A study of thermal and mechanical behaviour for the optimal design of automotive disc brakes

Abstract

The thermal distortion induced by thermoelastic instability (TEI) results in hot spots on the surface of the brake disc. This can incur low-frequency vibration known as judder. In pad-induced squeal noise, mode coupling occurs owing to the variation in the friction coefficient between the disc and pad, inducing high-frequency noise. Through a coupled analysis of hot spots and squeal phenomena, an optimum disc and pad design can be designed for higher thermal and mechanical performance. In this study, numerical and experimental analyses are performed in accordance with disc thickness, pressurization type of caliper, and lining arc length, considering thermal and mechanical instability simultaneously. Thermal deformation and pressure distribution are calculated using a finite element analysis (FEA). For evaluating TEI performance, experiments are performed using a chassis dynamometer and a high-speed infrared camera, and the results are correlated with FEA results. A complex eigenvalue analysis is conducted to evaluate mechanical instability using an FEA. Modal testing and simulations are conducted to correlate a real model and an FE model, and the corrected simulation results are applied for a complex eigenvalue problem to analyse coupled modes according to rotor and pad shapes. The results on disc brake performances considering the disc and pad design are discussed in terms of hot spots and squeal problems.