy multiedge tools (mills, reamers, core drills, etc.) is developed with high quality of processing and renting allowance to 1,2 mm per side in one pass. Grinding according to the proposed scheme is carried out with B1 0,9 B and Vdet =1.5 m/min, which allows to increase the processing capacity Q in 1,5 ... 2 times at economically reasonable costs for the consumption of diamond material unlike existing processes of deep grinding where the longitudinal feed per revolution of the workpiece B1 not exceeds 0.1 of 284 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X the width of the wheel B and the rotation speed of the workpiece Vdet is 20 ... 30 м/min. The effectiveness of this method of grinding has become possible thanks to specially developed principles for assigning the parameters of the cutting mode according to which the search for optimal grinding conditions should be from the condition of ensuring the complete removal of metal at the level of allowable (strength) thickness of the cut when the specific consumption of diamond takes minimum for any relief of the wheel, size and concentration of it grains. The performed analytical studies have shown that for determining the optimum grinding mode is sufficient to know the permissible (strength) cutting thickness Hmax , which is established by calculation and experimentation: tg k V H 3 V кр max . (11) det 9b 2t Analytical dependency for determining Hmax , 9b 2 V Q 6 det Hmax 3 , (12) tg k Vc B proposed for comparison of the considered above sheme and conventional practice of deep grinding proposed for comparison of the proposed scheme and conventional practice of deep grinding. Operating with dependency (12) confirms the efficiency of reducing the speed of the workpiece Vdet from point of view increasing processing capacity Q, and, consequently, the advantage of the scheme with longitudinal feed B1 approximately equal to the width of the wheel B at conditions of increased depths of grinding. It is possible to increase the processing capacity Q from (9) by reduce the speed of the part V while saving the values and Q in dependence (10) for solution of technological det tasks of grinding applied to materials with a high hardness when a value of the maximum height of protrusion of the tops of grains above the level of diamond bonds b is small. Decrease admits increase in grinding depth t from condition Q const . The greatest effect is achieved under the condition t Rdet . This condition can be realized by abrasive forming of deep cutouts, grinding of deep grooves, abrasive sawing, as well as with flat grinding by face wheel with rotating machine table when parameters t Rdet and S0 which enter into the dependence (10) are considered respectively as the grinding width and the depth of grinding. 3. CONCLUSION The analytical dependences for definition of processing productivity when grinding by diamond wheels on metal bonds with the accounting of linear wear of the grain which is the most acting over the level of bond received on the basis of probability-theoretic approach are marked and discussed. 285 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Received theoretical results are tested in the developments and applications of stable processes of high-performance diamond grinding with electro-physical stimulation of processing and others [4, 6]. Analysis and practice of realizations of theoretical research results develop experience of work-out of diamond-spark grinding technique, tools and technologies in the Kharkov Scientific School of Physics of Cutting and indicate the prospects for further research in this direction. REFERENCES [1] Physico-mathematical theory of the processes of material‘s treatment and engineering technology. Ed. by F. V. Novikov and A. V. Yakimov. In 10 vols. Vol. 1: Mechanics of material cutting, Odessa, Odessa Nat. Polytech. Univ., 2002, 580 p. – In Russian. [2] Lavrinenko, V. I., and N. V. Novikov. Superhard abrasive materials in machining. Kiev, ІSМ of NAS of Ukraine, 2013, 456 с. – In Ukrainian. [3] Gutsalenko, Yu. G. Diamond-spark grinding: an overview of the Fortieth Anniversary of the development of the Kharkov Scientific School of Physics of Cutting. Physical and Computer Technologies. Proceedings of the 18th International Scientific and Practical Conference, December 5-6, 2012, Kharkov. SE KhМP ―FED‖, 2012, pp. 79-88. – In Russian. [4] Gutsalenko, Yu. G. Diamond-spark grinding of high functionality materials [Online resource]. Kharkov, Cursor, NPU «KhPІ», 2016, 272 p. [3,75 Мб], access code: http://web.kpi.kharkov.ua/cutting/dsghfm-monograph.pdf. – In Russian. [5] Yakimov, A. V., F. V. Novikov, G. V. Novikov, B. S. Serov, and A. A. Yakimov. Theoretical bases of material‟s cutting and grinding. Odessa, Odessa Nat. Polytech. Univ., 1999, 450 p. – In Russian. [6] Novikov, F. V., and I. A. Ryabenkov. Finish machining processing details. Kharkov, Simon Kuznets Kharkov Nat. Univ. of Economics, 2016, 270 p. – In Ukrainian. 286 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X GEOMETRY MODELING OF GEAR AND CHAIN DRIVE WITH EVOLUTE PROFILE AND RESEARCH OF ITS CONTACT STRESS Sen. Lecturer Roman PROTASOV1, Sen. Lecturer Sergey ANDRIENKO2, Prof. PhD. Alexander USTINENKO1, Sen. Lecturer PhD. Alexey BONDARENKO1, Sen. Lecturer PhD. Nicholay MATUSHENKO1* 1Nat. Tech. Univ. ―Kharkov Polytech. Inst.‖, *[email protected] 2Kharkov Nat. Automobile and Highway Univ., [email protected] Kharkov, Ukraine Abstract: Evolute gearing is realized in a family of teeth profiles for gears and chain drives with convex-concave contact. The main criterion of loading capacity for gear is contact strength, for chain drive – tooth wear. Both indicators depend on the level of contact stress. Therefore, the aim of this work is to determine the contact stress in the evolute gearing. Calculations of contact stress are based on the Hertz formula and the finite element method. The analysis and comparison of results for different evolute profiles is carried out. Keywords: evolute gearing, gear, chain drive, convex-concave contact, contact stress, finite element method. 1. INTRODUCTION The main cause of failure in enclosed gears is pitting. In open gears and some chain drives (for example, agricultural and mining machines, bushing chains without rollers, sprockets of tracked vehicles) abrasive wear of the teeth surfaces takes place. As known, pitting and abrasive wear of teeth are depend on the intensity of contact stress in the gearing. In turn, the contact stress is decreased by increasing the reduced radius of curvature ρH in the gearing. It can be increased by the use of teeth with convex-concave contact. Therefore, the development and research of new gearing for gear and chain drives, providing convex-concave contact, an actual task of modern engineering. One promising solution to this problem is the use of so-called evolute gearing. This is a family of profiles for gear and chain drives with convex-concave contact. It created by Ukrainian scientist A.I. Pavlov [1] and based on Bobillier construction [2]. Replacement the gearing by an equivalent four-link hinge-lever mechanism is main idea of this construction. Changing the geometric dimensions of the mechanism can be synthesized the gearing with a variety of geometric and kinematic characteristics. Main characteristics are the reduced radius of curvature ρH and the relative sliding velocity λ. The value of λ has major impact on the wear of teeth profiles. 2. MATERIAL AND METHODOLOGY 2.1. Geometry synthesis of evolute gearing As a result of the Bobillier construction for gear or chain drive, we obtain the ordinary differential equation (ODE) of 2nd order. It describes the movement of the contact point between the teeth (or tooth and bush chain for chain drive). This equation has the next form for the basic rack tooth of gear [1]: 287 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 2 y0 (1 y0 ) y0 . (1) ky0 x0 For the sprocket tooth of chain drive [3]: y 1 y2 r f k1 Ay k y 0 , A ; (2) 2 xr0 f k1 Ay yr0kf 2 r0 k f k - x0, y0 are the coordinates of the tooth profile. The centre of the coordinate system coincides with the pitch point P. Axis x0 is tangent to the pitch circle by radius r0; - f is the coefficient of sliding friction in the gearing, - k=h·sinα0 is the so-called variation coefficient of gearing [1]. This is one of the most important parameters for evolute gearing. It allows controlling the geometric characteristics of the synthesized gearing, - h is the distance between pitch point and the rotation centre of the connecting rod replacement mechanism, - α0 is pressure angle at the pitch point. Two approach to solve these ODEs are proposed: 1. The approximate solution in the form of a polynomial [1, 3] using the program complex Vissim: 3 n y0 (x0 ) C1x0 C2 x0 ... Cn x0 . (3) 2. Numerical solution [3] by the Runge-Kutta method in the software-system MathCAD with the built-in function Rkadapt: S Rkadapt(y, xstart, xend ,n,F) ; (4) - y is either a vector of k real initial values, where k is the number of unknowns, - xstart and xend are real, scalar endpoints of the interval over which the solution to the ODE is evaluated, - n is the integer number of discretization intervals used to interpolate the solution function, - F is a vector function of the right-hand side of the system. Additionally for evolute gearing, the solution (3) for the basic rack tooth is transformed to an equation of gear tooth profile [4]. For its use in a method of profile normal [2]. Fig. 1 shows examples of synthesized teeth profiles for gear [4] and chain drive [3]. The profiles are constructed in the coordinates system x, y. Center of coordinates system coincides with the rotation center of gear or sprocket. For chain drive, y-axis coincides with the tooth symmetry axis. For gear drive, y-axis coincides with the symmetry axis of tooth space. 288 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X a) b) Fig. 1. Synthesized teeth profiles: a) the conjugate gear pair teeth [4] (m=4mm, α0=15°, z1=20, z2=40, k=–5), b) sprocket tooth [3] (pitch chain t=25.4mm, z=20, k=–5) 2.2. Determination of contact stress in gearing on H. Hertz formula We use the formula to calculate the contact stress as follows [5]: Fn EH H 0.418 ; (5) bw H - Fn is the normal tooth force, - EH 2E1 E2 E1 E2 is the reduced modulus of elasticity for the materials of contacting bodies (E1, E2 are modulus of elasticity for pinion and gear), - H 1 2 2 1 is the reduced radius of curvature in the contact between two surfaces (ρ1, ρ2 are radius of tooth profile curvature for pinion and gear), "+" sign for the biconvex contact, "–" for the convex-concave contact, - bw is the working width of the tooth. The method of determining the radius of profile curvature depends on the method of solving the ODE (1) or (2). In the case of finding the profile in the form of the polynomial (3), radius of curvature can be determined using well-known formulas of differential geometry [6]. If the profile found by numerically (4), then it is preferable to find radius of curvature by a numerical method of "three points" [7]. 2.3. Modelling of contact interaction by finite element method CAD-system Autodesk Inventor has been applied to construct parametric models of gear pair and pair of sprocket-bushing. FEM-system – add-in Autodesk Inventor – Nastran In- CAD [8], solved the contact problem. Tooth profile built on 200 points in the xy plane with an accuracy of 7 decimal places. A high degree of accuracy is necessary because the profile equation is given by a polynomial function. The low accuracy in the calculation of the coordinates will manifest itself in the variable curvature of the curve over a section of several points. The result of low accuracy is shown in Fig. 2. 289 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X a) b) Fig. 2. Low accuracy in curve: a) in 3D-model, b) in relative units of curvature Profile points were placed in the working plane with a tool Import Point. Then, the spline was construct on these points by the parameter Curve. Use the tool Curvature has been defined curvature of obtained profile. Graph of the changing curvature of profile built. The obtained data were compared with numerical calculation for the curvature of tooth profile. Analysis of the results showed sufficient accuracy for profiles in Autodesk Inventor program. In Fig. 3a shows curvature of tooth profile, obtained by numerical method and Fig. 3b displaying curvature in the CAD-system Autodesk Inventor. a) b) Fig. 3. Curvature profile evolute: a) numerical method, b) Autodesk Inventor program The finite element analysis has been performed for a model of two tooth sectors. In the case of a chain drive, the sprocket sector and bushing of chain used. Sector consists of three teeth. The width of this sector equal to half of the tooth working width. Symmetry with respect to the median plane of the wheel is define in the CAE-system. Also has been removed chamfers and fillets. At the contact zone of teeth or tooth sprocket with the bushing has been created an area in the form a half-cylinder with a diameter of 1.5mm. It is necessary to specify the size of the finite element (FE), comparable to the size of the contact patch. The creation of this numerical model allows efficient and economical use of resources and time of your computer. At the same time, such a model will not worsen the accuracy of the result. 290 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Initial data for calculation in the program Nastran In-CAD: friction coefficient for the contacting bodies 0.1, material – steel with characteristics: Poisson's ratio ν=0.3, modulus of elasticity 11 E1=E2=2.1·10 Pa, the type of finite element – "tetrahedrons", the creation of torque gear or sprocket – around the axis z, introduction of the boundary conditions for gear and bushing of chain drive – complete fixation. As a result, creation of the FE gears model obtained 295 thousand knots and 198 thousand elements, from chain gears these values were 61 thousand knots and 36 thousand elements. Fig. 4a shows a general view and FE models, Fig. 4b – area in the contact of teeth with a fine mesh. a) b) Fig. 4. Finite Element model gear drive: a) general view, b) area at the contact place From chain drive similar result show a Fig. 5a and Fig. 5b. a) b) Fig. 5. Finite Element model chain drive: a) general view, b) area at the contact place 291 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X As a result of the FE analysis, distribution of contact stress shown in Fig. 6 has been obtained. a) b) Fig. 6. Contact stress: a) contact patch at half the tooth length, b) edge effects The FE analysis takes into account the edge effect, so in the case of equal tooth width for gear pair contact pressure at the ends of the teeth are reduced. As seen in Fig. 4b, the size of FE in the contact area satisfies the condition – 4 element to the width of the contact patch. It is sufficient for solving the contact task. eqv In addition, the equivalent von Mises stress on the contact surface ( H 0.4 H ) and in eqv depth ( Hd 0.56 H ) has been obtained. Distribution of von Mises equivalent stress is shown in Fig. 7a. The concentration of depth stress is shown in Fig. 7b. It displays Mises stress in the cross section of the tooth (in this case – the middle cross section). The possibility of a detailed analysis for the stress distribution is an advantage in the calculation using the FEM. Analysis of Fig. 7a and 7b display typical stress concentrators in the body of the tooth near the contact patch. In Fig. 8a displays von Mises stress for chain drive, and Fig. 8b – stress in depth tooth and chain roller. a) b) a) b) Fig. 7. Equivalent stress in evolute gear: Fig. 8. Equivalent stress in evolute chain drive: a) von Mises, b) von Mises in depth tooth a) von Mises, b) von Mises in depth tooth 3. CONCLUSION 1. Evolute gearing allows to improve the loading capacity of cylindrical gears and chain drives due to the convex-concave contact. 2. Evolute gearing profile have been synthesized in two ways: in the form of a polynomial and numerically by the Runge-Kutta method. 3. Parametric models of gear pair and sprocket-bushing pair have been built. The method of computer model modification for import into CAE-system was improved. The main need for this was to save computer resources for the FEM calculation. 292 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 4. The analysis of contact stress in the gear and chain drive has been carried out. Contact stress according to Hertz formula, contact stress and von Mises equivalent stress using FEM have been determined. 