Abstract
ABSTRACT
Automotive brake squeal is an annoying high-pitched sound due to the vibration induced by friction between brake disc and pads. Friction coefficient, as one of the main contributions for brake squeal, depends not only on roughness of contact surface, physical and chemical properties of brake disc and pad, contact characteristics, but also on braking conditions, such as brake pressure, velocity, temperature and so on. Research on friction dynamics to establish proper friction models is helpful for getting better understanding of the mechanisms of brake squeal generation, evolution and supression. In this paper, the friction experiments are conducted on a pin-disc friction testing machine. The instantaneous friction coefficient and surface temperature of the disc are measured and analyzed for different pressure and velocity cases. The dynamic friction model are obtained based on the dynamic equilibrium of the increase or decrease of contact area. The experiment results and theory analysis both show that the instantaneous friction coefficient and surface temperature are both the approximate saturation function of time. Then the undetermined coefficients of the dynamic friction model are identified through the experimental data, and its applicable conditions are discussed. Within the applicable scope, the conclusions are achieved that the stationary temperature is proportional to the contact pressure and relative velocity, but the stationary friction coefficient has a negative slope relation with contact pressure or relative velocity.