Disc-Pad Interaction Related to Brake Squeal

The objective of this paper is to investigate the influence of the non-linearity and time dependence of friction force between disc and pads on the generation of low and high frequency squeal. For this purpose, a non-linear mathematical model of a disc-pad system, that includes the transverse (out-of-plane) and circumferential (in-plane) motions, is developed. The contact normal pressure includes a non-uniform distribution and is represented by a non-linear function of the relative displacement (penetration) of the disc and pad. Friction is assumed as a distributed follower-type force nonlinearly dependent on the relative velocity. Deterministic and random friction coefficient is considered. Numerical simulations reveal a modulated-intermittent response of both disc and pad. It is found that the frequency component corresponding to circumferential vibrations of the disc is always dominant in the case of deterministic friction. However, random friction creates impulsive forces that excite the transverse mode and has little effect on circumferential vibrations.