Effect of surface topography on mode-coupling model of dry contact sliding systems

Dry contact sliding between two structures is frequently found to generate squeal noise in certain topography condition of contact surface. Furthermore, a different surface topography may generate squeal noise at different frequencies. In this paper, authors investigate the effect of topography of contact surfaces to the normal contact stiffness, the tangential contact stiffness, and the friction coefficient. The normal and tangential contact stiffness are determined by a classical model of asperity on contact surface. These parameters will be the dominant factors of the squeal noise generation by means of mode-coupling analysis. Numerical simulation-based investigation is carried out using two simple models, i.e. a two-degree of freedom model and a simple space frame model. The simulation results show that a structure has only one or few pairs of couple modes with complex eigenvalues at certain contact conditions. For a system with multi-degrees of freedom, some mode shapes make couples in different contact conditions. On the other hand, smoother contact surfaces have higher normal and tangential contact stiffness. Furthermore, higher tangential contact stiffness and higher coefficient of friction will increase the possibility of squeal generation. Hence, it is understandable why the squeal noise appears and vanishes in some surface topography and has different frequencies at different values of surface roughness.