Elasto-Plastic Rough Surface Contact Analysis for the Effects of Material Properties, Topographical Characteristics and Load

Interaction of nominally flat engineering surfaces that lead to a large apparent contact area exists in many mechanical systems. Such an interaction can be modeled based on the periodic similarity of the surface topography and a numerical three dimensional elasto-plastic contact model [1] with the assistance of the continuous convolution and Fourier transform (CC-FT) algorithm. In this model, frequency response functions (FRF) are built to link the pressure excitation with the deformation response of materials. This model takes into account asperity interactions and work hardening caused by plastic strain. Contact pressure, real contact area, surface clearance, and resultant subsurface plastic strain and stress fields can be calculated. Following the two-dimensional digital filter technique developed by Hu and Tonder [2], rough surfaces can be generated numerically with specified autocorrelation length ratio λ *=β y /β x RMS roughness R q , skewness Sk, and kurtosis K (Fig. 1). A group of contact simulations has been performed for surfaces with various statistical characteristics, material properties, and loads. The behaviors of nominally flat contact, such as the contact area ratio, Λ=A c /A n , the average gap, $$ \Gamma = \bar h/R_q $$ and the volume containing plastic deformation, Ω=V p /A n R q , are obtained as functions of the average contact pressure (Fig. 2). The effects of topographic, material, and strain hardening parameters on the contact behaviors of rough surfaces are discussed in detail in this paper. Figure 1 A rough surface generated by computer Figure 2 Contact behaviors versus average pressure