Friction Phenomena Related to Drum Brake Squeal Instabilities

Abstract

Abstract Several experiments and analyses have carried out in the field of brake squeal and there are many suggestions to be found in the literature as to the cause of brake squeal. In this paper a mathematical model for friction-induced vibration and noise generation is used to study the influence of these different squeal excitation types. Squealing brakes are excited by the friction forces in the interface between the drum and the linings. This friction and its interaction with the brake structure can be modeled in many different ways. In this paper, different self-excitation types identified in the literature are tested — each one having the potential of generating instabilities. The drum brake model used for the analysis is two-dimensional, and consists of a drum and two shoes with linings. The same brake geometry and material properties are used for all computations, which means that the influence of each mechanism can be estimated. The results from this analysis show that, among the friction models analyzed, the constant coefficient of friction model gives the largest contribution to the instability level of squealing drum brakes. The contribution from the negative μ-velocity slope is shown to be minor. For the constant coefficient of friction model, there are different excitation types. Among these, lining deformation induced instabilities are shown to generate large instabilities, follower forces show a negligible contribution to the instabilities generated and self-locking is shown to be impossible for the brake analyzed.