Effects of Thermal Deformations on the Squeal Propensity of a Simple Automotive Disc Brake System

Brake squeal has been found to be related to varying temperatures. In order to investigate this problem, the finite element method is applied to a disc brake system. Thermal analysis is incorporated to assist complex eigenvalue analysis to extract unstable modes which may contribute to squealing phenomena over a series of discrete temperatures. The SAE J2521 test sequence is simulated to predict the temperature variations on the whole three dimensional geometry of the brake pads and the disc, during the prescribed drag braking situations. This coupled thermal structural analysis considers different stages of the drag brake event, particularly the difference in the temperature distribution and consequent contact status during the heating and cooling stages. The coupled analysis leads to the prediction of squealing instability measures and frequency spectra.

A series of iterations of these sequentially coupled analyses was performed in order to study the influence of various parameters on the propensity for squeal. From these analyses, instability measures were used to predict the squealing propensity, and also their respective frequencies were found. The coefficient of friction, brake pressure, elastic modulus and the thermal expansion coefficient of the brake pad material were considered in this parametric sensitivity study.