5. The resulted technique of construction 3D-model of gear and chain drives and the analysis of its stress-strain state have shown high accuracy of the results comparable to those obtained analytically and in numerical experiments. The main need was to save time and computing resources in the analysis of new drives with an evolute gearing. REFERENCES [1] Pavlov, A. I., 2005. The Modern Theory of Gearing. Kharkov, KhNADU, 100 p. – In Russian. [2] Litvin, F. L., 1968. The Theory of Gearing. Moskow, Nauka, 584 p. – In Russian. [3] Andrienko, S. V., А. V. Ustinenko, and R. V. Protasov, 2014. Numerical Solution to the Synthesis of Sprocket Tooth Profile for Bush-roller Chain Drive. In: Bulletin of NTU "KhPI". Series: Problems of mechanical drive. Kharkov, NTU "KhPI", No. 31(1074), pp. 10–15. [4] Protasov, R. V., and А. V. Ustinenko, 2010. Construction of Teeth Working Profiles for the Evolute Gears. In: Bulletin of NTU "KhPI". Series: Science of machines and CAD system. Kharkov, NTU "KhPI", No. 10, pp. 124–128. – In Russian. [5] Koval'skij, B. S., 1967. Calculation of Details for Local Compression. Kharkov, HVKIU, 222 p. – In Russian. [6] Smirnov, V. I., 1974. Course of Higher Mathematics. In 5 vols. Vol. 1. Moskow, Nauka, 479 p. – In Russian. [7] Korn, G. A., and T. M. Korn, 1968. Mathematical Handbook for Scientists and Engineers. 2nd ed. New York, McGraw-Hill, 1130 p. [8] Autodesk® Nastran® In-CAD 2016 Subscription Advantage Pack (SAP) [online]. Available via: https://knowledge.autodesk.com/sites/default/files/file_downloads/User's_Guide_Autodes k_Nastran_In-CAD_2016_SAP_ENU.pdf. 293 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X ANALYTICAL DETERMINATION OF CONDITIONS FOR SURFACE ROUGHNESS REDUCTION IN DIAMOND GRINDING Sen. Lecturer PhD. Igor RYABENKOV1, Sen. Staff Scientist Yury GUTSALENKO2, Prof. PhD. Eng. Cătălin IANCU3, Prof. PhD. Eng. Feodor NOVIKOV4 1Petro Vasylenko Kharkоv Nat. Tech. Univ. of Agriculture, [email protected] 2Nat. Tech. Univ. ―Kharkov Polytech. Inst.‖, [email protected] 3 C-tin Brâncuşi Univ. of Tg-Jiu, [email protected] 4Simon Kuznets Kharkov Nat. Univ. of Economics, [email protected] Kharkov, Ukraine Abstract: The article contains analytical dependences for determination of main parameters of surface roughness in diamond grinding. It is shown that the accounting values of linear wear of grains range matches the theory and practice of grinding. This indicates the effectiveness of reducing surface roughness by adjusting the values of linear wear of grains range. Lack of dependency of surface roughness parameters calculated depth of sanding attests to the effectiveness of deep grinding, which allows you to combine the operations of the preliminary and final grinding in one operation, while providing increased in 10 ... 100 times the processing performance and execution of technological requirements on quality of processing. Keywords: diamond wheel, deep grinding, surface roughness, grain linear wear, processing performance, treatment quality. 1. INTRODUCTION Application of diamond grinding has opened the new technological features of high- quality processing of machine parts made of composite materials. This is connected with reduced power and thermal tension of grinding process and exclusion of forming of burn marks, cracks and other temperature defects on processed surfaces due to the unique physical and mechanical properties of synthetic diamond [1-2]. Along with this, the process of diamond grinding leads to a decrease in microroughnesses on the machined surfaces, that positively affects the operational properties of the treated parts [3]. It is essential to know the functional relationships of the main parameters of surface roughness with grinding mode, characteristics of diamond wheel and other conditions of processing for its regulating from the point of view of a given surface roughness. In this work has been provided a simplified kinematic and refined physical model of diamond grinding. Their usage allows to identify and justify the most perspective directions of decrease surface roughness in diamond grinding by calculation without complex experiments. 2. ANALYTICAL RESEARCH Кinematic model of the grinding process based on analytical solution for description of the boundary of the complete dispersion of material by cutting grains in the cutting zone along the arc of contact wheel with workpiece has been developed for the solution of the assigned task. According to Fig. 1, the boundary is been drawn along the tops of machined material roughness and has a complex configuration, links wheel and workpiece surfaces as well as defines the position of the conditional (probabilistic) cutting surface in grinding as in edge 294 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X cutting processing. Characteristic points of a boundary are the basis for the calculating of the physical and technological parameters of grinding (the maximum cutoff thickness, roughness parameters, the actual length of the arc of wheel contact with workpiece, etc.) that allows to describe patterns of process analytically and quite unambiguously from common positions and in all possible cut depth range including multi-pass and deep grinding. 1 О2 Rc 2 H Vc Hmax t b t 4 А T1 3 5 О Rmax Rdet Vdet О1 Fig. 1. Estimated scheme of parameters of external cylindrical grinding [4]: 1 – wheel; 2 – cutting grains of wheel; 3 – layer of machined surface residual roughness; 4 – line of complete removal of material; 5 – Elementary cylindrical casings of allowance. As it follows from the Fig. 1, the essence of kinematic models is an establishing of the patterns of material removal and surface fofming along the arc of wheel contact with workpiece. The need to develop such a model due to the fact that the known settlement schemes, for example, proposed by E. N. Maslov [5], present the grinding zone as a wheel "contact spot" with workpiece within which all grains are uniformly loaded and work under the same conditions. In real a grinding process is subject of the more complex patterns and can not be fully described by averaged parameters such as the average thickness of the cutoff and the like due to the curvilinearity of a wheel contact with workpiece, different in height arrangement of grains on the working surface and their probabilistic participation in cutting. Important theoretical results obtained by different researchers of the grinding process with usage of the probability-theoretic approach show this [6, 7]. It has been established by calculations with use the estimated scheme (Fig. 1) that the position of the boundaries of the complete material dispersion by cutting grains in cutting zone along the arc of wheel contact with workpiece is defined by a ratio of two parameters – maximum (given probabilistic) thickness Hmax of a cut and grinding depth t . In a case t < Hmax (multipass grinding) the boundary accepts approximately a symmetric form of rather axial plane of grinding, in a t > Hmax (deep grinding) – an asymmetric form. 295 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X By calculations it is established that the percent of working grains for a case t > Hmax ; makes about 50%, and for a case t < Hmax – 5 … 10%, i.e. grains pass almost "a trace in a trace" that is an important reserve of increase in productivity of processing as it will be shown. In a case t > Hmax analytical dependence for definition of provision of border assumes a simple air t H H 6 T , (1) max t where tT – the coordinate of the current elementary cylindrical cover by which the removed allowance is conditionally presented in the settlement scheme, m. Respectively, parameters of boundary Hmax and Rmax (parameter of a roughness of processing, m) are described by analytical dependences 0,33 630 X 3 V t0,5 0,5 det Hmax ; (2) m Vc 0,4 X 3 V 0,5 det Rmax 10 , (3) m Vc where X - granularity of a wheel, m; m - volume concentration of grains in a wheel (dimensionless size); V , V - according to the speed of a wheel and a workpiece, m/s; с det 1 1 ; Rc , Rdet - respectively radiuses of a wheel and a workpiece, m. Rdet Rc Values of thickness of the cut received on settlement dependences of a number of authors (Table 1 [4]) show on a big divergence of settlement and experimental data. For example, this divergence exceeds 1000 times for the settlement dependence offered by E. N. Maslov. The most correct result is received with use of dependence (2). The divergence of calculated and experimental H values available here to 40% is max connected with disregarding a wear of cutting grains of a wheel in kinematic model of grinding process. -3 -3 Table 1: Calculated values of thickness of a cut Hmax (basic data: Rpr =8010 m; Rc =15010 m; -6 -3 X =0,22510 m; m =100; Vc =30 m/s; Vpr =1 m/min; t =0,110 m) E. N. Maslov G. B. Lurye A. N. Reznikov F. V. Novikov Experiment Authors [5] [8] [9] [10] data H , max 0,007 0,12 1,1 14,7 10,5 мкм 296 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X The obtained results are clarified in the development of the physical model of the grinding. According to this model the relationship between input and output (technological) parameters is achieved by units of the kinematics and physical parameters as well as the value of linear wear of grain x . It is possible to change the kinematic, physical and, consequently, output (technological) or, on the contrary, the input parameters in a wide ranges with a view to achieving the required output parameters by value changing and taking into account the feedback. New calculated dependencies are established on this basis. They contain a dimensionless coefficient x / H that defines the degree of linear wear of grains within 0…1. For the "sharp" cutting topography of the wheel 0 and conversely, i. e. 1 for the blunted wheel. In the interpretation [4] these dependences have the following forms: 0,33 3 0,5 0,5 2 630 X Vdet t 1 Hmax ; (4) m Vc 1 0,4 2 3 0,5 1 X Vdet Rmax 10 . (5) 1 m Vc It follows from (4) and (5) that the values of the H and R parameters max max decrease with wear of the cutting grains and, correspondingly, a decrease in the dimensionless coefficient ( >0). Therefore divergence between calculated and experimental values Hmax (Table 1) decreases and even it is eliminated. Comparison of experimental values of the maximum thickness of chip with the corresponding calculated values of parameter Hmax showed their approximate coincidence at =0,2 [4]. It follows from this that the accounting of size x of linear wear of grain by means of parameter in settlement dependences allows to bring the theory and practice of grinding into accord. The change of a value of the dimensionless coefficient has greatest influence on values of Hmax and Rmax from all parameters into dependences (4) and (5). It indicates a prevailing role of the wear state of the grains in formation of the key physical and technological parameters of grinding and confirms the hypothesis of effective management of grinding process on the basis of size regulation . In the executed analysis the experimental data of the current level of development of the diamond grinding techniques and technologies from laboratory and production experience were taken into account. This experience is presented by the authors in monographs [6, 11, 12] and is widely based on the successes of the Kharkov Scientific School of Physics of the Cutting and cooperation of universities in the development and applications of stable processes of high-performance diamond grinding, in particular with electrophysical stimulation of processing [13] and on the basis of improvement and use of machine tools [14], tool maintenance [15] and kinematics-parametric organization of advanced technologies [4]. It is ascertained that surface roughness parameter Ra 0,2 Rmax in external cylindrical diamond grinding has been described by the analytical dependence [10]: 297 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 0,4 2 3 0,5 1 X Vdet Ra 2 . (6) 1 m Vc When the flat grinding ( Rdet ) the maximum height of the machined surface voids Rmax and, consequently, surface roughness parameter Ra 0,2 Rmax has been defined by the dependencies: H 14 105 2 X 6 V 2 5 max 5 det Rmax Hmax 2 2 2 2 ; (7) 4t 1 tg m Vc Rc 14 2 X 6 V 2 14 5 det 5 Ra 2 2 2 2 2 Ra0 2 , (8) 1 tg m Vc Rc 1 2 X 6 V 2 5 det where Ra0 2 2 2 2 . tg m Vc Rc It follows from (8) that and X have the greatest influence on parameter of surface roughness Ra . So, the greater the ratio (i. e. the cutting relief of diamond wheel is more smoothed), the smaller Ra . takes the maximum value for a wheel with sharp grains before they wear, when condition =0 is met. The usual calculation practice is based precisely on this condition and does not take into account the wear of grains. The granularity X of the diamond powder in wheel provides significant impact on option Ra that indicates the effectiveness of the solution to the problem of quality of treatment through the application of abrasive wheels with optimal grain size. A grinding depth is not included in the dependence (8). This confirms the effectiveness of the application deep grinding, because an increase in performance occurs without compromising the quality of machined surfaces. It is known that the speed of a workpiece in the practice of deep grinding is 10 ... 100 times less than in multi-pass machining. The roughness of the surface with respect to the parameter can be reduced in 3 … 10 times under such decrease in the speed of the workpiece in conditions of deep grinding as this follows from (8). Thus, theoretically it is shown that the use of deep grinding to reduce the surface roughness at the same time increasing processing performance. This confirms the possibility of single-pass deep grinding not only as a preliminary, but also as a final grinding process which reduces the surface roughness in 3 ... 10 times compared to multi-pass grinding by the abrasive wheel with the same characteristic. Consequently, the use of deep-seated flat grinding allows to combine the operations of preliminary and final grinding in one operation, while ensuring a 10-100-fold increase in the processing capacity and the fulfillment of technological requirements for processing quality. 298 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Presented analysis is valid for an ideal wheel when the parameter (ratio x / H ) is 0. In real conditions of grinding changes within 0 ... 1. This leads to a decrease of the surface roughness calculated on the basis of the dependence (8), Fig. 2. Ra mkm 4 0,75 0,50 3 0,25 2 1 0 0,2 0,4 0,6 0,8 Fig. 2. Dependence of surface roughness Ra on the ratio for different values of Ra0 : 1 – Ra0 = 0,05 μm; 2 – Ra0 = 0,2 μm; 3 – Ra0 = 0,5 μm; 4 – Ra0 = 1 μm. 3. CONCLUSION Thus, the article contains analytical dependences for determination of parameters of surface roughness in diamond grinding. It is shown that the accounting of values of linear wear of grains harmonizes the theory and practice of grinding. This indicates the effectiveness of reducing surface roughness by adjusting the values of linear wear of grains range. Indifference of the adequate calculated procedure to the depth of grinding attests to the effectiveness of deep grinding which allows to combine the prior and final machining operations in one with providing as increase the processing performance in 10 ... 100 times and so execution of technological requirements on quality of processing. REFERENCES [1] Bakool, V. N. et al. Synthetic diamonds in engineering. Kiev, Naukova dumka, 1976, 350 p. – In Russian. [2] Synthetic superhard materials. Ed. by N. V. Novikov. In 3 vols. Vol. 3: The use of synthetic superhard materials. Kiev, Naukova dumka, 1986, 280 p. – In Russian. [3] Ryzhov, E.V. Technological methods to improve the durability of machine parts. Kiev, Naukova dumka, 1984, 272 p. – In Russian. [4] Novikov, F. Kinematics of material removal and forming of surface at grinding. Fiability & Durability, 2013, No. 1(Supplement), pp. 16-22. [5] Маslоv, E. N. Theory of material‟s grinding. Moscow, Mashinostroenie, 1974, 320 p. – In Russian. [6] Physico-mathematical theory of the processes of material‘s treatment and engineering technology. Ed. by F. V. Novikov and A. V. Yakimov. In 10 vols. Vol. 6: Quality of treatment of machine parts, Odessa, Odessa Nat. Polytech. Univ., 2003, 716 p. – In Russian. [7] Novoselov, Yu. K. Dynamics of formation of the surfaces in the abrasive processing. Sevastopol, Publishing house of the SevNTU, 2013, 304 p. – In Russian. 299 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X [8] Lurye, G. B. Grinding of metals. Moscow, Mashinostroenie, 1969, 197 p. – In Russian. [9] Abrasive and diamond processing of materials. Ed. by A. N. Reznikov. Moscow, Mashinostroenie, 1977, 390 p. – In Russian. [10] Novikov, F. V. Physical and kinematic bases of high-performance diamond grinding. PhD Thesis of Techn. Sc. Odessa, Odessa Nat. Polytech. Univ., 1995, 36 p. – In Russian. [11] Gutsalenko, Yu. G. Diamond-spark grinding of high functionality materials [Online resource]. Kharkov, Cursor, NPU «KhPІ», 2016, 272 p. [3,75 Мб], access code: http://web.kpi.kharkov.ua/cutting/dsghfm-monograph.pdf. – In Russian. [12] Novikov, F. V., and I. A. Ryabenkov. Finish machining processing details. Kharkov, Simon Kuznets Kharkov Nat. Univ. of Economics, 2016, 270 p. – In Ukrainian. [13] Machine-building faculty. 125 years as part of KhPI. Ed. by A. I. Grabchenko and M. S. Stepanov. Kharkov, Cursor, 2010, 212 p. – In Ukrainian and Russian. [14] Bezzubenko N. K., and Yu. G. Gutsalenko. Intensive grinding and special design machines. Eastern-European Journal of Enterprise Technologies. 2010, No. 5/1(47), pp. 70- 71. – In Russian. [15] Gutsalenko, Yu. G., C. G. Iancu, E. K. Sevidova, and I. I. Stepanova. Local electrical insulation solutions for tools from superhard materials for their enhanced adaptation to diamond-spark grinding. Physical and Computer Technologies. Proceedings of the 22nd International Scientific and Practical Conference, December 7-9, 2016, Kharkov. Dnepropetrovsk, Publishing house ―Lira‖, pp. 56-59. – In Russian. 