During a vehicle's braking action, a wheel's kinetic energy is transformed into heat, which doesn't dissipate fast enough into the air stream from the brake to the brake disk. Thus, one of a disk brake's material properties — thermal conductivity — plays a critical role. In addition, thermal judder results from non-uniform contact cycles between the pad and the disk brake rotor, which is primarily an effect of the localized thermoelastic instabilities (TEI) at the disk brake's rotor surface. Localized TEI can generate intermittent hot bands around the rubbing path.

The mechanism of the TEI phenomena has been of interest to many researchers, but this study assumes the thermomechanical phenomenon of each disk is in symmetry about the disk's midplane. It also assumes that the wear taking place during the braking process resulting from the friction between the disk brake and the pad is negligible. This study examines the transient analysis of the thermoelastic contact problem for disk brakes with frictional heat generation using COMSOL Multiphysics finite element analysis (FEA) software. The model simulates the braking action by investigating both the thermal and elastic actions occurring during the friction between the two sliding surfaces (the disk brake and the pad).

Figure 1: 3D Temperature Distribution for a disk brake during a time span of 10 s.
The FEA simulation intended to improve the conceptual design of the disk brakes is divided into two parts: thermal and elastic. During the analysis, the braking parameters are set to certain values based on those in the literature. These parameters include the brake's rotational speed and the cycle of the applied pressure. During the braking process it is assumed that the pressure first increases linearly until it reaches the maximum value within 2.5 s, then the pressure remains constant for another 1.5 s, and finally drops to zero.