Incorporation of Friction Material Surface Inhomogeneity in Complex Eigenvalue Analysis to Improve the Accuracy of Brake Squeal Analysis

The sliding surface of the brake friction material is not uniform but composed of random contact plateaus with a broad pressure distribution, which are known to closely related to the triggering mechanism of friction induced noise and vibrations. The non-uniform contact plateaus are attributed to the various ingredients in the friction material with a broad range of physical properties and morphology and the size and stiffness of the plateau play crucial roles in determining the friction instability. The incorporation of friction surface inhomogeneity is, therefore, crucial and has to be counted to improve the accuracy of the numerical calculation to simulate brake noise. In this study, the heterogeneous nature of the friction material surface was employed in the simulation to improve the correlation between numerical simulations and experimental results. The distributions of contact stiffness and roughness on the friction material surface were used to represent the surface inhomogeneity in the complex eigenvalue analysis (CEA). The results from the noise simulation with uneven surface contacts minimized the difference between experiments and simulations and shed light on the possible improvement of the noise prediction from the CEA based simulations.