300 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X A GROUPOID FRAMEWORK FOR STUDY ASYMPTOTIC BEHAVIOR OF A DISCRETE SYSTEM Mădălina Roxana BUNECI, University Constantin Brâncuşi of Târgu-Jiu, ROMÂNIA Abstract. The purpose of this note is to introduce four different groupoids associated to a function f:XNNX, where X is a uniform space. Thesegroupoids allow to study within a unified framework theasymptotic behavior of thediscrete systems of the form xn+1 = f (xn,,xn-1,…, x ) that do not necessarily n,n0 n0 satisfy the semigroup property of a process. For these systems the groupoidsare associated with the functionsf defined by f(x,n,n ) := (x ,x ,…, x ) with x= . 0 n-1, n-2 n0 Keywords:groupoid; equilibrium point; asymptotically stable equilibrium point. . 1. INTRODUCTION In this article we associate several groupoidsto abstract discrete systems that generalize nonautonomousdiscrete-time processes. Let us recall that the mathematical formalization for a nonautonomousdiscrete-time process includesa space X and a sequence (fn)n of maps fn:XX. Then the nonautonomous difference equation xn+1 = fn(xn) generates a discrete-time process which is defined for all x∈X and n, n0∈ with n ≥ n0 by: (n0, n0, x) := x, (n, n0, x) := f f ... f x . n 1 n 2 n0 The function : XX defined above has the following properties: 1.1) (n0, n0, x) = x for all n0∈ and xX. 1.2) (n2, n0, x) = (n2, n1, (n1, n0, x)) for all n0n1n2 and xX Howeverthere are processes (such as fractional order systems [3]) that do not satisfy semigroup condition 1.2.In this article we consider processes that do not necessarily semigroup condition 1.2. More precisely, we take into consideration the processes generated by the difference equations of the form xn+1 = f (xn,,xn-1,…, ), n≥n0. n,n0 We introduce different groupoids associated to an uniform space X and a function f: XX having the meaning that for all (n,n0) such that n≥n0 f(n,n0,x) = fn-1(xn-1,,xn-2,…, ) with xx . n0 The use of an abstract notion of system allows to study within a unified framework diverse processesand provides a unique language for several different areas of applications. 301 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 2. EQUILIBRIUM AND STABILITY Definition 2.1. Letf: XXbe a function. For each xX we write Ne(x)={n0 :f(n,n0,x)=x for all n , n≥n0}. An element xX is said to be an equilibrium point of the system defined by f: XX if Ne(x), i.e. if there is n0 such that f(n,n0,x)=x for all n , n≥n0. Remark 2.2.Letf: XX be a process that satisfies semigroup condition, i.e f(n2, n0, x) = f (n2, n1, f (n1, n0, x)) for all n0n1n2 and xX. If xe be an equilibrium point of f, then there is n0 such that Ne(x)={n : n≥n0}. Indeed, let n0=min Ne(xe) and let m such that m≥n0. Then for all n≥m we have f(n,n0,xe) =f (n, m, f (m, n0, xe)) (semigroup condition). Since n0Ne(xe), it follows thatxe=f (n, m, xe)for all n≥m, or equivalently, mNe(xe). Let us recall thata uniform space is a set X equipped with a nonempty family A of subsets of X × X (called uniform structure on X) satisfying the following conditions: 1. U for all U , where Δ = { (x, x) : x X }. 2. If U and UV X × X, then V . 3. If U and V , then U ∩ V . 4. For each U there exists V such that VVU, where VV={(x,z): there is y such that (x,y)V and (y,z)V} 5. If U , then U-1 = { (y, x) : (x, y) U } . If is a uniform structure on X, then induces a topology on X: A X is openset if and only if for every xA there exists U such that {y: (x,y)U}A. Definition 2.3.Let X be a space endowed with a uniform structure . Let us consider a system defined by a function f: XX and let xe bean equilibrium point of the system. We write Ns(xe)={n0Ne(xe):for every U there is VU with the property that if (xe,x) VU, then (xe, f(n,n0,x)) U for all n , n≥n0} The equilibrium pointxeis said to bestable if Ne(x). Definition 2.4. Let us consider a system defined by a function f: X X and let us assume that X is endowed with a uniform structure . An equilibrium point xe is said to be attractive if there is n0Ne(xe) and there is U such that for all (xe,x) U we have lim f n,n0 ,x = xe. n An equilibrium point xe is asymptotically stable if it is stable and attracting. 302 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 3. GROUPOIDS ASSOCIATED TO A GENERAL DISCRETE SYSTEM In this section we use the same notation concerning groupoids as in [1] and [2]. Proposition 3.1. Let A be a uniform structure on a set X and let f: XX be a function. If G1 X,A ,f = {(x,n1 k, y, n2) X X : for all U there is nU such that for all n≥nU we have n≥n2, n+k≥n1and (f(n+k,n1,x),f(n,n2,y))U}, Then 1. G1 X,A ,f is a subgroupoid of X X seen as a groupoid under the operations (x,n1 k, y, n2)(y, n2, m, z, n3) = (x, n1,k+m, z, n3) (product) -1 (x, n1, k, y n2) = (y, n2, -k, x, n1) (inversion). 2. If is endowed with the induced topology from X X , then is a topological groupoid. Proof. 1. Let (x, n1, k, y, n2) and let us prove that (y, n2, -k, x, -1 n1) . Let U . Then U , hence there is nU such that for all n≥nUwe have -1 n≥n2, n+k≥n1 and (f(n+k,n1,x),f(n,n2,y))U . Thus for all n ≥ nU+k we have -1 n-k≥n2, n≥n1 and (f(n,n1,x),f(n-k,n2,y))U (or equivalently, (f(n-k,n2,y),f(n,n1,x))U). Consequently, (y,n2, -k, x,n1) . Let (x, n1, k, y,n2), (y,n2, m, z,n3) G X,A ,f and let us prove that (x, n1, k+m, z,n3) . Let U . Then V such that VVU. Since (x, n1, k, y,n2) there is nV such that for all n≥nV, n≥n2, n+k≥n1and (f(n+k,n1,x),f(n,n2,y))V}. Since (y,n2, m, z,n3) , there is n‘V such that for all n≥n‘V, n≥n3, n+m≥n2 and (f(n+m,n2,y),f(n,n3,z))V. Thus for all n≥max{nV-m, n‘V} we have n+m≥n2, n+m+k≥n1 and (f(n+m+k,n1,x),f(n+m,n2,y))V. On the other hand n≥n3, n+m≥n2and (f(n+m,n2,y),f(n,n3,z))V. Therefore (f(n+m+k,n1,x), f(n,n3,z))VVU for all n≥max{nV-m, n‘V}. Hence(x, n1, k+m, z, n3) . 2. Since X X is a topological groupoid, and a subgroupoid, it follows that is a topological groupoid, 303 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Proposition 3.2. Let A be a uniform structure on a set X and let f: XX be a function. If G2 X,A ,f = {(x, k, y, n0) X X : for all U there is nU such that for all n≥nU we have n≥n0, n+k≥n0and (f(n+k,n0,x),f(n,n0,y))U}, Then 1. G2 X,A ,f is a subgroupoid of X X seen as a groupoid under the operations (x, k, y, n0)(y, m, z, n0) = (x, k+m, z, n0) (product) -1 (x, k, y n0) = (y, -k, x, n0) (inversion). 2. If G2 X,A ,f is endowed with the induced topology from X X , then G2 X,A ,f is a topological groupoid. Proof.The proof is similar to that of Proposition 3.1. Remark 3.3. The groupoid introduced in Proposition 3.2 is a disjoint union of groupoids defined in[2 ,Proposition 2.1]. Also can be seen as a subgroupoid G1 X,A ,f introduced in Proposition 3.1 by the identification (x,k, y, n0) (x,n0, k, y, n0). Proposition 3.4. Let be a uniform structure on a set X and let f: XX be a function. If G3 X,A ,f = {(x,n1 k, y, n2) X X : for all U there is nU such that for all n≥nU we have n≥n2, n+k≥n1and (f(n+k,m1,x),f(n,m2,y))U for all m1, m2 such that n+k≥m1≥n1 and n≥ m2≥n2} Then G3 X,A ,f is a subgroupoid of G1 X,A ,f introduced in Proposition 3.1. Proof.The proof is similar to that of Proposition 3.1. Proposition 3.5. Let be a uniform structure on a set X and let f: XX be a function. If G4 X,A ,f = {(x, k, y) X X : there is n0 such that for all U there is nU such that for all n≥nU we have n≥n0, n+k≥n0and (f(n+k,m1,x),f(n,m2,y))U for all m1, m2 such that n+k ≥m1 ≥ n0 and n ≥ m2 ≥ n0} Then 1. G4 X,A ,f is a subgroupoid of X X seen as a groupoid under the operations (x, k, y)(y, m, z) = (x, k+m, z) (product) (x, k, y)-1 = (y, -k, x) (inversion). 304 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 2. If G4 X,A ,f is endowed with the induced topology from X X, then G4 X,A ,f is a topological groupoid. Proof.1. Let (x, k, y) G4 X,A ,f and let us show that (y,-k, x) G4 X,A ,f . Let -1 U A . Since U , it follows that there are n0,nU such that for all n≥nUwe haven≥n0, n+k≥n0and -1 (f(n+k,m1,x),f(n,m2,y))U for all m1, m2 such that n+k≥m1≥n0 and n≥ m2≥n0. -1 Thus for all n ≥ nU+k we haven-k≥n0, n≥n0 and (f(n,m1,x),f(n-k,m2,y))U (or equivalently, (f(n-k,m2,y),f(n,m1,x))U) for all m1, m2 such that n+k≥m1≥n0 and n≥ m2≥n0. Consequently, (y,-k, x) G4 X,A ,f . Let (x, k, y), (y,m, z) G4 X,A ,f and let us prove that (x, n1, k+m, z,n3)G4 X,A ,f . Let U . Then V such that VVU. Since (x, k, y) G4 X,A ,f there are n0,nV such that for all n≥nV we haven≥n0, n+k≥n0 and (f(n+k,m1,x),f(n,m2,y))V for all m1, m2 such that n+k≥m1≥n0 and n≥ m2≥n0. Since (y, m, z) G4 X,A ,f , there aren1,n‘V such that for all n≥n‘V we haven≥n1, n+m≥n1 and (f(n+m,m3,y),f(n,m4,z))V for all m3, m4 such that n+m≥m3≥n1 and n≥ m4≥n1. Thus for all n≥max{nV-m, n‘V} we have n+m≥n0, n+m+k≥n0 and (f(n+m+k,m1,x),f(n+m,m2,y))V for all m1, m2 such that n+m+k≥m1≥n0 and n+m≥ m2≥n0.On the other hand n≥n1, n+m≥n1 and (f(n+m,m3,y),f(n,m4,z))V for all m3, m4 such that n+m≥m3≥n1 and n≥ m4≥n1. Therefore (f(n+m+k,m1,x), f(n,m4,z))VVU for all n≥max{nV-m, n‘V} and all m1, m4 such that n+m+k≥m1≥ max{n0, n1} and n≥ m4≥ max{n0, n1}. Consequently,(x,k+m, z) G4 X,A ,f . 2 . Since G X,A ,f issubgroupoid of the topological groupoidX X is,it follows that G4 X,A ,f is a topological groupoid, Remark 3.6. Let x be an equilibrium point of the system defined by f: XX. x,n0 1. If G is the groupoid G X,A ,f or G X,A ,f , then G ={(x,n0)} 1 2 x,n0 {(x,n0)} for all n0Ne(x). 2. If G is the groupoid G3 X,A ,f and f has semigroup property, then ={(x,n0)} {(x,n0)} for all n0Ne(x). x 3. If G is the groupoid G4 X,A ,f and f has semigroup property, then G x ={x} {x} . Lemma 3.7. Let be a uniform structure on X, let f: XX be a function and let xe be an equilibrium point of the system associated with f and let n0Ne(xe). 305 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 1. If G is the groupoid G1 X,A ,f or G2 X,A ,f , then (x, n1) and (xe, n0) are equivalent units of Gif and only if lim f n,n1 ,x = xe. n 2. If (x, n1) and (xe, n0) are equivalent units of G3 X,A ,f , then = xe. Proof. 1. Let G= .Then (x, n1) and (xe, n0) are equivalent units of G if and only if there is k such that (xe, n0, k,x,n1) G if and only if for every U A there is nU such that for all n≥nU, we have n≥n1, n+k≥n0 and (f(n+k,n0,xe),f(n,n1,x))U. Since xe is an equilibrium point, f(n+k, n0, xe)=xe for all n and k such that n+k ≥ n0. It follows that (x, n1) and (xe, n0) are equivalent units of G if and only if(xe,f(n,n1,x))U for all n≥nU or equivalently, lim f n,n1 ,x = xe. Similarly, we can prove that if G = , then (x, n1) n and (xe, n0) are equivalent units of G if and only if = xe. 2. (x, n1) and (xe, n0)are two equivalent units of G3 X,A ,f if and only if there is k such that (xe, n0, k,x,n1) if and only if for every U there is nU such that for all n≥nU we have n≥n1, n+k≥n0and (f(n+k,m1,xe),f(n,m2,x))U for all m1, m2 such that n+k≥m1≥n0 and n≥ m2≥n1. Since xe is an equilibrium point, f(n+k, n0, xe)=xe for all n and k such that n+k ≥ n0. It follows that if (x, n1) and (xe, n0) are two equivalent units of , then (xe,f(n,n1,x))U for all n≥nU or equivalently, = xe. Corollary 3.8.Let be a uniform structure on X such that U = { (x, x) : x X }. UA andf: XX be a function. Then each orbit of the groupoids G, where G isthe groupoid , G2 X,A ,f or G3 X,A ,f ,contains at most an element (x,n0) with the property that x an equilibrium point of the system associated with f and n0Ne(x). Proof. Let be (x,n1) and (y,n2) two equivalent units of G. Let us assume that x and y are equilibrium points and that n2Ne(y). Then x= lim f n,n2 ,y = lim y =y (since in this case n n the topology on X induced by the uniform structure is Hausdorff). Proposition 3.9. Let be a uniform structure on X, let f: X X be a function, letxe be an equilibrium point and n0Ne(xe). Then xe is attractive if and only if (xe,n0) is in interior of its orbitwith respect to the structure of the groupoid Gi X,A ,f , i=1,2. Proof. Let us assume that (xe, n0) belongs to the interior of [(xe, n0)]X . Then there is U such that {(x,n0): (xe, x) U}[(xe,n0)]. Let xX such that (xe, x) U. Then (x,n0)[(xe,n0)] and according Lemma 3.7, lim f n,n0 ,x = xe. Thus xe is attractive. n Conversely, assume that xe is attractive. 306 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Then there is U A such that if (xe,x) U, then lim f n,n0 ,x = xe. ApplyingLemma n 3.7, if lim f n,n0 ,x = xe, then (x,n0)[(xe,n0)]. Consequently, n {(x,n0): (xe, x) U}[(xe,n0)]. Therefore (xe, n0) belongs to the interior of [(xe, n0)]X . Corollary 3.10.Let be a uniform structure on a set X, let f: XX be a function, let xe be a stable equilibrium point and n0Ne(xe). Then xe is asymptotically stable if and only if (xe,n0) is in interior of its orbitwith respect to the structure of the groupoidG, where G= G1 X,A ,f or G= G2 X,A ,f . REFERENCES [1] M. Buneci, Morphisms of discrete dynamical systems, Discrete and Continuous Dynamical Systems, 29 (1) (2011), 91-107. [2] M. Buneci, A groupoid associated to discrete-time system that does not satisfies semigroup property, Annals of the ―Constantin Brâncuşi‖ University of Târgu-Jiu. Engineering Series. No. 1(2016), 20-23. [2] W. Mitkowski, Is a Fractional System a Dynamical System?,Automatyka 15 (2011), 67-69. 307 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X CARDINALITY AND ENTROPY FORINTUITIONISTIC FUZZY SETS Iuliana Carmen BĂRBĂCIORU , Lecturer Ph. D. ‖Constantin Brâncuşi‖ University, Tg. Jiu Abstract.In this article, a non-probabilistic-type entropy measure for intuitionistic fuzzy sets is proposed, starting from theratio of distances between them proposed in Szmidt and Kacprzyk [13] and De Luca and Termini - first axiomatized non-probabilistic entropy [7]. Keywords: Intuitionistic fuzzy sets; Distance between intuitionistic fuzzy sets; Cardinality of intuitionistic fuzzy set; Entropy of intuitionistic fuzzy set. 1. INTRODUCTION A measure of fuzziness often used and cited in the literature is an entropy first mentioned in 1965 by Zadeh [15-16]. The name entropy was chosen due to an intrinsic similarity of equations to the ones in the Shannon entropy.De Luca and Termini [7], introduced in 1972 some requirements which capture our intuitive comprehension of the degree of fuzziness. In this paper, we propose a measure of fuzziness for intuitionistic fuzzy sets introduced by Atanassov [1-5]. The measure of entropy is a result of a geometric interpretation of intuitionistic fuzzy sets and basically uses a ratio of distances between them [13]. It is also shown that the proposed measure can be stated as the ratio of intuitionistic fuzzy cardinalities: that of and that of , where is the complement of F. 2.PRELIMINARIES In this section, we will present those aspects of intuitionistic fuzzy sets which will be needed in our next discussion. Basic definitions and properties of these setsare those used in [1-5]. Definition 1.A fuzzy set A in Xx may be given as A x,A x x X (1) where each element had a degree of membership. Definition 2.The intuitionistic fuzzy set on a universe X, is form A x,,AA x x x X (2) 308 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X where besides the degree of membership μA : X [0,1] of each element xX to a set A there was considered a degree of non-membership A : X [0,1] , but such that 01AAxx , xX. (3) Definition 3.We call degrees of indeterminacy of x to A, for each A in X the numbers []: AAAx 1 x x, (4) It is a hesitancy degree of x to A [1-5]. It is obvious that 01 A x , . For each fuzzy set AX , evidently, we have: AAAx 11 x x , (5) A geometric interpretation of intuitionistic fuzzy sets and fuzzy sets is presented in Fig.1 [13]. An intuitionistic fuzzy set X is mapped into the triangle ABD [13] in that each element of X corresponds to an element of ABD - in Fig. 1, [13], as an example, a point x ABC corresponding to xX is marked (the values of AAAx,, x x fulfill Eq. (4)). When A x 0, then 1AAxx . In Fig. 1, this condition is fulfilled only on the segment AB. Segment AB may be therefore viewed to represent a fuzzy set. Fig. 1 [13] A geometrical interpretation of an intuitionistic fuzzy set. 309 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X The orthogonal projection of the triangle ABD gives the representation of an intuitionistic fuzzy set on theplane. (The orthogonal projection transfers x' ABDinto x'' ABC .) The interior of the triangle ABC =ABD‟is the area where π>0. Segment AB represents a fuzzy set described by two parameters: µ and ν.The orthogonal projection of the segment AB on the axis µ (the segment [0; 1] is only considered) gives thefuzzy set represented by one parameter µ only. As it was shown in [13], distances between intuitionistic fuzzy sets should be calculated taking into accountthree parameters describing an intuitionistic fuzzy set.The most popular distances between intuitionistic fuzzy sets A, B in X x1, , xn are [13]: - The Euclidian distance between Aand B is defined as follows: n 2 2 2 e(,)()()() A B A x i B x i A x i B xii A xi B x (6) i1 -The Hamming distance: n h(A , B ) AAAAAA x x x x x x (7) i1 Definition 4.