Effect of Surface Patterning on Contact Deformation of Elastic-Plastic Layered Media

A plane-strain finite element analysis for patterned elastic-plastic layered media was performed in order to elucidate the effect of surface geometry on the deformation and stress fields due to normal and sliding contact. Surface interaction between the layered media and a rigid asperity was modeled with special contact elements. Results for the contact pressure distribution, surface tensile stress, and subsurface equivalent plastic strain are presented for layered media with different meandered and sinusoidal surfaces. The significance of surface patterning on the deformation behavior is interpreted in terms of stress and strain results illustrative of the tendency for crack initiation and plastic deformation in the first two layers, where deformation is confined in all simulation cases. Relations for the contact pressure concentration factor and onset of yielding in the first (hard) layer are derived from finite element results for indented layered media with sinusoidal surface patterns. Predictions for the indentation depth at the onset of yielding based on the developed yield criterion are shown to be in good agreement with those obtained from finite element simulations.