Estimation of Vibration Response of Reciprocating Engine Crankshaft Dipak Gulhane1, Dr.G.D.Mehta2, Prof.S.M.Awatade3
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International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 03 Issue: 10 | Oct-2016 www.irjet.net p-ISSN: 2395-0072 Estimation of Vibration Response of Reciprocating Engine Crankshaft Dipak Gulhane1, Dr.G.D.Mehta2, Prof.S.M.Awatade3 1Student, Dept. of Mechanical Engineering, Priyadarshini College of Engineering, Nagpur, Maharashtra, India [email protected] 2Associate Professor, Dept. of Mechanical Engineering, Priyadarshini College of Engineering, Nagpur, Maharashtra, India 3Assistant Professor, Dept. of Mechanical Engineering, Priyadarshini College of Engineering, Nagpur, Maharashtra, India ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract - Most of the people hear the word “crankshaft,” study of the crankshaft are related with the way that the they imagine it as a main part of the engine, which also crankshaft wraps around the bearing, forming a continuous consists of parts like slider crank, connecting rod, and piston. rotation. This effect is called the reciprocating into rotary, Crank shaft is an important part of engine used to transmit together with the impact between crank and crankshafts reciprocating motion into rotary motion. Crank shaft is participates in the creation of the noise and vibrations on the designed according to number of cylinders used for fuel engine and to determine the crankshaft load capacity and its combustion. Strokes of cylinders are so adjusted that forces service life. acting is simultaneous on crankshaft. According to studies Crankshaft is extensively used in automobile industries. It is most engine failures are occurred due to failure of crankshaft. seen that it is used right from small capacity machine to Failures of crankshaft are due to many reasons such as fatigue heavy capacity machine. During machine operation the failure, failures due to vibration, etc. All machines in the world crankshaft receives variable load and thus induces variable have some sort of vibrations. But most important factor for tension in it. The linkage member of a crank experiences this failure of any machinery is because of vibration. Vibration varying tension during complete work cycle. Evidences says generated in crankshaft may be responsible for failure of that due to this varying load condition the crank itself engine. If vibrations generated are more than allowable vibrates which provides impact loads on its bearing and thus vibration, engine tends to fail. Vibration monitoring of it enhances the wear and tear of a crank. Hence it is crankshaft is very difficult. There are many methods to find inevitable to see the effect of varying load condition of a vibration in crankshaft such as analytical, mathematical, specific unit on its performance by estimating its vibration. graphical, by use of software i.e. by ANSYS, CATIA, and NASTRAN etc. This software’s are used to crosscheck and to 2. FORMULATION OF PRESENT WORK find critical observations which are difficult to find by analytical methods in mechanical parts. With reference to the literature review and past work This research is genuine attempt to find out effects of vibration done by various researchers, we find that crankshaft plays a produced inside the engine on crankshaft and its effect on very crucial role in energy as well as motion transfer. So, it is performance of engine. The process used to find out vibration required to study its dynamic behavior in working condition. response of reciprocating engine crankshaft is by making Owing to the complexity and construction of its geometry the graphical investigation of various forces produced in the analysis of crankshaft is very difficult to carry out by engine parts and its effect on crankshaft. The stresses analytical means and therefore we find software based generated on crankshaft are calculated using ANSYS which approaches in all the researches to analyze the dynamic behavior of the crankshaft. There are many software like gives detailed information about vibration response of CATIA, HYPERMESH, ANSYS etc. used for analyzing the crankshaft component against development of stresses, strains etc. and clearly gives an idea about the fatigue life cycle of the Key Words: Crankshaft, Engine, Vibration response, component being tested. But still software based approaches MatLab, finds limitation in giving an exact statement of values of the parameters against which the component is going to work and hence, it is difficult to ascertain the life span of the 1. INTRODUCTION component or mention the particular cause of its failure. In fact results obtained from the software relay on the Crankshaft dynamics became the interest to the automobile computation done with the help of programs which is fed industry with the rise in importance of noise, vibration & manually