Mechanical and Thermomechanical Elastic-Plastic Contact Analysis of Layered Media With Patterned Surfaces

An elastic-plastic finite element analysis of a sphere in normal and sliding contact with a layered medium possessing a patterned surface with regularly spaced rectangular pads was conducted in order to investigate the effect of pattern geometry on the contact pressure distribution and subsurface stress-strain field. Three-dimensional sliding simulations were performed for lateral displacement of the indenting sphere approximately equal to two times the pad spatial periodicity. Three complete loading cycles, involving indentation, sliding, and unloading of a rigid sphere, were simulated to assess the effect of repeated sliding on the stresses in the first (hard) layer and plastic deformation in the underlying (soft) layer. Thermomechanical sliding contact simulations of an elastic-plastic layered medium with a patterned surface and an elastic-plastic sphere with properties identical to those of the first layer were carried out to examine the effect of frictional heating on the deformation behavior of the medium. Results are presented for the temperature distribution and maximum temperature variation at the surface and the evolution of subsurface plasticity in terms of Peclet number. The likelihood of thermal cracking in the wake of microcontacts during sliding is interpreted in the context of the thermal tensile stress due to the temperature gradients in the layered medium.