DESIGN AND ANALYSIS OF AN AUTOMOTIVE BRAKE DISC ON THE BASIS OF TEMPERATURE DISTRIBUTION

Abstract

Brakes are the most important safety feature of any vehicle. The current study deals with the temperature analysis of rotors made of different materials used in the front disc brake in APACHE RTR 160 motorbike under severe or hard braking conditions with single stop braking taking into assumption no slip (no locking of wheels) occurring at the tyre ground interface. Single stop braking implies applying the brakes continuously from non zero velocity till the velocity is reduced to zero. If the slip takes place between tyre and ground, then there is some loss of energy between them which will not be dissipated through the brake system. The materials chosen for the disc brake rotor are Grey Cast Iron, Ductile Cast Iron, Aluminium Metal Matrix Composite and Martensitic Stainless Steel. The model is developed using ABAQUS CAE and the dynamic temperature displacement explicit analysis has been performed. The simulation is performed and the results are compared analytically for the solid rotor. The temperature distribution obtained is utilized to find out the best material to be used as the disc material in the front disc considering cost, maximum temperature reached, mass of the disc, heat distribution, temperature distribution, hot spots, temperature gradients etc. Severe braking in emergency braking results in very high rise in temperature due to very short time span of braking resulting in higher braking power and high rate of heat generation with minimum amount of heat transfer taking place in surrounding due to convection and radiation in the braking phase. In the present work, heat transfer due to radiation is neglected. Most of the braking power generated due to friction in severe braking is almost absorbed into the disc brake system. The thermal energy is mainly absorbed by the disc surface and pad surface in contact, and due to conduction it gets distributed to the pad, disc and to vi components which are in contact with them. This also puts a need to verify whether the brake system material and different components would be able to bear such fast rise in temperature without failure. The analysis is based on the energy conservation principle i.e. the energy possessed by the vehicle during the start of braking phase must almost be (taking 97%) absorbed in the disc brake system in the severe braking conditions with minimum heat loss taking place in surrounding due to very less time of braking. In the present work, total kinetic energy of the vehicle is provided as the rotational energy to the disc brake system using some design changes. This rotational energy is now dissipated in the form of heat energy due to real friction contact between the pad and the disc. The heat energy dissipated is distributed between the disc and the pad depending on the material properties of the disc and pad like mainly on thermal conductivity, density, specific heat and thermal diffusivity. In general, 90-95% of heat energy goes to the disc surface. The friction pad material has been kept same for different discs. It has been found out that the maximum temperature occurs in the frictional contact region of the disc and pad. The temperature is higher on the surface of the disc as compared to the inner portions. On the surface of frictional contact region of disc, the temperature increases to a maximum value and then decreases with braking time. Saw-tooth variation of temperature with respect to time is observed in the contact region nodes which is similar to the experimental results.