[13]Let Abe an intuitionistic fuzzy set in X. First, we define the following two cardinalities of an intuitionistic fuzzy set: - the least (―sure‖) cardinality of A is equal to the so-called sigma-count (cf. [23,24]), and is called here the min Count (min-sigma-count): n minCount ( A ) Ai x (8) i1 - the biggest cardinality of A, which is possible due to , is called the max Count (max-sigma-count),and is equal to n maxCount ( A ) A x i A x i (9) i1 For we have: n C minCount ( A ) Ai x (10) i1 n C maxCount ( A ) A x i A x i (11) i1 The cardinality of an intuitionistic fuzzy set is defined as the interval card A min Count ( A ),max Count ( A ) (12) 310 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 3.ENTROPY De Luca and Termini [7] first axiomatized non-probabilistic entropy, axioms formulated for intuitionistic fuzzy sets are intuitive and have been widely employed in the fuzzy literature. E is an entropy measure if it satisfies axioms[7]: 1. E(A)=0iff A2x (A non-fuzzy); 2. E(A)=1iff Aix 0.5for all i; 3. EAEB()() ifA is less fuzzy than B,i.e., if Aixxi B when B xi 0.5and Aixxi B when B xi 0.5 ; 4. EAE( ) (AC ) . Considertriangle ABD ( Fig. 2. [13] ). Fig.2 A non-fuzzy set (a crisp set) corresponds to the point A (the element fully belongs to it as (AAAx,, x x = (1; 0; 0)) and at point B (the element fully does not belong to it as =(0; 1; 0)). Points A and Brepresenting a crisp set have the degree of fuzziness equal to 0.As shown in [13] : ―An intuitionistic fuzzy set is represented by the triangle ABD and its interior. All points which are above the segment AB have a hesitancy margin greater than 0. The most undefined is point D. As the hesitancy margin for D is equal to 1, we cannot tell if this point belongs or does not belong to the set. The distance from D to A (full belonging) is equal to the distance to B (full non-belonging). So, the degree of fuzziness for D is equal to 100%. But the same situation occurs for all points xi on the segment DG. For DG we have DGxxii DG , DG xi 0 (equality only for point G), and certainly DGxi DG x i DG x i 1. Forevery xi DG we have: distance (A; xi)=distance (B; xi). This geometric representation of an intuitionistic fuzzy set motivates a ratio-based measure of fuzziness (a similar approach was proposed in [13] to calculate the entropy of fuzzy sets): 311 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X a E(F) (13) b where a is a distance (F; Fnear) from F to the nearer point Fnearamong A and B, and b is the distance (F; Ffar)from F to the farther point Ffar among A and B. The geometric interpretation confirms that Eq. (34) satisfies axioms (1)-(4).‖ For n points belonging to an intuitionistic fuzzy set we have 1 n EEF(F) (i ) (14) n i1 Szmidt andKacprzyk [13] remark the factwhile applying the Hamming distances in Eq. (13), the entropy of intuitionistic fuzzy sets is the ratio of the biggest cardinalities ( max Count ) involving only F and Fc. Their result from [13] generalized form of the entropy measure for fuzzy sets presented in [14]. I have noticed that can also be appliedtheEuclidian distancesin Eq. (13),as long as 2 2 2 F xi F xi F xi 1(15) Theorem 1.A generalized entropy measure of an intuitionstic fuzzy set F of n elements is: 1 n 1 minCount (FF C ) ii (16) E(F) C ni1 1 min Count() Fii F where[1-5] C FFminx, CC x ,max x , x i i Fii FF F ii C FFmaxx, CC x ,min x , x . i i Fii FF F ii c Proof. Let F a point having coordinates FFF,, , F a point having coordinates ,,,, , F the nearest non-fuzzy neighbor of F (i.e. point A FFFCCC FFF for Fig. 3a, or point Bfor Fig. 3b), F the farthest non-fuzzy neighbor of F (i.e. point B for a dIFS F, F Fig. 3a, or point A for Fig. 3b).Due to Eq. (34), we have E(F) and for the b dIFS F, F 312 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X situation in Fig. 3a we have [using the Euclidiandistance (6)] Fig. 3 [13] (1 )2 (0 )22 (0 ) 1 2 2 22 2 2 1 E(F) FFF FFFFFF 22 2 1 2 2 2 2 2 21 (0FFF ) (1 ) (0) FFFFFF 1 minCount (F ) = . (17) 1 minCount (F C ) For multiple elements Fi (i=1…n) whose point A is their nearest fuzzy neighbor, Eq. (39) becomes owing to Eqs. (8), (10) and (14) 1 n 1 minCount (F ) E()F (18) C n i1 1 minCotun ()F For the situation in Fig. 3a we have minCount (F FFCC ) min Countmin, ,max ,m in Count (18) FFFFCC minCount (F FFC ) min Countmax , ,min , min Count (19) FFFFCC and a similar consideration for the situation in Fig. 3b. Formulas (19), (20) lead to formulas (18) as formula (16). Example 1.Let us calculate the entropy for an element F1 with the coordinates 1 1 1 1 1 F1 3+ , 3, . 3 3 3 3 3 313 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 1 1 22 1 1 1 2 d( A , F1 ) (1 3+ ) (0 3 ) (0 ) = 0.42265 3 3 3 3 3 1 1 22 1 1 1 2 dF(B,1 ) (0 3+ ) (1 3 ) (0 ) = 1. 5774 3 3 3 3 3 dF(A, ) E(F) 1 = 0.2679. dF(B,1 ) We can obtain the same result using formula (16): C 1 1 1 1 1 CC1 1 1 1 1 F1 3, 3+ , , FFF1 1 3, 3+ , 1 , 3 3 3 3 3 3 3 3 3 3 C 1 1 1 1 1 FFF1 1 3+ , 3, 1 3 3 3 3 3 11 1-( 3+ ) E(F ) 33 =0.2679i.e. the same value. 1 11 1-( - 3) 33 5. CONCLUSIONS Starting from [13] I tried to introduced a measure of entropy for an intuitionistic fuzzy set. This measure is consistent with similar considerations for ordinary fuzzy sets. REFERENCES [1] K. Atanassov, Intuitionistic fuzzy sets, Fuzzy Sets and Systems 20 (1) (1986) 87-96. [2] K. Atanassov, More on intuitionistic fuzzy sets, Fuzzy Sets and Systems 33 (1) (1989) 37- 46. [3] K. Atanassov, New operations de_ned over the intuitionistic fuzzy sets, Fuzzy Sets and Systems 61 (2) (1994) 137-142. [4] K. Atanassov, Operators over interval valued intuitionistic fuzzy sets, Fuzzy Sets and Systems 64 (1994) 159-174. [5] K. Atanassov, Intuitionistic Fuzzy Sets. Theory and Applications, Physica-Verlag, Heidelberg=New York, 1999. [6] P. Burillo, H. Bustince, Entropy on intuitionistic fuzzy sets and on interval-valued fuzzy sets, Fuzzy Sets and Systems 78 (1996) 305-316. 314 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X [7] A. De Luca, S. Termini, A dentition of a non-probabilistic entropy in the setting of fuzzy sets theory, Inform. and Control 20(1972) 301-312. [8] E. Szmidt, J. Kacprzyk, Intuitionistic fuzzy sets in group decision making, Notes IFS 2 (1) (1996) 15-32. [9] E. Szmidt, J. Kacprzyk, Group decision making via intuitionistic fuzzy sets, FUBEST'96, 9-11 October, So_a, Bulgaria, 1996, pp. 107-112. [10] E. Szmidt, J. Kacprzyk, Remarks on some applications of intuitionistic fuzzy sets in decision making, Notes on IFS 2 (3) (1996) 22-31. [11] E. Szmidt, J. Kacprzyk, Intuitionistic fuzzy sets for more realistic group decision making, Proc. of TRANSITION'97, 18-21 June, Warsaw, Poland, 1997, pp. 430-433. [12] E. Szmidt, J. Kacprzyk, On distances between intuitionistic fuzzy sets, Fuzzy Sets and Systems 114 (2000) 505-518. [13] E. Szmidt, J. Kacprzyk, Entropy for intuitionistic fuzzy sets, Fuzzy Sets and Systems 118 (2001) 467-477. [14] B. Kosko, Fuzzy Engineering, Prentice-Hall, Englewood Cli_s, NJ, 1997. [15] L.A. Zadeh, Fuzzy sets, Inform. and Control 8 (1965) 338-353. [16] L.A. Zadeh, The role of fuzzy logic in the management of uncertainty in expert systems, Fuzzy Sets and Systems 11 (1983),199 - 227. 315 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X DETAILS OF OPERATIONS PERFORMED BY THE REMOTE CONTROL ROBOT (CONCEPT) TO THE HORIZONTAL FUEL CHANNEL DURING DECOMMISSIONING PHASE OF NUCLEAR REACTOR CALANDRIA STRUCTURE. PART I: OUTSIDE OPERATIONS Ing. Drd. Constantin POPESCU, Polytechnic University of Bucharest, email: [email protected] Dr. fiz. Gabi ROȘCA-FÂRTAT, Polytechnic University of Bucharest, email: [email protected] Ing. Principal Nicolae PANĂ, Polytechnic University of Bucharest, email: [email protected] Abstract: The authors contribution to this paper is to present a concept solution of a remote control robot (RCR) used for the horizontal fuel channels pressure tube decommissioning in the CANDU nuclear reactor. The authors highlight in this paper, few details of geometry, operations, constraints by kinematics and dynamics of the robot movement outside of the reactor fuel channel. Outside operations performed has as the main steps of dismantling process the followings: positioning front of Calandria structure at the fuel channel to be decommissioned, coupling and locking to the End Fitting (EF), sorting and storage extracted items in the safe container. All steps are performed in automatic mode. The remote control robot (RCR) represents a safety system controlled by sensors and has the capability to analyze any error registered and decide next activities or abort the outside decommissioning procedure in case of any risk rise in order to ensure the environmental and workers protection. Keywords: Decommissioning, CANDU reactor, fuel channel, radiation protection 1. INTRODUCTION Decommissioning the nuclear facility is a complex operation from point of view of process management. Considered the most important step in dismantling the nuclear reactor structure itself the decommissioning of fuel channels is performed as one of the last operations in this process. Because represents such a complex process the decommissioning of the fuel channels requires the maximum radiation protection degree and should be used special tools in remote control mode to perform it. 2. SHORT PRESENTATION OF THE DEVICE CONCEPT The proposed concept solution of the Remote Control Robot (RCR), was designed in order to provide a fully protection of environment and personal against the nuclear radiation during the decommissioning process of the horizontal fuel channels in the CANDU 6 nuclear reactor. 316 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 2.1. GENERAL ASPECTS Designed to work on the both sides of reactor (front and back) the Remote Control Robot (RCR) dismantles one by one the reactor fuel channel components. It‘s operated by a complex platform equipped with a command panel, the general power supply, electrical actuators and geared motors. The platform allows the movements on all axis. From point of view of RCR dimensions can be mentioned the followings: - Length = 8.5 m, approx. - Width = 1.3 m approx. - Height = 1.7 m approx. For platform as principal dimensions are: - Length = 16.7 m, approx. - Width = 7.3 m approx. - Height = 11.9 m approx. 2.2. STRUCTURE ASSEMBLY PRESENTATION The platform (P) is fixed from the beginning of the process on the floor of the reactor chamber in front (or back) of the calandria structure. The Remote Control Robot (RCR) also is mounted on the platform (see Figure 1): 1 - Platform 2 - Remote Control Robot 3 - Front side (or back side) of calandria reactor structure 3 2 1 Fig. 1. The Remote Control Robot on platform, in front of calandria structure 317 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 2.2.1. PRESENTATION OF THE PLATFORM Being fixed on the floor in the calandria structure chamber, the platform represents a strong steel structure. Having an acces ramp this base allows the access of the forklifts (see Figure 2) to retrieve the container when the opertaions are finished every fuel channel. The components are: 1 – Access ramp; 2 – Fixed base; 3 – Mobile base; 4- Vertical support structure; 5- Sled for moving horizontaly and verticaly. 1 3 5 4 2 Fig.2. The platform The movements of the structure are presented in Figure 3: Fig. 3. The platform - degrees of freedom Fig. 4. The mobile sled - degrees of freedom The access ramp (1) and fixed base (2) are fixed on floor, mobile base (3) allows one translation along the X axis, the vertical support structure (4) – joined with mobile base and the sled for moving horizontally and vertically (5) allows three degrees of freedom, one on each axis (see Figure 4) 318 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 2.2.2. PRESENTATION OF THE REMOTE CONTROL ROBOT (RCR) The fuel of the CANDU 6 nuclear reactor is composed by fissile isotopes (U235, Pu239) and fertile materials (U238, U232). The nuclear radiation half-life for each isotope are specified hereunder: - U235 has 704 million years - U238 has 4.468 billion years - Pu239 has 24110 years Due to nuclear radiation (which has harmful effects on living organism through their ionizing effect on the molecular level) during handling of these materials is mandatory to consider all possible protection rules. The Remote Control Robot (RCR) in currently proposed design is a compact and flexible structure and can perform all operations of the decommissioning process: extracting the channel closure plugs, cutting the pressure tube (PT) in many parts during extracting phase of it, extract and cut the end fitting (EF) in two parts. The main parts of RCR are presented in Figure 5: 1 – safety bellows; 2 - connecting pipe; 3 – safety valve; 4 – tool chamber; 5 – external cutting device; 6 – rods chamber; 7 – safety container; 8 – motors chamber; 9 – chassis. 8 6 9 7 5 4 3 2 1 Fig.5. The Remote Control Robot (RCR) 2.2.3. MOVEMENT OF THE REMOTE CONTROL ROBOT (RCR) 2.2.3.1. SAFETY BELLOWS Safety bellows (the bellows is joined to the connecting pipe - see Figure 6): - one translation on Z axis - one rotation around the Z axis Fig. 6. The safety bellows - degrees of freedom 319 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 2.2.3.2. CONNECTING PIPE Connecting pipe (connected at the end fitting - see Figure 7): - one rotation around the Z axis Fig. 7. The connecting pipe - degrees of freedom 2.2.3.3. SAFETY VALVE Safety valve (it closes the fuel channel between some operations - see Figure 8): - one rotation around the Y axis Fig. 8. The safety valve - degrees of freedom 2.2.3.4. TOOL CHAMBER Tool chamber (the sliding holder tools are stored inside - see Figure 9): - two translation movements: on x and Y axis Fig. 9. The tool chamber - degrees of freedom 2.2.3.5. EXTERNAL CUTTING DEVICE External cutting device (to cut the extracted tubes - see Figure 10): - one rotation around the Z axis 320 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Fig. 10. The external cutting device - degrees of freedom 2.2.3.6. RODS CHAMBER Rods chamber (inside there is a support of rod tools - see Figure 11): - one translation on Y axis Fig. 11. The rods chamber - degrees of freedom 2.2.3.7. SAFETY CONTAINER Safety container (from the beginning of operations is fixed on the chassis and will be removed from the RCR chassis when operations are finished with all extracted components inside, stored in safety conditions - see Figure 12): Fig.12. The safety container in removed position 2.2.3.8. MOTORS CHAMBER Motors chamber (fixed on the chassis - see Figure 13): Fig. 13. The motors chamber on the chassis 321 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 2.2.3.9. CHASSIS Chassis (fixed on the platform suports by two strong supports - see Figure 14): Fig.14. The chassis on the supports of platform 2.2.4. THE OUTSIDE OPERATIONS IN DECOMMISSIONING PROCESS PERFORMED BY THE REMOTE CONTROL ROBOT (RCR) The Remote Control Robot (RCR) is designed to perform all operations in decommissioning process accordingly with all radiation protection rules . This process are divided into outside and inside fuel channel operations. Could be defined as main outside operations performed the followings: - positioning of the RCR in front of the fuel channel which should be decommissioned; - set the angle position of fitting for End Fitting (EF) tube; - secure the fuel channel by moving the RCR until the safety bellows touch the front side of the calandria structure; - before starting the decommissioning sequences is mandatory to check the good alignment of RCR and perform all the measurements needed (distances, nuclear radiation level, etc.). 3. CONCLUSIONS In respect with AECL (Atomic Energy of Canada Limited) rules and other international standards for ensure the maximum safety against the nuclear radiation during exploitation life, the proposed design of the Remote Control Robot (RCR) should be continuous upgraded. All the components should be very carefully checked accordingly with maintenance check lists rules and for any deviation registered need to be considered corrective actions. 4. REFERENCES [1] Cheadle B.A., Price E.G., “Operating performance of CANDU pressure tubes”, presented at IAEA Techn. Comm. Mtg on the Exchange of Operational Safety Experience of Heavy Water Reactors, Vienna, 1989. [2] Roger G. Steed, “Nuclear Power in Canada and Beyond”, Ontario, Canada, 2003. [3] Venkatapathi S., Mehmi A., Wong H., “Pressure tube to end fitting roll expanded joints in CANDU PHWRS”, presented at Int. Conf. on Expanded and Rolled Joint Technology, Toronto, Canada, 1993. [4] AECB, “Fundamentals of Power Reactors”, Training Center, Canada. [5] AECL, “CANDU Nuclear Generating Station”, Engineering Company, Canada. [6] ANSTO, “SAR CH19 Decommissioning”, RRRP-7225-EBEAN-002-REV0, 2004. 322 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X [7] CANDU, “EC6 Enhanced CANDU 6 - Technical Summary”, 1003/05.2012. [8] CNCAN, “Law no. 111/1996 on the safe deployment, regulation, authorization and control of nuclear activities”, 1996. [9] CNCAN, “Rules for the decommissioning of objectives and nuclear installations”, 2002. [10] IAEA, “Assessment and management of ageing of major nuclear power plant components important to safety: CANDU pressure tube”, IAEA-TEDOC-1037, Vienna 1998. [11] IAEA, “Assessment and management of ageing of major nuclear power plant components important to safety: CANDU reactor assemblies”, IAEA-TEDOC-1197, Vienna 2001. [12] IAEA, “Decommissioning of Nuclear Power Plants and Research Reactors” Safety Standard Series No. WS-G-2.1, Vienna 1999. [13] IAEA, “Nuclear Power Plant Design Characteristics, Structure of Power Plant Design Characteristics in the IAEA Power Reactor Information System (PRIS)”, IAEA- TECDOC-1544, Vienna 2007. [14] IAEA, “Organization and Management for Decommissioning of Nuclear Facilities”, IAEA-TRS-399, Vienna 2000. [15] IAEA, “Selection of Decommissioning Strategy: Issues and Factors”, IAEA-TECDOC- 1478, Vienna 2005. 