International Journal of Mechanical Engineering and Technology (IJMET) Volume 8, Issue 7, July 2017, pp. 267–274, Article ID: IJMET_08_07_031 Available online at http://iaeme.com/Home/issue/IJMET?Volume=8&Issue=7 ISSN Print: 0976-6340 and ISSN Online: 0976-6359

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DESIGN AND ANALYSIS OF MULTI CALIPER DISC

G.V.R. Seshagiri Rao Associate professors, Mechanical Engineering Department, Institute of Aeronautical Engineering, Dundigal, Hyderabad-500043, India

G. Naveen Kumar Associate professors, Mechanical Engineering Department, Institute of Aeronautical Engineering, Dundigal, Hyderabad-500043, India

B. Prashanth Assistant professor, Mechanical Engineering Department, MLR Institute of Technology, Dundigal, Hyderabad-500043, India

D.V.Ramana Reddy Associate Professor, Mechanical Engineering Department, Vardhaman college of Engineering, Shamshabad, Hyderabad, India

ABSTRACT In this paper “Eddy current Multi Caliper ” uses the eddy currents generated by the influence on the disc to retard the rotating disc. The trends of the braking torque are observed by varying various parameters like angular velocity, disc rotor thickness, strength etc. that could affect the eddy current braking. This is further studied using experimentation and is further optimized. The brake, includes Conventional braking also, improving the chances of eddy current braking. Several other improvements are included of the Split brake master cylinder, usage of Floating calipers etc. With the help of permanent magnets and the disc rotor being aluminium this can be used to generated currents with low power. But in large scale uses this has large scope. This paper deals with Design and fabrication of the eddy current multi caliper brake exclusively for the two wheeler . This Brake is a combination of Foucault brake and a Conventional disc brake. This has both the advantages of an Eddy current brake and a disc brake. Key words: Disc Brake, Thermal Analysis, Eddy Current Cite this Article: G.V.R. Seshagiri Rao, G. Naveen Kumar, B. Prashanth and D.V.Ramana Reddy, Design and Analysis of Eddy Current Multi Caliper Disc Brake. International Journal of Mechanical Engineering and Technology, 8(7), 2017, pp. 267– 274. http://iaeme.com/Home/issue/IJMET?Volume=8&Issue=7

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1. INTRODUCTION The Disc brake is a wheel brake which moderates the revolution of the wheel by the erosion caused by pushing brake cushions against a brake plate with an arrangement of calipers as appeared in Fig.1.0 A brake is a mechanical device that hinders the movement by retaining energy from a moving framework. It is utilized for reduction or ceasing a moving , wheel, hub, or to keep its movement, frequently achieved by methods for friction. Most generally utilize friction between two surfaces squeezed together to change over the dynamic energy of the moving article into heat, however different strategies for energy transformation might be utilized. For instance, regenerative braking changes over a significant part of the energy to electrical energy, which might be put away for later utilize. Different techniques change over dynamic energy into potential energy put away in such structures as pressurized air or pressurized oil. Vortex current brakes utilize attractive fields to change over dynamic vitality into in the brake plate, blade, or rail, which is changed over into heat. Still other braking methods, even change motor vitality into various structures, for instance by exchanging the vitality to a turning flywheel. Brakes are for the most part connected to pivoting axles or wheels, however may likewise take different structures, for example, the surface of a moving liquid (folds sent into water or air). A few vehicles utilize a mix of braking components, for example, racing autos with both wheel brakes and a parachute, or planes with both wheel brakes and folds raised into the air amid landing. At the point when the brake pedal of an advanced vehicle with water driven brakes is pushed against the ace barrel, at last a cylinder pushes the brake cushion against the brake circle which backs the wheel off. On the brake drum it is comparable as the chamber pushes the brake shoes against the drum which additionally moderates the wheel down. Fig 2.0 demonstrates the design of disc brake. Electromagnetic brakes are in like manner regularly utilized where an electric engine is as of now part of the hardware. For instance, numerous half breed fuel/electric vehicles utilize the electric engine as a generator to charge electric batteries and furthermore as a . Electromagnetic brakes moderate a protest through electromagnetic enlistment, which makes resistance and thusly either warmth or power.

Figure 1.0 Disc brake Figure 2.0 Disc brake layout

Brake Caliper The brake caliper is the gathering which houses the brake cushions and cylinders. The cylinders are typically made of aluminum or chromed steel. Calipers are of two sorts, drifting or settled as appeared in figure 3.0. A settled caliper does not move in respect to the plate and is in this way less tolerant of circle flaws. It utilizes at least one sets of restricting cylinders to brace from each side of the plate, and is more mind boggling and costly than a skimming caliper.

