A disc-pad system is established to study impacts of surface topography on brake squeal from the perspective of statistical analysis. Firstly, surface topographies of brake disc and pad are precisely measured on the scale of micron and are statistically analyzed with a three-dimensional evaluation system. Secondly, a finite element model of brake disc and pad without surface topographies is created and verified through component free-modal tests. Thereby the valid brake squeal complex-modal analysis model is built with ABAQUS. An effective method is developed for applying interface topographies to the aforesaid smooth contact model, which consequently establishes sixty brake squeal models with topographies. Thirdly, impacts of surface topography on brake squeal are studied through comparison and statistical analysis of prediction results with and without topographies.

The analysis manifest that topography amplitudes and evaluation index deviations of brake pad far exceed those of the disc, indicating the surface of brake pad is relatively much rougher. Moreover, squeal prediction results confirm that surface topographies can both cause contact pressure variation and affect the randomness of brake squeal characteristics, namely, numbers and values of squeal frequencies. Additionally, contact interface topographies can cause the change of system modal coupling states, which can further affect the squeal tendency and uncertainty. Meanwhile, statistical characteristics and variations of surface topographies demonstrate close correlation with those of brake squeals. Hence the consideration of surface topographies can effectively improve squeal prediction precision, and stochastic characteristic of brake squeal during tests can be well-justified by the time-varying surface topography.

Meng, Huang - Shanghai General Motors Co., Ltd