323 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X DETAILS OF OPERATIONS PERFORMED BY THE REMOTE CONTROL ROBOT (CONCEPT) TO THE HORIZONTAL FUEL CHANNEL DURING DECOMMISSIONING PHASE OF NUCLEAR REACTOR CALANDRIA STRUCTURE. PART II: INSIDE OPERATIONS Ing. Drd. Constantin POPESCU, Polytechnic University of Bucharest, email: [email protected] Dr. fiz. Gabi ROȘCA-FÂRTAT, Polytechnic University of Bucharest, email: [email protected] Ing. Principal Nicolae PANĂ, Polytechnic University of Bucharest, email: [email protected] Abstract: The authors contribution to this paper is to present a concept solution of a remote control robot (RCR) used for decommissioning of the horizontal fuel channels pressure tube in the CANDU nuclear reactor. In this paper the authors highlight few details of geometry, operations, constraints by kinematics and dynamics of the robot movement inside of the reactor fuel channel. Inside operations performed has as the main steps of dismantling process the followings: unblock and extract the channel closure plug (from End Fitting - EF), unblock and extract the channel shield plug (from Lattice Tube - LT), cut the ends of the pressure tube, extract the pressure tube and cut it in small parts, sorting and storage extracted items in the safe robot container. All steps are performed in automatic mode. The remote control robot (RCR) represents a safety system controlled by sensors and has the capability to analyze any error registered and decide next activities or abort the inside decommissioning procedure in case of any risk rise in order to ensure the environmental and workers protection. Keywords: Decommissioning, CANDU reactor, fuel channel, radiation protection 1. INTRODUCTION Decommissioning the nuclear facility is a complex operation from point of view of process management. Considered the most important step in dismantling the nuclear reactor structure itself the decommissioning of fuel channels is performed as one of the last operations in this process. Because represents such a complex process the decommissioning of the fuel channels requires the maximum radiation protection degree and should be used special tools in remote control mode to perform it. 2. SHORT PRESENTATION OF THE DEVICE CONCEPT The proposed concept solution of the Remote Control Robot (RCR), was designed in order to provide a fully protection of environment and personal against the nuclear radiation during the decommissioning process of the horizontal fuel channels in the CANDU 6 nuclear reactor. 324 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 2.1. GENERAL ASPECTS Designed to work on the both sides of reactor (front and back) the Remote Control Robot (RCR) dismantles one by one the reactor fuel channel components. It‘s operated by a complex platform equipped with a command panel, the general power supply, electrical actuators and geared motors. The platform allows the movements on all axis. From point of view of RCR dimensions can be mentioned the followings: - Length = 8.5 m, approx. - Width = 1.3 m approx. - Height = 1.7 m approx. For platform as principal dimensions are: - Length = 16.7 m, approx. - Width = 7.3 m approx. - Height = 11.9 m approx. 2.2. STRUCTURE ASSEMBLY PRESENTATION The platform (P) is fixed from the beginning of the process on the floor of the reactor chamber in front (or back) of the calandria structure. The Remote Control Robot (RCR) also is mounted on the platform. (see Figure 1): 1 - Platform 2 - Remote Control Robot (coupled to the channel in this picture) 3 - Front side (or back side) of calandria reactor structure 3 2 1 Fig. 1. The Remote Control Robot on platform, in front of calandria structure 325 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X The RCR has as the main components the followings (see Figure 2): 1 – safety bellows; 2 - connecting pipe; 3 – safety valve; 4 – tool chamber; 5 – external cutting device; 6 – rods chamber; 7 – safety container; 8 – motors chamber; 9 – chassis. 8 7 9 6 5 4 3 2 1 Fig. 2. The Remote Control Robot (RCR) 2.3. THE REMOTE CONTROL ROBOT (RCR) – INSIDE OPERATIONS IN DECOMMISSIONING PROCESS Decommissioning process it means in fact extracting one by one of the fuel channel components and their storage in maximum safety mode. The operations will start on back side of Calandria structure and the steps are the followings: unblock and extract the channel closure plug (from End Fitting - EF), and the channel shield plug (from Lattice Tube - LT), cut the end of the pressure tube (on the end closer position of RCR at the moment), extract and cut the end fitting (EF) in two parts, close the fuel channel with safety lid. After back side operations are finished entire assembly (the Remote Control Robot (RCR) and its platform (P)) is moved and fixed on the floor in front side of the calandria structure in the reactor chamber as in Figure 1. The decommissioning process will continue on front side of Calandria structure with the following operations: unblock and extract the channel closure plug (from End Fitting - EF), unblock and extract the channel shield plug (from Lattice Tube - LT), cut the end of the pressure tube (now closer to the front side of structure where the RCR is positioned), extract and cut in two parts the end fitting (EF), extract the pressure tube and cut it in four small parts, close the fuel channel with safety lid. The extracted component are stocked in the safe container. 2.3.1. UNBLOCK AND EXTRACT THE FUEL CHANNEL CLOSURE PLUG AND THE FUEL CHANNEL SHIELD PLUG The operations could start after the RCR is in position on back side of Calandria structure. The steps for the channel closure plug removal are (see Figure 3): - command the sliding tool holder in position and choose the tool for this operation (first position on holder); - command the rods assembly and using the piston located in the motors chamber to engage the rods at the tool ; 326 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X - open safety valve, open the access hatch of the safety container; - connect the tool with the plug and push it to withdraw its fixing claws and remove it from the fuel channel; - store the plug into the safety container; Fig.3. Extraction of fuel channel closure plug - close the access hatch of the safety container; - close safety valve. The steps for the fuel channel shield plug removal are (see Figure 4): - command sliding tool holder in position and choose the tool for current operation (second position on holder); - command the rods assembly and engage the rods at the tool; - open safety valve, open the access hatch of the safety container; - connect the tool with the plug and push it to withdraw its fixing claws and remove it from the fuel channel; - store the plug into the safety container; Fig. 4. Extraction of fuel channel shield plug extraction 2.3.2. CUT THE END OF THE PRESSURE TUBE In Figure 5 are shown the steps of cutting the end of the pressure tube: - command sliding tool holder in position and choose the tool for this operation (third position on holder); - command the rods assembly and engage the rods at the tool; - open safety valve, open the access hatch of the safety container; - the tool is positioned at the end of pressure tube (beyond the joint with the end fitting) and fix it by its claws inside the tube; - start cutting the pressure tube (thickness 4 mm approx.) by cutting-rolling process; the tool has three expandable disk knives; - pull the tool into the sliding holder. 327 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Fig. 5. Cutting pressure tube operation 2.3.3. EXTRACT AND CUT THE END FITTING IN TWO PARTS The steps to extract and cut the end fitting in two parts are shown in the Figure 6: - command sliding tool holder in position and choose the tool for this operation (fourth position on holder); - command the rods assembly and engage the rods at the tool; - fix the tool at the end of end fitting and expand its traction claws; - pull the entire assembly of end fitting and on the middle length stop it into the external cutting tool; - start and cut it in two parts; - both parts of the end fitting will be stored into the safety container; - close the access hatch of the safety container and the safety valve. Fig. 6. Extracting and cutting the end fitting in two parts 2.3.4. SECURE THE FUEL CHANNEL WITH THE SAFETY LID The steps to secure the fuel channel with the safety lid are presented in the Figure 7: - command sliding tool holder in position and choose the safety lid (fifth position on holder); - command the rods assembly and engage the rods at the safety lid; - open safety valve ; - position the safety lid on the fuel channel to close it; - pull back the rods; - close safety valve. 328 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Fig/ 7. Securing the fuel channel using the safety lid – back side The steps presented in points 2.3.1. to 2.3.3. are repeated after the RCR and its platform (P) are moved and fixed in front side of the calandria structure. 2.3.5. EXTRACT THE PRESSURE TUBE AND CUT IT IN FOUR SMALL PARTS Extracting the pressure tube and cut it in four small parts are shown in Figure 8: - command sliding tool holder in position and choose the tool for this operation (third position on holder); - command the rods assembly and engage the rods at the; - open safety valve and open the access hatch of the safety container; - position the tool at the end of pressure tube to expand the fixing claws; - pull the entire tube through the external cutting tool and stop it into this one on the quarter length roughly; - start and cut it and repeat last three steps two times more (until we get four parts from the pressure tube); - all the parts will be stored into the safety container; - close the access hatch of the safety container and after close the safety valve. Fig. 8. Extract the pressure tube and cut it in four small parts Repeat the steps from point 2.3.4. for secure the fuel channel on front side of Calandria structure (see Figure 9). Fig 9. securing the fuel channel with the safety lid – front side 329 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 2.3.6. DELIVERY OF SAFETY CONTAINER FOR TRANSPORTATION For one fuel channel decommissioned is needed one safety container on platform to be available. The access hatch of the safety container will be automatically closed and secured by the RCR, before disconnect it from the system. The safety container will contain at the end of process: two channel closure plugs, two channel shield plugs, four parts from two end fittings and four parts from one pressure tube. The access of a forklift is permitted on platform to safely retrieve and carry the container in the designated warehouse (see Figure 10). Fig. 10. Filled and secured safety container available for transportation 3. CONCLUSIONS In respect with AECL (Atomic Energy of Canada Limited) rules and other international standards for ensure the maximum safety against the nuclear radiation during exploitation life, the proposed design of the Remote Control Robot (RCR) should be continuous upgraded. All the components should be very carefully checked accordingly with maintenance check lists rules and for any deviation registered need to be considered corrective actions. 4. REFERENCES [16] Cheadle B.A., Price E.G., “Operating performance of CANDU pressure tubes”, presented at IAEA Techn. Comm. Mtg on the Exchange of Operational Safety Experience of Heavy Water Reactors, Vienna, 1989. [17] Roger G. Steed, “Nuclear Power in Canada and Beyond”, Ontario, Canada, 2003. [18] Venkatapathi S., Mehmi A., Wong H., “Pressure tube to end fitting roll expanded joints in CANDU PHWRS”, presented at Int. Conf. on Expanded and Rolled Joint Technology, Toronto, Canada, 1993. [19] AECB, “Fundamentals of Power Reactors”, Training Center, Canada. [20] AECL, “CANDU Nuclear Generating Station”, Engineering Company, Canada. [21] ANSTO, “SAR CH19 Decommissioning”, RRRP-7225-EBEAN-002-REV0, 2004. [22] CANDU, “EC6 Enhanced CANDU 6 - Technical Summary”, 1003/05.2012. [23] CNCAN, “Law no. 111/1996 on the safe deployment, regulation, authorization and control of nuclear activities”, 1996. [24] CNCAN, “Rules for the decommissioning of objectives and nuclear installations”, 2002. 330 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X [25] IAEA, “Assessment and management of ageing of major nuclear power plant components important to safety: CANDU pressure tube”, IAEA-TEDOC-1037, Vienna 1998. [26] IAEA, “Assessment and management of ageing of major nuclear power plant components important to safety: CANDU reactor assemblies”, IAEA-TEDOC-1197, Vienna 2001. [27] IAEA, “Decommissioning of Nuclear Power Plants and Research Reactors” Safety Standard Series No. WS-G-2.1, Vienna 1999. [28] IAEA, “Nuclear Power Plant Design Characteristics, Structure of Power Plant Design Characteristics in the IAEA Power Reactor Information System (PRIS)”, IAEA- TECDOC-1544, Vienna 2007. [29] IAEA, “Organization and Management for Decommissioning of Nuclear Facilities”, IAEA-TRS-399, Vienna 2000. [30] IAEA, “Selection of Decommissioning Strategy: Issues and Factors”, IAEA-TECDOC- 1478, Vienna 2005. 331 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X CONSIDERATIONS ON CONTACTLESS ELECTROMAGNETIC MEASUREMENT OF HUMIDITY IN PEDOLOGY Drd. Fiz. Tudor BURLAN-ROTAR, Polytechnic University of Bucharest, [email protected], Prof. Univ. Dr. Ing. Gabriel Dumitru, Polytechnic University of Bucharest, [email protected], Inf. Alina Ioana PRELIPCEANU, Polytechnic University of Bucharest, [email protected] Abstract: To put into practice the conventional determination of resistivity by the galvanic method, requires a relatively large amount of labor and is, therefore, expensive. At the basis of any interpretation are the lateral or vertical variations of re sistivity. The high cost of resistivity maps execution generally means that fewer measurements are made than desirable, with the result that, either (i) the explored area is not large enough to establish a reasonable background, against which the anomaly areas are to be delineated, or (ii) the anomaly areas are obscure and lack definition. The application of electromagnetic techniques (EM) for measuring soil resistivity or conductivity has been known for a long time. Conductivity is preferable in inductive techniques, as instrumentation readings are generally directly proportional to conductivity and inversely proportional to resistivity. The operating principle of this method is: a Tx coil transmitter, supplied with alternating current at an audio frequency, is placed on the ground. An Rx coil receiver is located at a short distance, s, away from the Tx coil. The magnetic field varies in time and the Tx coil induces very small currents in the ground. These currents generate a secondary magnetic field, Hs, which is sensed by the Rx receiver coil, together with primary magnetic field Hp. The ratio of the secondary field, Hs, to the primary magnetic field, Hp, (Hs/Hp) is directly proportional to terrain conductivity. Measuring this ratio, it is possible to construct a device which measures the terrain conductivity by contactless, direct-reading electromagnetic technique. (linear meter.) This latest technique for measuring conductivity by electromagnetic induction, using Very Low Frequency (VLF), is a non-invasive, non-destructive sampling method. The measurements can be done quickly and are not expensive. The Electromagnetic induction technology was originally developed for the mining industry, and has been used in mineral, oil, and gas exploration, hydrogeology studies, and archaeology. In these applications, differences in conductivity of subsurface layers of rock or soil may indicate stratified layers or voids that could be of interest. Key-words: electromagnetic, inductive, conductivity, contactles 1. INTRODUCTION. To put into practice the conventional determination of resistivity by the galvanic method, requires a relatively large amount of labor and is, therefore, expensive. At the basis of any interpretation are the lateral or vertical variations of resistivity. The high cost of resistivity maps execution generally means that fewer measurements are made than desirable, with the result that, either (i) the explored area is not large enough to establish a reasonable background, against which the anomaly areas are to be delineated, or (ii) the anomaly areas are obscure and lack definition. 