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A skimming caliper (likewise called a "sliding caliper") moves regarding the circle, along a line parallel to the hub of revolution of the plate; a cylinder on one side of the circle pushes the internal brake cushion until it reaches the braking surface, at that point pulls the caliper body with the external brake cushion so weight is connected to both sides of the circle. In 2001, An eddy current reduction apparatus was designed by Tohru Kuwahara “An eddy current reduction braking system in which with high speed rotation of a brake drum, produced by magnets is concentrated to increase magnetic flux density and thereby enhance braking force. According to the invention, there is provided a guide tube formed of a non-magnetic material and having a hollow portion in the shape of a rectangle in section disposed interiorly of a brake drum. A number of ferromagnetic pole pieces are disposed at annularly equal intervals on an outer surface of the guide tube and at least one support tube is movably mounted in the hollow portion of the guide tube. Magnets are mounted on the magnet support tube such that their polarities with respect to the ferromagnetic pole pieces are alternately different.” In 2002, Jeremie Lagarrigue invented and published systeme de freinage a disque multipistons and explained it as “The invention concerns a multiple-piston disc brake system, consisting of a double calliper equipped with two sets of six pistons diametrically opposite relative to the axis of rotation, and a disc comprising two concentric tracks, the pistons of each set, opposite in sets of three on either side of the disc, being arranged such that two pistons act on the inner track and twice two pistons act on the outer track, a metering valve enabling to delay the action of the two tracks. The invention generally concerns the industrial and commercial field of the manufacture and distribution of braking equipment adaptable on all rotating systems, but particularly designed for motorcycles and in particular powerful and fast motorcycles such as racing motorcycles.” In 2014, Christopher James Allington described his Braking mechanism as “An eddy- current braking mechanism including a rotor, rotatable about a rotor axis; at least one electrically conductive member coupled to the rotor for rotation therewith; at least one magnet configured to apply a magnetic field extending at least partially orthogonal to the plane of rotation of the conductive member, and characterized in that upon rotation of the rotor, the conductive member is configured to move at least partially radially from the rotor axis into the applied magnetic field.”

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2. EDDY CURRENT MULTI CALIPER BRAKE These brakes use the principles of both Eddy current brakes and Disc Brake i.e., this is a simple yet elegant combination of the eddy current brake and a conventional Friction Disc brake. This is a simple construction of an eddy current brake embedded in a disc brake for a functional piece of braking tech in the Modern day automobiles. The construction is similar to that of a disc brake, this contains a disc rotor, brake caliper and hydraulic mechanism but with a slight change in materials and their actuation with a few additional parts. The disc rotor material is considered to be an aluminium alloy and additionally two more Calipers are arranged over the disc that accommodate the permanent magnets. The two Calipers are actuated initially which function as an eddy current brakes and the third caliper is equipped with a general brake pad which functions as a conventional disc brake caliper. Thus this is named as “Eddy Current Multi Caliper Brake”.

3. DESIGN AND CALCULATION OF DISC BRAKE Designed Eddy current Disc brake model using creo software and carry out the finite element analysis (FEA) using ANSYS 14.5. Thus we obtained the values of shear stress, total deformation, and convective heat transfer coefficient and temperature distribution on disc brake. Figure 4 shows the meshed model of disc brake for Thermal analysis .For analysis disc brake was meshed using triangular surface meshes. The model is mashed and analyzed to get the result of contact zone (disc-pad). This is very important because in this zone the temperature rises considerably.

Figure 4 Meshed model of Disc Brake

Table 1 shows the Dimensions of Disc brake

Disc outer Diameter 190 mm Disc inner Diameter 127mm Disc Thickness 5 mm Calliper piston diameter 29.21mm Area of master cylinder 314.15mm2 Coefficient of friction 0.3 Weight distribution 60% to rear 40% to front Static rolling radius front tyre 842.6mm Static rolling radius rear tyre 766.04mm Coefficient of friction of road and tyre 0.7 Brake torque 79.2 N-m Braking effort 100 N Deceleration 6.86 ms-2

Vehicle speed 60km/hr Stopping distance 9.247m Stopping time 2.32 sec

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4. CALCULATIONS Mass of vehicle = 225 kg Velocity of vehicle = 16.66 m/s Kinetic Energy = ½ *M*V2 =31225.005 Joules Kinetic energy = Thermal Energy absorbed by brakes Heat flux = Thermal Energy/ 2 * Area of rubbing surface = 998241.84 W/m2 Braking Efficiency is 60:40 for front and rear so heat flux=998241.84*.6 =598945.108 W/m2