by a programmer. The software only shows results harshness (NVH). Vibration and noises generated by crank stored in the memory and it has no relation with practical transmission during the high speed application is the main situation. problem of dynamic research. The major difficulties in the © 2016, IRJET | Impact Factor value: 4.45 | ISO 9001:2008 Certified Journal | Page 1251 International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 03 Issue: 10 | Oct-2016 www.irjet.net p-ISSN: 2395-0072 So, we can say that analytical means is equally important 4. Dynamic Analysis of Slider Crank Mechanism as software based approaches. But the result obtained by analytical means is limited by the number of variables taken The dynamic behavior of crankshaft of a reciprocating into account and in turn to get the exact solution of the engine has been explained. For the analysis purpose the problem. reciprocating engine is modeled as a simplified slider crank A general procedure for the analysis of the component is arrangement where cylinder, crank, connecting rod and given below: piston of the reciprocating engine is represented as link 1, link 2, link 3 and link 4 in slider crank arrangement 1. Obtaining detailed dimensions of the component to respectively [refer figure 1.1] and their center of gravity is be tested. assumed to be concentrated at the center of respective links. 2. Creating a model using any of modeling software like Creo.2 parametric, CATIA, and Solid Edge etc. 3. Saving the file of the model created so that it can be imported to analysis software, ANSYS, Unigraphics etc. 4. Opening the file in Analysis software [ANSYS] for performing static analysis [using dynamic forces as input] and model analysis [vibration]. 5. Applying meshing condition. This is an important step because difference between exact solution and approximate solution depend upon the type of meshing we choose. 6. Obtaining the value of stress, strain, natural frequency, mode shapes etc. Fig -1: Schematic diagram of slider crank A. Estimation of forces on links 3. AN APPROACH FOR VIBRATION ANALYSIS OF The analysis is initiated by considering position shown in MODEL figure 1.1 as the reference position where angular position of As there different techniques available for performing link 2 is 360 with respect to link 1 at this instant. With vibration analysis of a model however, the stepwise reference to this position, the crank is rotated in procedure of the methodology used in the present research is anticlockwise direction with an angular displacement of 360 discussed below: and therefore dynamic analysis is carried out at 360, 1080, 2520, 3240, 3960, 4680, 6120, and 6840. 1. The physical system [engine] is converted into a simplified dynamic model. The dynamic model is a Since all the links of the mechanism are moving with some slider crank chain where center of gravity of each velocity and acceleration, the inertial forces associated with component of the engine is assumed to be the links cannot be ignored. So, it is required to perform a concentrated at the geometric center. kinematic analysis of the links at every angular position mentioned above. The table4.1 and table 4.2 shows all the 2. Kinematic analysis is performed graphically for the calculated values of velocity and acceleration and a graph model under which velocity and accelerations of has been plotted for the same [shown in figure.1.2 & 2.3] center of gravity of each links have been estimated. Table 1: Calculation for velocity 3. After kinematic analysis of the model, it is considered for dynamic analysis according to law Θ V2 V3 V4 proposed by DE ‘Alembert. According to which a 36 94.24 81.66 84.84 dynamic case can be considered as a static case 108 94.24 31.41 78.52 when inertia forces due to acceleration associated 252 94.24 34.55 75.38 with the link is considered on the link. 324 94.24 81.84 84.80 4. A load Torque on crankshaft of the engine is 396 94.24 81.66 84.84 calculated for mentioned crank rotation. 468 94.24 31.41 78.52 612 94.24 34.55 75.38 Finally the calculated load torque is used for estimation of 684 94.24 81.84 84.80 torsional amplitudes of shaft under torsional vibration. © 2016, IRJET | Impact Factor value: 4.45 | ISO 9001:2008 Certified Journal | Page 1252 International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 03 Issue: 10 | Oct-2016 www.irjet.net p-ISSN: 2395-0072 Figure 4.2 shows a dynamic analysis of slider crank mechanism at θ=1080. In this figure we have focused on the forces acting on the connecting rod, crank and slider. These forces are denoted by FP, F14, Fi4, FW, F34, Fi3, F23, Fi2, where, FP is a pressure force acting on slider or piston due to power stroke at point C, F14is a force due to normal reaction from cylindrical wall, Fi4 is the inertia force due to movement of slider, FW is a force due to weight of the slider, and F34 is a force due to link 3 on the link 4 i.e.