332 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 2. ELECTROMAGNETIC METHOD FOR MEASURING SOIL RESISTIVITY. The application of electromagnetic techniques (EM) for measuring soil resistivity or conductivity is known for a long time. Conductivity is preferable in inductive techniques, as instrumentation readings are generally directly proportional to conductivity and inversely proportional to resistivity. Figure 1 presents the principle of electromagnetic method for measuring soil conductivity. Fig. 1 Principle of electromagnetic soil conductivity measurement The operating principle of this method is: a Tx transmitter coil supplied with alternating current at a frequency audio is placed on the ground. A Rx receiver coil is located at a distance s from Tx coil. The magnetic field varies in time and the Tx coil induces very small currents in the ground. These currents generate a secondary magnetic field, Hs, which is sensed by the Rx receiver coil, together, with primary magnetic field Hp. The current induced in the coil receiver Rx is directly proportional to the conductivity of the soil: H i S 2 s 0 (1) H p 4 where : H s = secondary magnetic field at Rx coil; 0 = permeability of vacuum; H p = primary magnetic field at Rx coil; = soil conductivity; = 2 f (pulsation); S = distance between coils; f = frequency; i = 1 Since the ratio of the secondary magnetic field and the primary magnetic field is directly proportional to the soil conductivity, can write apparent conductivity indicated by the instrument as defined by the equation: 4 H s (2) a 2 0 S H p 333 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X The unit for conductivity is Siemens per meter or, more conveniently, milli Siemens per meter (mS / m). 3. Sounding the layered earth. 3.1 Two layer earth model. In figure 2 is presented the two layer earth model. Fig. 2: two layer earth model The contribution of the upper layer is: a = 1 [1- RV (z)] (3) The contribution of the lower layer is: = 2 RV (z) (4) The instrument reading is the sum of the two quantities: = [1- (z)] + (z) (5) 3.2 Three layer earth model. In the three layer earth model is used the same procedure: = [1-R( z1 )] + [R( ) – R( z 2 )] + 3 R( z 2 ) (6) In figure 3 is presented the three layer earth model. 334 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Fig. 3: three layer earth model 4. Survey techniques and interpretation 4.1 Sounding a two layer earth by varying intercoil spacing. This technique can be used to measure the vertical variation of conductivity and is made by expanding the intercoil distance similar to the conventional resistivity sounding techniques in which is expanded the electrode distance. Tx transmiting coil retains its location. For each measurement, distance S from coil to coil is increased by moving the Rx coil. Thus, the maximum depth sounding d is also increased. In figure 4 is presented the sounding by varying the intercoil distance S. In the illustration is used horizontal dipole. Fig. 4: Sounding by varying the intercoil distance S. 335 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 4.2 Sounding a two layer earth by varying instrument height. The technique presented above cannot be used for stratification analysis when the instrument is made so that the distance between the coils has a fixed value. However, it is possible to measure the vertical variation of conductivity by varying the instrument heights. In figure 5 is presented the sounding by moving the device vertically. In the illustration is used vertical dipole. It can be seen from figure 5b that at the lifting device on the ground, the area of maximum sensitivity is moved to another layer of soil. Fig. 5 : Sounding by moving the device vertically. a) the device is at ground level. b) the device is lifted off the ground. 5. Measurement technique In agriculture, the device is used to measure the salinity and soil moisture. Other agricultural applications currently include mapping, depth estimation topsoil, sand deposition depth after flood damage estimation due to herbicides, etc. For each of the applications mentioned above, a relationship must be established between the value determined by device and soil characteristic of interest. Once the relationship is established, measurements can be made quickly. To establish a relationship between the value determined by using the soil and the characteristic of interest for selected points on the ground, are taken simultaneously: soil samples (using a probe) and the apparent conductivity of the soil (through measurement device EM) . The data from these points is made EM calibration device. Thus, the final map is drawn deep fertile soil. Experimental correlations were found in moderate to good conductivity between the apparent conductivity and the results of the classical method, the soil samples, the most accepted and precise method for determining soil salinity. A mobile data collection unit is mounted on a wooden trailer away from metal objects and away from the vehicle engine interference, which could affect determinations. In figure 6 is presented the humidity device configuration for s = 1m and maximum sounding deep 1,5 m. 336 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Fig. 6: Configuration for s = 1m and maximum sounding deep 1,5 m. In figure 7 is presented the diagram of the magnetic field lines Fig. 7: The diagram of the magnetic field lines The coils are air-cored for bouth: transmitter and receiver. These coils are in fact magnetic antennas. The mobile unit consists of EM device coupled to an analog to digital convertor, a computer and a receiver of differential global positioning system (DGPS). The unit operates as follows: the analog signal coming from EM is converted into a digital signal and recorded by computer. Together with this information the computer also records your location (where the measurement was performed) received from the DGPS receiver. In the figure 8 is presented the blok diagram of the digital system of the pedology mobile unit. 337 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Fig. 8: The blok diagram of the digital system of the pedology mobile unit 1) the EM device; 2) analog to digital convertor; 3) computer laptop; 4) receiver DGPS Using this device, data of entire fields can be collected quickly, and then, with appropriate software, you can make maps of soil conductivity. For 1 hectar field data can be collected about one hour. After drawing the map of the land, for confirmation, it can be compared with aerial photograph (of the same pitch) made in the vegetation season. In the early 1980s, electromagnetic induction method (EM) has been accepted as a useful method for getting maps of soil salinity. The method provides assessment tools to monitor the salinity. Information about the depth of topsoil are a valuable tool in choosing appropriate crop management needs. 6. Experimental Results EM device indicate areas where higher electrical conductivity (soil more fertile) are marked on the map with dark green - green crops. Soil areas with lower conductivity, are marked with color light brown - areas where coverage is less dense crop yellowing occurs due to moisture stress. Using aerial photography to see plant cover is easy to see differences in productivity potential and how well models of potential productivity are correlated with measurements of soil conductivity using EM device. The EM behave linearly proportional to the conductivity of the soil when the distance between the coils is less than the depth of penetration. However, in soils with a higher apparent conductivity of 80 mS / m, EM measurements are not linearly proportional to the conductivity of the soil. 7. Conclusions The device for measuring the conductivity of materials by electromagnetic method (without contact) has a wide range of applications. Its usefulness in areas such as geology (search for metal ores, oil, salt, etc.), archeology, agriculture (for measuring humidity, salinity) was confirmed in time. 8. References [1] Amen, A. E., "Soil Survey of Logan County, Colorado". USDA-Soil Conservation. Service and the Colorado Agricultural Experiment Station. (1977), U. S. Government Printing Office, Washington, D.C. 252 p [2] Brus D.J., Knotters M, van Dooremolen P., van Kernebeek P. & van Seeters R.J.M. „The Use of Electromagnetic Measurements of Apparent Soil Electrical Conductivity to Predict the Boulder Clay Depth”. (1992). Geoderma 55, 79-84. [3] Cannon ME, McKenzie RC & Lachapelle GP. „Soil Salinity Mapping with Electromagnetic Induction and Satellite-Based Navigation Methods”. (1994). Canadian Journal of Soil Science 74, 335-343. 338 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X [4] de Jong, E., A. K. Ballantyne, D. R. Cameron, and D. L. Read. „Measurement of Apparent Electrical Conductivity of Soils by an Electromagnetic Induction Probe to Aid Salinity Surveys” (1979), Soil Sci. Soc. Am. J. 43:810-812. [5] Diaz, L., and J. Herrero. „Salinity Estimates in Irrigated Soils Using Electromagnetic Induction”. (1992). Soil Sci. 154(2): 151-157. [6] Doolitlle JA Sudduth KA Kitchen NR & Indorante SJ. „Estimating Depths to Clay Pans Using Electromagnetic Induction Methods”. (1994). Journal of Soil and Water Conservation 49, 572-575. [7] Jaynes D.B., T.S. Colvin, and J. Ambuel „Yield Mapping by Electromagnetic Induction”. p. 383-394. In P.C. Robert, R.H. Rust, and W.E. Larson (ed.), Proc. 2nd Intl. Conf. on Site-Specific Management for agricultural Systems. (1995). ASA, CSSA, and SSSA, Madison, WI. [8] J.D., N.A. Manteghi, P.J. Shouse and W.J. Alves, “Soil Electrical Conductivity and Soil Salinity” New Formulations and Calibrations, Rhoades, Soil Sci. Soc. Am. J. 53:433-439, 1989. [9] Johnston, M. A., M. J. Savage, J. H. Moolman, and H. M. du Plessis „Evaluation of Calibration Methods for Interpreting Soil Salinity from Electromagnetic Induction Measurements”. (1997), Soil Sci. Soc. Am. J., 61:1627-1633. [10] Kachanoski RG Gregorich EG & Van Wesenbeeck IJ, „Estimating Spatial Variations of Soil Water Content Using Noncontacting Electromagnetic Inductive Methods”. (1998). Canadian Journal of Soil Science 68, 715-722. [11] Lesch, S. M., J. Herrero, and J. D. Rhoades „Monitoring for Temporal Changes in Soil Salinity Using Electromagnetic Induction Techniques”. (1998), Soil Sci. Soc. Am. J. 62:232-242. [12] Rhoades, J.D. and D.L. Corwin. „Determining Soil Electrical Conductivity-Depth Relations Using an Inductive Electromagnetic Soil Conductivity Meter”. (1991)., Soil Sci. Soc. Am. J. 45:255-260. [13] Rhoades, J.D., N.A. Manteghi, P.J. Shouse, and W.J. Alves „Soil Electrical Conductivity and Soil Salinity: New Formulations and Calibrations”. (1989)., Soil Sci. Soc. Am. J. 53:433-439. [14] Rhoades, J. D., P. A. Raats, and R. J. Prather. “Effects of Liquid-Phase Electrical Conductivity, Water Content, and Surface Conductivity on Bulk Soil Electrical Conductivity” (1976), Soil Sci. Soc. Am. J. 40:651-655. [15] Rhoades, J. D., S. M. Lesch, P. J. Shouse, and W. J. Alves „New Calibrations for Determining Soil Electrical Conductivity Depth Relations from Electromagnetic Measurements”. (1989), Soil Sci. Soc. Am. J. 53:74-79. [16] Sheets K.R. and J.M.H. Hendrickx, “Noninvasive Soil Water Content Measurement Using Electromagnetic Induction”, Water Resources Res. 31(10): 2401-2409, 1995. [17] Sudduth KA Kitchen NR Hughes DF & Drummond ST. „Electromagnetic Induction Sensing as an Indicator of Productivity on Claypan Soils”, (1995) Proceedings of the Second International Conference on Site Specific Management for Agricultural Systems. (Eds. Probert, P.G., Rust, R.I.H. & Larson, W.E.). pp 671-681. [18] Wait, J. R., „A Note on the Electromagnetic Response of a Stratified Earth”. Geophysics V.27, 1962. [19] Williams, B.G., Fiddler, F-T. „The Use of Electromagnetic Induction for Locating Subsurface Saline Material. In „Relation of Groundwater Quantity and Quality”, (1983), (Proceedings of the Hamburg Symposium, August 1983). IAHS Publishing No 146 189-196. 339 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X [20] Williams, B. G., and G. C. Baker, „An Electromagnetic Induction Technique for Reconnaissance Surveys of Soil Salinity Hazards”. (1982), Australian Journal of Soil Res. 20: 107-118. [21] Williams B.G. & Hoey D „The Use of Electromagnetic Induction to Detect the Spatial Variability of the Salt and Clay Contents of Soil”. (1987), Australian Journal of Soil Research 25, 21-28. [22] Wollenhaupt, N. C., J. L. Richardson, J. E. Foss, and E. C. Doll. „A Rapid Method for Estimating Weighted Soil Salinity from Apparent Soil Electrical Conductivity Measured with an Aboveground Electromagnetic Induction Meter”, (1986), , Can J. Soil Sci. 66:315- 321. 340 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X CONSIDERATIONS ON CONTACTLESS MEASUREMENTS IN HYDROGEOLOGY USING VERY LOW FREQUENCY ELECTROMAGNETIC TECHNIQUES Drd. Fiz. Tudor BURLAN-ROTAR, Polytechnic University of Bucharest, [email protected], Prof. Univ. Dr. Ing. Gabriel Dumitru, Polytechnic University of Bucharest, [email protected], Inf. Alina Ioana PRELIPCEANU, Polytechnic University of Bucharest, [email protected] Abstract: Studies of groundwater consist in data acquisition, their processing and interpretation. In areas of interest hydrogeological is assumed that there is a network of wells drilled. This network provides a first in the hydrogeological information. Electromagnetic (EM) mapping through the use of such areas, using data obtained from existing network of wells drilled, calibration and confirmation. Measurements using the EM can highlight the existence of several layers with different characteristics: clay, limestone, sand, etc. Studies of groundwater interpretation are used for developing a regional hydrogeologic model. The application of electromagnetic techniques for measuring soil resistivity or conductivity has been known for a long time. Conductivity is preferable in inductive techniques, as instrumentation readings are generally directly proportional to conductivity and inversely proportional to resistivity. The operating principle of this method is: a Tx coil transmitter, supplied with alternating current at an audio frequency, is placed on the ground. An Rx coil receiver is located at a short distance, s, away from the Tx coil. The magnetic field varies in time and the Tx coil induces very small currents in the ground. These currents generate a secondary magnetic field, Hs, which is sensed by the Rx receiver coil, together, with primary magnetic field Hp. The ratio of the secondary field, Hs, to the primary magnetic field, Hp, (Hs/Hp) is directly proportional to terrain conductivity. Measuring this ratio, it is possible to construct a device which measures the terrain conductivity by contactless, direct-reading electromagnetic technique (linear meter). This technique for measuring conductivity by electromagnetic induction, using Very Low Frequency (VLF), is a non-intrusive, non-destructive sampling method. The measurements can be done quickly and are not expensive. The Electromagnetic induction technology was originally developed for the mining industry, and has been used in mineral, oil, and gas exploration, and archaeology. In these applications, differences in conductivity of subsurface layers of rock or soil may indicate stratified layers or voids that could be of interest. Key-words: electromagnetic, inductive, conductivity, contactless. 1. Introduction Studies of groundwater consist in data acquisition, their processing and interpretation. In areas of interest hydrogeological is assumed that there is a network of wells drilled. This network provides a first in the hydrogeological information. Electromagnetic (EM) mapping through the use of such areas, using data obtained from existing network of wells drilled, calibration and confirmation. Measurements using the EM can highlight the existence of several layers with different characteristics: clay, limestone, sand, etc. Studies of groundwater interpretation are used for developing a regional hydrogeologic model. 341 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 2. Electromagnetic method for measuring soil resistivity. The application of electromagnetic techniques (EM) for measuring soil resistivity or conductivity is known for a long time. Conductivity is preferable in inductive techniques, as instrumentation readings are generally directly proportional to conductivity and inversely proportional to resistivity Figure 1 presents the principle of electromagnetic method for measuring soil conductivity. Fig.1 Principle of electromagnetic soil conductivity measurement The operating principle of this method is: a Tx transmitter coil supplied with alternating current at a frequency audio is placed on the ground. A Rx receiver coil is located at a distance s from Tx coil. The magnetic field varies in time and the Tx coil induces very small currents in the ground. These currents generate a secondary magnetic field, Hs, which is sensed by the Rx receiver coil, together, with primary magnetic field Hp. The current induced in the coil receiver Rx is directly proportional to the conductivity of the soil: H i S 2 s 0 (1) H p 4 where : H s = secondary magnetic field at Rx coil; 0 = permeability of vacuum; H p = primary magnetic field at Rx coil; = soil conductivity; = 2 f (pulsation); S = distance between coils; f = frequency; i = 1 342 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Since the ratio of the secondary magnetic field and the primary magnetic field is directly proportional to the soil conductivity, can write apparent conductivity indicated by the instrument as defined by the equation: 4 H s (2) a 2 0 S H p The unit for conductivity is Siemens per meter or, more conveniently, milli Siemens per meter (mS / m). 