5. SELECTION OF MATERIAL Using the analysis done on various materials with varying parameters theoretically, we can determine that the best materials suitable for disc material are Tungsten, Titanium and Aluminium. This result is also predicted initially using the density to specific conductivity ratio. Keeping in mind the cost of the materials and availability we short listed the materials from those to Aluminium, because aluminium is cheap of cost and is abundance. The added advantages of easy machinability improve over choosing of material. Even though Titanium and Tungsten are very good materials to conduct the project with but The graphical data does not prove then to be a better material for conducting the experimentation, their availability is limited to tool bits and casted shapes. These materials can be applied for further applications. They give advantages over Aluminium in several aspects like strength, stress concentration, thermal and electrical conductivity etc. even though bearing various disadvantages as machining, material cost and others.

6. BRAKING TORQUE OF DISC BRAKE When brake is applied using the brake pedal the brake pad engages and results in a stopping force tangentially the total force excreted and the braking torque generated is proportional to the rotor disc area and the brake pad area because this f=gives the frictional area for brakes to be applied. This braking effort results in converting the mechanical energy into heat energy resulting in reading or stopping the vehicle. The disc rotor material in our project needs to sustain a very low speeds and low forces as most of the braking at high speeds is carried away by the eddy current braking segment of the brake. Assumed values and parameters are as follows. Rotor Disc diameter (2R) = 280mm Rotor disc material = Aluminium Pad brake area (Ad) = 700mm2 Pad material = Asbestos Coefficient of friction (Wet) = 0.07-0.13 Coefficient of friction (Dry) = 0.3-0.6 Maximum Temperature (Tmax) = 350˚C Maximum Pressure (Pmax) = 1Mpa Normal Force at inner face (Ni) Ni= µi FRI Eq. 6.1

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Where µi =Coefficient of friction=0.5 FRI= Pa X Pmax /2 Ni = (0.5)(0.5)(700 x 106) Ni = 175 N = No (Normal Force at inner face) Braking Torque (TB) TB= FR Eq. 6.2 F = Total Force = Ni + No = 350 N R = Radius of rotor = 140 x 10-3 mm TB= (350)(140 x 10-3) = 49 Nm

7. HEAT GENERATED BY DISC BRAKE When brake is applied using the brake pedal the brake pad engages and results in a stopping force tangentially the total force excreted and the braking torque generated is proportional to the rotor disc area and the brake pad area because this f=gives the frictional area for brakes to be applied. The engagement of the disc rotor and the brake pad results in generation of heat which can be given by the equation as follows Heat Generated Q = mCpΔT m = mass of disc = 0.7 kg Cp = Specific heat capacity = 800 J/Kg˚C ΔT = Temperature difference = 15˚C Eq. 6.3 Q = mCpΔT = (0.7)(800)(15) =8400J Disc area (Ad)= (R2-r2) = ((0.14)2-(0.06)2) = 0.0503m2 Heat Flux (q) = Q/A = 8400/0.0503 = 33.42 KW/m2 Thermal Conductivity (k) of disc material (Iron) = 205 W/mk Thermal gradient = Heat Flux(q)/ Thermal Conductivity (k) Eq.6.4 = 33422/205 = 163 m/k

8. HEAT GENERATED BY EDDY CURRENTS Eddy currents generate resistive losses that alter a few types of electricity, consisting of kinetic power, into heat. In transformer, we deliver alternating present day in the number one, this alternating current produces alternating magnetizing flux inside the center and as this flux hyperlinks with secondary winding, there will be brought about voltage in secondary, ensuing present day to float thru the burden connected with it. a number of the alternating fluxes of transformer; may additionally hyperlink with other undertaking components like metallic center or iron frame of transformer and many others. As alternating flux hyperlinks with those elements of transformer, there would be a locally brought about εmf. due to those εmf, there would be currents so that you can flow into locally at that parts of the transformer. These circulating current will not contribute in output of the transformer and dissipated as heat. This type of energy loss is called eddy current loss of transformer. But in this brake we use these eddy currents as braking parameters so the heat generated by these eddy currents are also to be considered experimentally.

