Insight into brake squeal source mechanism considering kinematic nonlinearity and pad-disc separation

The chief goal of this study is to propose an improved mathematical model for the brake squeal phenomenon, a dynamic instability problem seen in vehicle brake systems. Accordingly, a three degree of freedom model of the brake pad is developed that is initially in contact with the brake disc. In this model, the pad has two translational and one rotational degrees of freedom and unlike prior formulations, its leading and trailing edges are defined. The governing equations include kinematic nonlinearities (arising from the arrangement of the braking force vectors) and separation effects between the pad and the disc. These equations are numerically solved for a few braking force vector arrangements, and the resulting dynamic responses are compared for several cases. The importance of pad-disc separation is better understood with the proposed model. In conclusion, an improved insight for the brake squeal source mechanisms is obtained while overcoming the limitation of prior models.