3. Characteristics of the device according to the type of polarization Table 1 presents the penetration depth depending on the type of polarization and the distance between coils. The penetration depth ( meters ) Distance between coils ( meters ) Horizontal dipole Vertical dipole 10 7,5 15 20 15 30 40 30 60 Consider the following initial conditions: For a homogeneous or stratified horizontal ground current flow is entirely horizontal. In addition, the current flow at any point in the ground is independent of current flow at any point and the magnetic coupling between the current loops are negligible. Accordingly the depth of penetration is limited only by the distance between the coils. The response of the device as a function of depth (in a homogeneous halfspace): Whether on a homogeneous halfspace surface which are located the Tx and Rx coils at distance s. Consider a thin layer dz at a depth z. The thin layer dz at a depth z is presented in fig. 2. Fig. 2 The thin layer dz at the depth z 343 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X The depth plotted as fractions of s - distance between coils, is represented on Ox : depth z (3) s It can be built, so for the vertical polarization, the function V (z) , which describes the relative contribution of the secondary magnetic field due to a thin layer at a depth z. In figure 3 is presented the function for the vertical polarization. It is observed that the layer located at a depth of about 0.4s gives maximum contribution of secondary magnetic field, but that layer to a depth of 1.5s, yet contribute significantly. Fig. 3 Operation of the device in vertical polarization mode (VD) It is interesting to note that in the neighborhood of the surface layer has a very small s contribution to the secondary magnetic field and, therefore, this configuration is insensitive to changes in conductivity near the surface. In figure 4 is presented the function H (z) for the case when the transmitter and receiver operate in the operating mode to horizontal coplanar dipoles. 344 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Fig. 4 Operation of the device in horizontal polarization mode (HD) For comparison of the different ways to respond to layers at different depths, now are shown in the same coordinate system, both functions: vertical polarization (VD) and horizontal polarization (HD). In figure 5 are presented both functions: V (z) and H (z) . Fig. 5 Representation of both functions: and (to highlight how different the response of different layers) It is noted that at depths slightly smaller than the distance between the coils, the signal measured by the device is about twice higher for vertical polarization to horizontal polarization case. The horizontal dipole orientation, the instrument is more sensitive to soil layers in the vicinity. The vertical dipole orientation device is more sensitive to the deeper layers. 345 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Thus, by performing measurements in both modes, it is possible to measure the increase or decrease in conductivity with depth. 4. Block diagram of the device based on the method of electromagnetic (EM) Fig. 6 Block diagram of the device and polarization types used: Vertical dipole (VD) and horizontal dipole (HD) The device is composed of two parts. The emission consists of a transmitting coil that receives signal Tx emission module (a square wave generator of fixed frequency of 10-20 kHz). The reception desk is made of Rx coil and receiver (amplifier with one or more floors, followed by a detector). Receiver modulator output is connected to a measuring instrument (mA) through a potentiometric circuit. Level zero is set in the potentiometer. Figure 6 presents a block diagram of the device and the types of polarization used: vertical dipole (VD) and horizontal dipole (HD). The polarization is selected by positioning plan in which there are two coils, Tx coil and Rx coil. It uses horizontal polarization dipole when the coil axis is parallel to the soil surface and vertical dipole when the coil axis is perpendicular to the soil surface. 5. Hydrogeology measurements. The operating principle of this method is: a Tx coil transmitter, supplied with alternating current at an audio frequency, is placed on the ground. An Rx coil receiver is located at a short distance, s, away from the Tx coil. The magnetic field varies in time and the Tx coil induces very small currents in the ground. These currents generate a secondary magnetic field, Hs, which is sensed by the Rx receiver coil, together, with primary magnetic field Hp. The ratio of the secondary field, Hs, to the primary magnetic field, Hp, (Hs/Hp) is directly proportional to terrain conductivity. Measuring this ratio, it is possible to construct a device which measures the terrain conductivity by contactless, direct-reading electromagnetic technique (linear meter). This technique for measuring conductivity by electromagnetic induction, using Very Low Frequency (VLF), is a non-intrusive, non-destructive sampling method. The measurements can be done quickly and are not expensive. 346 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Wells are drilled at a minimum distance of 3 – 5 Km within 15 – 20 Km. The distances of 30 – 40 Km are too high to provide a basic level of primary information. Measurements using the EM can highlight the existence of several layers with different characteristics: clay, limestone, sand, etc. Type of sediment permeability and thus the condition of existing water quantity. It should be taken into acount and the season in which they occur measurements: rainy or dry season. The transmitter( Tx) and receiver(Rx) must be kept dry to function properly. This is accomplished by floating them in plastic storage boxes. The receiver coil must be perched on legs made from four-foot long wooden dowels The transmitter output current of 3A into a 100 m x 100 m loop gives good response and resolution to depths of 150 m. So it is an ideal instrument for resistivity sounding over a large area. When the transmitter output current of 2,5 A to an 8 – turn, 5 m x 5 m moving transmitter loop with base frequency of 75 Hz, the configuration is optimal for horizontal loops (vertical dipole) surveys for mineral exploration to shallow depths, and for groundwater exploration. The transmitter has a 12V battery. The transmitter current is a modified symmetrical square wave. In figure 7 are presented the transmitter current and the signal in the receiver loop. Fig. 7: the transmitter current and the signal in the receiver loop The receiver coil is located at the middle of the transmitter loop. In figure 8 is presented the central loop sounding configuration. Fig. 8 Central loop sounding configuration. red: Tx transmitter and transmitter loop, blue: Rx receiver and receiver loop 347 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Better spatial resolution is obtained with a moving transmitter configuration with a short intercoil spacing, but is limited to ashallower depth of exploration. Greatest depth is obtained with large fixed loop. The loops are air-cored coils for bouth: transmitter and receiver. The system is adequate to be employed for general geological applications, such as mapping groundwater. 6. Conclusions In areas in vicinity of the sea is likely to be revealed some degree of intrusion of saltwater. Areas with saltwater and freshwater identify the difference in resistivity. The interpreted EM measurements show a distinct range of layer resistivities, which correspond to freshwater and saltwater saturated materials. Based on this and the results of geophysical borehole measurements, the EM results can be used to map. The data points which do not fit in smoothly with neighboring points are rejected. . On the map are indicated depths separate. 7. References [1] Diaz, L. and J. Herrero, ―Salinity Estimates in Irrigated Soils Using Electromagnetic Induction”, Soil Sci. 154(2): 151-157, 1992. [2] Kachanoski RG Gregorich EG & Van Wesenbeeck IJ, “Estimating Spatial Variations of Soil Water Content Using Noncontacting Electromagnetic Inductive Methods”, Canadian Journal of Soil Science 68, 715-722, 1988. [3] Rhoades, J. D., P. A. Raats and R. J. Prather, “Effects of Liquid-Phase Electrical Conductivity, Water Content, and Surface Conductivity on Bulk Soil Electrical Conductivity”, Soil Sci. Soc. Am. J. 40:651-655, 1976. [4] Sheets K.R. and J.M.H. Hendrickx, “Noninvasive Soil Water Content Measurement Using Electromagnetic Induction”, Water Resources Res. 31(10): 2401-2409, 1995. [5] Williams, B.G., Fiddler, F-T., “The Use of Electromagnetic Induction for Locating Subsurface Saline Material. In Relation of Groundwater Quantity and Quality”, (Proceedings of the Hamburg Symposium, August 1983), IAHS Publishing No 146 189-196, 1983. [6] Williams BG & Hoey D, “The Use of Electromagnetic Induction to Detect the Spatial Variability of the Salt and Clay Contents of Soil”, Australian Journal of Soil Research 25, 21- 28, 1987. 348 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X A CONTERPORARYAPPROACH FOR OBTAINING REGULARLY SHAPED ROUGHNESS BY BALL-BURNISHING PROCESS CARIED OUT USINGCNC CONTROLEDMILLING MACHINES Associate Professor PhD. STOYAN SLAVOV, [email protected], Department of Technology of Machine Tools and Manufacturing, Technical University of Varna, Bulgaria Abstract:The present work describes the main advantages of the implementation a newapproachfor ball-burnishing process, for precisely formation of regularly shaped roughness on external planar and cylindrical functional surfaces from machine parts. The considered approach includes the capabilities of contemporary CAM software products for automated programing, and 3-axis vertical or 4-axis horizontal machining centrescontrolled by CNC. A mathematical model developed for generating the sinusoidal curves, which represents needed toolpaths and an algorithm for obtaining the NC-code for corresponding machine tools are presented. The principle of the purposed processing schemes for ball burnishingof external planar or cylindrical surfaces is described and conclusions about the advantages of the purposed approach are given. Key words:regularly shaped roughness; ball-burnishing process; CNC controled machine tools; CAD/CAM. 1. INTRODUCTION There are many examples, which confirmed thatthe specific roughness of the contact surfaces (see Figure 1 a ÷ d), obtained after the classical finishing machining processes (likefinish milling, turning, grinding, polishing, etc.), do not always meet the specific operational requirements of the machine parts.It mainly concerns some cases ofheavily loadedsliding friction pairs, surfaces that interact with fluid streams, and those designed to reflect or distract different types of electromagnetic radiation (e.g. light, heat and other types of of radiation) [2,9,10,11]. a) b) c) d) Fig. 1.Motif profiles with typical forms of roughness occurring after implementation of some of the traditional methods for finishing machining [1]: а) after finish turning; b) after finish milling; c) after grinding; d) after polishing. In this regard, there are some finishing processes based on plastic deformation of the surface layer[1,2,3,11],as conventional ball-burnishing process and ball-burnishing process assisted by vibrations, after implementation of which can be obtained specific plastic deformed roughness on the processed surface. Comparing two variations of this method, the vibration assisted ball-burnishing process is characterized with better opportunities for control the parameters of the quality of the obtained regularlyshaped surfaces [1, 11]. This method is 349 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X basedon plastic deformation in cold state of the surface layer of the workpiece by pressing the hard steel ball with certain external pressing (so cold burnishing) force, and also the ball elementtraveling along to complex (sinusoidal) toolpath trajectory, provided by an eccentric mechanism. By using certain combinations of the regime parameters of the process, it is possible to obtain an appropriate combination of traces by plastic deformation and thus obtain patterns with a regularly shaped roughness, of the type shown in Figure 2 (a ÷ f). They are characterized with parameters of the profile of roughness asperities and operational characteristics, which radically differ from those, obtained after conventional finishing methods for machining by cutting, like turning, milling, grinding, etc.[4] (see Figure 1). Type I Type II Type III Type IV Type V a) b) c) d) e) f) Motif profiles Fig. 2. Typical surface patterns with regularly shaped roughness, obtainedafter implementationof the vibration assisted ball-burnishing process [11]: a) a system of not touching each other traces; b) a system of touching each other traces; c) a system of intersecting each other traces; d) regularlyshaped roughness with hexagonal cells; e) regularlyshaped roughness with rectangular cells; f) completely overlapping each other traces. For example, depending on the physical and mechanical characteristics of the processed material and regime parameters of this type of ball-burnishing process (the burnishing force, feed rates, and the diameter of the ball) the following parameters of roughness are usually obtained: • very large radii of curvature of the roughness asperities (usually between 800 and 8000 μm) at maximum height from 30 to 75 μm, • small angles of inclination of the roughness asperities profile from 00 30' to 30, and • large pitch between the adjacent peaks of the roughness (between 500 and 3500 μm). Thus, the conditions for contact interaction between functional surfaces of the machine parts after implementation classical or vibration assisted ball-burnishingprocesses are significantly improved [1,2,9]. Moreover, after implementation of these methods the hardness in the surface layer of the parts increases creating compressive residual stresses, which significantly improves the wear resistance and their fatigue life [11]. Along with operational advantages after implementation of the vibration assisted ball- burnishing process [2,3,8,9, and 12], there are some technological limitations when using manually controlled machine tools forperforming this finishing process. They are as follows: a) The standard construction of the manually controlled machine tools is usually insufficient for obtaining the needed complex trajectory of movement of the ball tool. This requires additional eccentricdevices to be usedto provide the needed oscillating movement of 350 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X the ball tool. This complicates the application of the method as well as introduces forced oscillations into the system: machine – tool– workpiece, which may cause unstable work; b) Feedrates of the manually controlled metal cutting machines can be changed in a limited range, and only with certain values, which is leads to restrictions in the achieved form and dimensions of the cells from the regularly shaped roughness; c) The lack of general kinematic synchronization between spindle and feed movements in manually controlled milling machines,andwith the oscillations of the ball-tool often results in non-uniformityinobtained shape and size of the cells in the same processing area; d) In order to prevent the formation of cells with significantly different shape and size within the processed areait is necessary to interrupt the contact between the ball tool and the burnished surface [8]. This often leads to shock loads of the tool and shortens its service period; e) Relatively low feedrates, which can be achieved by using manually controlled machines, combined with the need to interruptthe contact between the ball element and the processed surface, leads to a significant increase in the processing time and consequently low productivity. Due to these reasons, ball-burnishing processnot yet received wide distribution, and its application is limited tomanufacturing onlyfor specific machine parts in terms of single item /one off/ type of the production. 2. MODELING AND PROCESSING REGULARLY SHAPEDROUGHNESS USING CONTEMPORARY CAM SOFTWARE AND CNC CONTROLED MACHINE TOOLS 2.1. Particularities in modelling of the regularlyshaped roughness Obtaining regularly shaped roughness of the types, shown in Figure 2 (a ÷ f) is possible if appropriate CAM software and CNC machine tool are used, instead of manually controlled machine tools with additional generating oscillations devices. In this case, the described above disadvantages and limitations of the traditional processing approaches for vibration assisted ball-burnishing process can be considerably minimized and some of them can be completely avoided. This is due to high accuracy, stability, speeds, and feedrates of the contemporary CNC machine tools and their ability to provide complex interpolated trajectories for movement of the tools around the machined surface. The ability for simultaneous control of the tool movement in two (or more) axes in modern CNC control systems eliminates the necessity of using additional devices for providing oscillations. Therefore, by using them it is possible to achieveall types of the regular shaped surface roughness patterns, shown in Figure 2 (a ÷ f) with high accuracy and repeatability of the parameters of the shape and size of the cells. 