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9. RESULTS & CONCLUSIONS

9.1. RESULTS By comparing the results of both the experimental and analytical analysis, it was sure that the pattern of graphs and values predict up to some extent. There is a limitation to this eddy current brake, this cannot work under low speeds. According to analytical analysis the eddy current brake functions at low speeds but ineffectively. Reviewing at the value from the experimental analysis this is completely wrong, the eddy current brake doesn’t work at all at lower speed. The use of conventional friction caliper helps to eradicate this problem completely. Even though the observations are almost similar to others, there is an error experimental analysis shows that the eddy current brake is effected by several other conditions like Local weather, Temperature, Surrounding Magnetic or electromagnetic equipment, Vibrations in the body, Magnets losing their Magnetic properties at high temperatures. The Air being a bad conductor of electricity reduced the induction of eddy currents and generation of opposing magnetic field. So the air gap is optimised to maximum extent possible to the attained equipment. The area of the magnet is further increased by adding more magnets on to the brake pads which in turn increased the surface area effected by the magnetic field generating more and more eddy currents. But there is a problem of heat dissipation when a disc is completely enclosed by set of calipers. Several other modifications of minute terms are made for the prototype to actually function which are listed in this report. The Eddy current multi caliper brake will function as predicted for other materials but the factors effecting the braking are also to be minimized. This eddy Current multi caliper brake is designed for a motor bike, because a completely functioning eddy current brake for cars is already developed which is sealed type eddy current brake. This concealing of the brake cannot be done in two wheelers due to their less body and space in the bike chassis. The error is calculated as follows based on Angular velocity %error= (Analtyical- Actual)/ Analytical x 100 =1.58-1.27/1.58 x 100 =19.6%

9.2. CONCLUSION The Eddy Current Multi Caliper Brake consists of both the advantages and frictional disc brake and Eddy Current brake. The Brake is further modified with optimised materials like Aluminium alloys and Tungsten Alloys. The Tungsten alloys show the required properties of an eddy current brake and satisfy the forces seen in a disc brake. These materials can be implemented to commercial use. Several other factors affecting the braking can also be minimised by using than permanent magnets. These can help the actuation of brake with ease when compared to that of a complicated hydraulic actuated disc brake.

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[1] Abd Rahim Abu Baker, Huajiang OuyangPrediction of Disc Brake Contact Pressure Distributions by Finite Element Analysis Jurnal Teknologi 43(A) Dis. 2005: 2136 © Universiti Teknologi Malaysia [2] M. Nouby, D. Mathivanan, K. Srinivasan, A combined approach of complex eigenvalue analysis and design of experiments (DOE) to study disc brake squeal International Journal of Engineering, Science and Technology Vol. 1, No. 1, 2009, pp. 254-271 [3] Huajiang Ouyang, Wayne Nack, Yongbin Yuan, Frank Chen, Numerical analysis of automotive disc brake squeal, Int. J. Vehicle Noise and Vibration, Vol. 1, Nos. 3/4, 2005 [4] Hudson, M., Ruhl, R., Ventilated brake rotor air flow investigation, SAE Technical Paper 971033, 1997. [5] Wallis, L., Leonardi, E., Milton, B., Air flow and heat transfer in ventilated disc brake rotors with diamond and tear-drop pillars, Proceedings of International Symposium on Advances in Computational Heat Transfer, Australia, 2002, pp. 643–65 [6] Choi, B. K., Park, J. H., Kim, M. R., Simulation of the braking condition of vehicle for evaluating thermal performance of disc brake, Proceedings of KSAE Autumn Conference, 2008, pp. 1 265–1 274. [7] Jacobsson, H., Aspects of disc brake judder, Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 217 (6) (2003) 419–430. [8] Jung, S. P., Park, T. W., Kim, Y. G., A study on thermal characteristic analysis and shape optimization of a ventilated disc, International Journal of Precision Engineering and Manufacturing 13 (1) (2012) 57–63. [9] V. Saritha and Vinayak G. Kachare, Finite Element Analysis of Disc Brake Rotor Using Different Materials. International Journal of Mechanical Engineering and Technology, 7(6), 2016, pp. 410–416. [10] R. Ramesh Kumar and V. Thiruvengadam and J. Thamilarasan. Manufacturing and Force Determination of Composite Disc Brake. International Journal of Mechanical Engineering and Technology, 8(2), 2017, pp. 246–255. [11] Amol A. Apte and H. Ravi, “FE Prediction of Thermal Performance and Stresses in a Disc Brake System,” SAE Technical Paper, 2006-01-3558. [12] M. Rama Narasimha Reddy, K.Harshavardhan Reddy, N.Balaji Ganesh, “Design, Structural and Thermal Analysis & Disc Brake. IJFSET 2013.

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