Effect of the Material Parameter and Shape of Brake Pads on Friction-Induced Disc Brake Squeal of a Railway Vehicle

Abstract

To study the mechanism of brake squeal of light-rail trains, a field test and a simulation analysis of disc brake squeal were carried out. In the field test measurement, the noise and vibration characteristics of brake components under normal braking and abnormal braking were analyzed. The test results show that the peaks of the frequency spectrum of the squeal noise and brake pad vibration correspond. The occurrence of brake squeal is closely related to the abnormal vibration of the pads. According to the theory of friction self-excited vibration, a finite-element model of the disc brake system of the light-rail trains was established. Effects of the material parameters and shape of the brake pad on the tendency for brake squeal were studied using complex eigenvalue analysis. The simulation results show that increasing the Young's modulus of the brake pads can effectively suppress brake squeal, but a larger or smaller Poisson's ratio of the brake pads was not conducive to suppressing brake squeal. Changing the shape of the brake pad will lead to differences in the number, frequency, and instability of unstable modes. It is observed that the shape of the brake pad has a significant effect on suppressing brake squeal. The grooved pad has a better effect in suppressing brake squeal.