351 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 2.2 Modellingthe toolpaths for planar and cylindrical external surfaces From Figure 2 (a ÷ f) can be seen, that all five types of regularly shaped roughness can be obtained by creating tangent, intersected or overlapped traces by the ball tool. It is enough for the ball tool to perform only a sinusoidal trajectory, but for the different patterns, the corresponding sinusoidshavedifferentcombinations of peak amplitude (2.a) and period (Sy), as well as the individual toolpaths are spaced at different distances (Sx) (or rotated at different angles α) from each other (see Figure 3. a, b). Therefore,it is possible to create mathematical model, based on sinusoidal curves for describing the geometrical parameters of the all five types of patterns with regularly shaped roughness, shown in Figure 3 for external surfaces from machine parts, which have planar (a) or cylindrical (b) shape. Proposed mathematical model is based on a pair of odd periodic functions forming the 2D sinusoidal curves of the type shown in Table 1, whichhave phase shiftbetween 0 and 180 degrees. The mathematical model can be presented with the following pair of equations, used for calculation of the coordinates of the points of each of the sinusoidal curves: L Yi i sy L S (1) Xi a.sin(2 i ) sy where: L, [mm] is length of the sinusoidal curves (which is depend on the length of the ball- burnished area); 2а, [mm] is the amplitude between peaks of the sine wave; Sy, [mm] is the period of the sine wave; L/Sy= k is the number of individual sine waves within the length L of one single curve; i = 0...n is the number of points of the sinusoidal curves; φ= 0...1800is the angle of the phase shift; s (s = 1,3,5…) is exponent parameter, which influences the shape of the curve; Table 1 shows resulting curves,obtained withexample values of the parameters (k = 5,a = 1, i = 300, φ = 1800) in the pair of equations (1) and for three different exponent values s = 1, 3, and 5. As seen from Table 1, the resulting curve has a sinusoidal shape when s = 1, Trajectory of movement of Sy Trajectory of movement of X the tool the tool Z D α Y Y x S a Y’ 2 H Y’’ Sy L X L 352 a) Fiabilitate si Durabilitate b) - Fiability & Durability No 1/ 2017 Fig. 3. Diagrams of the toolpaths ofEditura the ball “Academicatool for obtaining Brâncuşi regularly” , Târgu shaped Jiu, roughness: ISSN 1844 – 640X a) for planar surfaces using 3-axis vertical milling machine, b) for cylindrical surfacesusing 4-axis horizontal milling center. approximately sinusoidal shape when s = 3, and when s = 5 (and greater) the curve become more and more excessive. One of the most important condition aboutregular shaped roughness from IV-th type (see Figure 2 d, e) is to obtain cells with a high repeatability of the shape and dimensions, and therefore the shape of the toolpath curves will have a significant effect on this condition. The areas ΣA and B of curve shapes are calculated (as shown in Table 1), for comparison the degree of inhomogeneity which will be obtained at the three different values of the exponents in pair equations (1). They can be determined by using the following equations: Table 1: Types of curves obtained from pair of equations (1) for three values of the exponent s. Shape of curves and area Percentage difference in areas Values of the exponent dimensions ΣA and B 75.19% s = 1 (B > ΣA) 26.26% s = 3 (ΣA > B) 48.59% s = 5 (ΣA > B) s S B a sin(x) .dx A a a sin(x) .dx (2) 0 0 Changing the values of the s in formulas (2) and integrating them in the range from 0 to π, the following expressions for the areas are obtained: - for s=1: B= 2.a, and ΣA= a. (π - 2); - for s=3: B= (4.a)/3, and ΣA= a. (3.π - 4)/3; - for s=5: B= (16.a)/15, and ΣA= a. (15.π - 16)/15; Setting the parameter a = 1 in the equations (2) and expressing the ratio B/ΣA in percentages,the values in Table 1 are obtained for the percentage differences between areas ΣA and B. When the model‘s parameter s = 1, the obtained no uniformityis equal to 75.2%, at s = 3 the no uniformity is26.3% and at s = 5 it will be 48.6%. Therefore, the best uniformity of the shape of the cells from regularly shaped roughness is obtained when the value s = 3 in pair of equations (1), where the difference between areas ΣA and B has the smallest value. 353 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 2.3. An algorithm for programming the CNC based ball-burnishing operations Contemporary CAM software products haveintegrated modules(or features) which allow to program 2D contour milling operations, using 2D curves for representing the needed toolpath. They can be used for modelling the toolpath for ball-burnishing operation, based on pre-defined two-dimensional curves, by usingsome appropriate mathematical software program (like Mathcad, S-math, etc.)and the pair equations (1)[6]. They have integrated modules for drawing planar or spatial curves based on user defined mathematical functions, orimport them from already existing CAD files. Once they are drawn(or imported from external file), these curves can be set as a tool path, and after that can be post-processedinto NC-code for control the corresponding CNC machine.Therefore, the algorithmforobtaining the appropriate NC-programincludes following four main steps (see Figure 4): 1. Preliminary modelling of the pair of curves in a suitable CAD-CAM system (such as SMath Studio, Solidworks, FeatureCAM, etc.) and adjusting the parameters of the model to obtain relevant shape and dimensions of the cells from regularly shaped roughness; 2. Graphically obtaining suitable curve(s) and export them in an appropriate CAD format that is importable into the CAM software (for example, IGES, DXF, DWG, etc.); Fig.4. An algorithm for creating ball-burnishing operations for 3-axis vertical and 4-axis horizontal CNC- controlled milling centers. 354 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 3. Importing the curves into appropriate CAM software and performing spatial transformations for properly orientation according to the ball-burnishedplanar or cylindrical surface. In this step corresponding rectangular or radial patterns around indexing axis are also defined and all values of the regime parameters of the ball-burnishing operation are set; 4. 3Dsimulation executing for toolpathsverification according to the selected milling operation(s) in the CAM software, and post-processing the NC-code file for the corresponding CNC system. As an output of the purposed algorithm,corresponding ball-burnishingoperations for processinga regularly shaped roughness are obtained on real planar and cylindrical surfaces of machine parts.In present work, the proposed algorithm is performed usingSMath Studio for generating the pair of sinusoidcurves, and FeatureCAM (Autodesk) for programing the toolpaths needed for ball-burnishing operations, both for planar and cylindrical surfaces. Besides these, it is possible to use other existing software products for the same purpose. 3. CONCLUSION Proposed approach for obtaining regular shaped roughness on planar and cylindrical external functional surfaces by using ball-burnishing process, based on presented mathematical equations (1) and the described overall algorithm, shown in Figure 4 has the following major advantages: 1. The ball-burnishing operation can be executed on every 3-axis verticalor 4-axis horizontal CNC milling centres having standard configuration and CNC control system (specified by the equipment manufacturer), without the need to useany additional devices or equipment or any software and hardware modifications in the machine tools; 2. The accuracy of the obtained toolpaths is much better than the accuracy, which can be achieved using manually controlled machine tools. This is due to the fact that here the ball- tool toolpaths are defined by mathematical derived curves, rather than instantaneous values of the regime parameters, as is the case when using manually operated milling machines; 3. The time, needed for calculatingthe curves in SMath Studio, importing andset them as corresponding toolpaths,and post-processing the NC-code using FeatureCAM is within a several minutes, which significantly reduces the preparation time for ball-burnishing process; 4. The possibilities for independent control of the parameters involved in the pair of equations (1),allows precise adjustment of the shape and dimensions of the patterns with regularly shaped roughness; 5. The ball-burnishing operation can be added directly after other machine cutting operations, which allowing the overall operating sequence to be performed on the same machine. The proposed algorithm for generating toolpaths can also be used in performing other metal cutting operations, as well as in other advanced methods for processing of workpieces, such as electrochemical or water jet machining, electro-discharging machining processes, engraving, etc. 355 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 4. REFERENCES: 1. F. Robbe-Valloire, Statistical analysis of asperities on a rough surface, Wear 249 (2001) p.401–408; 2. Georgiev D. S., Slavov S. D., Investigation the influence of regime parameters of flat vibratory burnishing on roughness parameters of flat steel surfaces which have a regular distributed roughness from IV-th type, 2003, journal "Mechanical Engineering and Technologies", TU-Varna and Union of Scientists - Varna, ISSN 1312-0859. 3. Georgiev D.S., Slavov S.D. Mathematical modelling of the trajectory of the deforming element in process of the flat vibratory burnishing, 2-th International Scientific and Technical Conference "Mechanical engineering technologies'99", September 7 - 8, 1999 - Varna, Bulgaria, ISSN 1310 - 8573, p. 11-15. 4. GOST 24773-1981. Surfaces with regular microshape. Classification, parameters and characteristics. 5. J.N. Lee, C.B. Huang, T.C. Chen, Tool-path generation method for four-axis NC machining of helical rotor. AMME, VOLUME 31 ISSUE 2 December, 2008, p. 510-517; 6. Jami J. Shah,Martti Mäntylä, Parametric and Feature-Based CAD/CAM: Concepts, Techniques, and Applications, John Wiley & Sons, ISBN 0-471-00214-3, 1995, 619 pp. 7. Bernard V Liengme, An overview of SMath Suite, 2015 Morgan & Claypool Publishers. 8. Odintsov L. G, Hardening and finishing parts surfaces by plastic deformation, Handbook - Minsk: Engineering, 1987, 328 p. 9. Przybylski W., Technologia obrobki nagniataniem. Warszawa, Wydawnictwa Naukowo-Techniczne, 1987, p 67. 10. Ryzhov EV Technological methods of improving the wear resistance of machine parts, Kiev: Naukova Dumka, 1984, 272 p. 11. Shneider Yu.G. Operational properties of parts with regular microrelief, publishing IVA, St. Petersburg, 2001, ISBN 5-7577-0166-8, 261 p.; 12. Slavov S.D., A laboratory gadget for lay-on a regular micro-relief on the flat surfaces by means of flat vibratory burnishing, proceedings from VI Int. congress AMTECH Sozopol - 2001, Bulgaria, Vol. 2. p. 51 - 56. 356 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X Nr. NAME AND SURNAME, INSTITUTION, E-MAIL crt. 1. ANDRIENKO Sergey Kharkov Nat. Automobile and Highway Univ., Kharkov, Ukraine [email protected] 2. BABIS Claudiu Univ. Politehnica of Bucharest 3. BADEA Delia Nica Constantin Brâncusi University Of Târgu – Jiu, Faculty Of Medical And Behavioral Sciences, 30 Calea Eroilor, 210135, Târgu - Jiu, Romania 4. BĂLTEANU Ancuţa University of Piteşti, Faculty of Mechanics and Technology, Târgu din Vale Street,no.1,Pitești, Romania, [email protected] 5. BÂLDEA Monica University of Pitești,Faculty of Mechanics and Technology,Târgu din Vale Street,no.1,Pitești,Romania, [email protected] 6. BONDARENKO Alexey Nat. Tech. Univ. ―Kharkov Polytech. Inst.‖ 7. BULAC Ion Doctor, University of Pitești, email: [email protected] 8. BURLAN-ROTAR Tudor Polytechnic University of Bucharest, [email protected] 9. BUNECI Mădălina Roxana University Constantin Brâncuşi of Târgu-Jiu, ROMÂNIA 10. CAZALBAȘU Ramona Violeta „Constantin Brâncuşi― University of Tg-Jiu, Faculty of Engineering, 3, Gorj, Romania 11. CĂPĂŢÎNĂ Camelia „Constantin Brâncuşi― University of Tg-Jiu, Faculty of Engineering, 3, Gorj, Romania 12. CHIVU Oana Univ. Politehnica of Bucharest [email protected] 13. CIOFU Florin Engineering Faculty, ‖Constantin Brâncuşi‖ University, [email protected] 357 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 14. CÎRŢÎNĂ Daniela „Constantin Brâncuşi― University of Tg-Jiu, Faculty of Engineering, 3, Gorj, Romania 15. CÎRŢÎNĂ Marius Liviu University ,, Constantin Brancusi‘‘ from Targu-Jiu, [email protected] 16. DIMITRESCU Andrei Univ. Politehnica of Bucharest, [email protected] 17. DOBRESCU R. N. University of Pitesti,1 Targu din Vale St., 110040 – Pitesti [email protected] 18. DRĂGUŢ Gheorghe Constantin Brancusi University of Tg-Jiu, Romania 19. DUMITRU Gabriel Polytechnic University of Bucharest, [email protected] 20. GARASHCHENKO Yaroslav Nat. Tech. Univ. «Kharkov Polytech. Inst.», Kharkov, Ukraine [email protected] 21. GHIMISI Stefan Constantin Brancusi University of Târgu Jiu, [email protected] 22. GUTSALENKO Yury Nat. Tech. Univ. ―Kharkov Polytech. Inst.‖, Kharkov, Ukraine [email protected] 23. IANĂŞI Cătălina ―Constantin Brâncuşi‖ University of Tg-Jiu [email protected] 24. IANCU Cătălin Engineering and Sustainable Development Faculty, ‖C-tin Brâncuşi‖ Univ. of Tg-Jiu, [email protected] 25. IONICI Cristina Constantin Brancusi University of Tg.-Jiu, [email protected] 26. ISTRATE Mihaela University of Pitești,Faculty of Mechanics and Technology,Târgu din Vale Street,no.1,Pitești,Romania, [email protected] 27. ITU Răzvan Bogdan Department of Industrial Mechanical Engineering and Transport, University of Petroșani, [email protected] 358 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 28. ITU Vilhelm Department of Industrial Mechanical Engineering and Transport, University of Petroşani, [email protected] 29. IVKIN Vladislav Nat. Tech. Univ. ―Kharkov Polytech. Inst.‖, Kharkov, Ukraine 30. KLЕNОV Оlеg DiMerus Engineering Ltd., Kharkov, Ukraine [email protected], 31. KOSMARAS Asterios International Hellenic University, Thermi, 57001 Thessaloniki, Greece, [email protected] 32. LUCA Liliana University Constantin Brancusi of Targu-Jiu, [email protected] 33. MATUSHENKO Nicholay Nat. Tech. Univ. ―Kharkov Polytech. Inst.‖ 34. MIHAI C. University of Pitesti, 1 Targu din Vale St., 110040 – Pitesti [email protected] 35. MIHUT Nicoleta-Maria Constantin BrâncuşiUniversity of TgJiu, [email protected] 36. NIOAŢĂ Alin Engineering Faculty, ‖Constantin Brâncuşi‖ University, [email protected] 37. NIŢOI Dan Polytechnic University of Bucharest, [email protected] 38. NOVIKOV Feodor Simon Kuznets Kharkov Nat. Univ. of Economics, Kharkov, Ukraine, [email protected] 39. NOVIKOV Grygoriy Elbor S&T Co., Kharkov, Ukraine [email protected] 40. PANĂ Nicolae Polytechnic University of Bucharest, email: [email protected] 41. PARIS Adrian Stere Univ. Politehnica Bucharest, email: [email protected] 359 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 42. PASĂRE Minodora Constantin Brancusi University of Tg-Jiu, Romania [email protected] 43. PECINGINĂ Irina Ramona „Constantin Brâncuşi‖ University of Tg-Jiu, [email protected] 44. POLYANSKY Vladimir Empire of Metals Ltd., [email protected] 45. POPA N. University of Pitesti, 1 Targu din Vale St., 110040 – Pitesti [email protected] 46. POPA Roxana Gabriela „Constantin Brâncuşi‖ University of Tg-Jiu, 47. POPESCU Constantin Polytechnic University of Bucharest, email: [email protected] 48. PRELIPCEANU Alina Ioana Polytechnic University of Bucharest, [email protected] 49. PROTASOV Roman Nat. Tech. Univ. ―Kharkov Polytech. Inst.‖, [email protected] 50. RĂDULESCU Constanţa University ,, Constantin Brancusi‘‘ from Targu-Jiu, [email protected] 51. ROȘCA-FÂRTAT Gabi Polytechnic University of Bucharest, email: [email protected] 52. RYABENKOV Igor Petro Vasylenko Kharkоv Nat. Tech. Univ. of Agriculture, [email protected] 53. SAVESCU Dan Transilvania University of Brașov, [email protected] 54. SHKURUPY Valentin Simon Kuznets Kharkov Nat. Univ. of Economics, Ukraine [email protected] 55. STAN Marius Universitatea Petrol Gaze din Ploiesti, e-mail: [email protected] 360 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X 56. STĂNCIOIU Alin U.C.B, Tg-Jiu e-mail [email protected] 57. STOYAN Slavov Department of Technology of Machine Tools and Manufacturing, Technical University of Varna, Bulgaria [email protected] 58. TÂRCOLEA Constantin Univ. Politehnica Bucharest, email: [email protected] 59. TZETZIS Dimitrios International Hellenic University, Thermi, 57001 Thessaloniki, Greece, [email protected] 60. YALCINKAYA Senai DepartmentofMechanical Engineering, Facultyof Technology,Marmara University,Kadikoy,34722Istanbul, Turkey,Tel: +905324727900 [email protected] 361 Fiabilitate si Durabilitate - Fiability & Durability No 1/ 2017 Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X