An elastic-plastic stress analysis of a polymeric subsurface with a thin layer under normal and tangential loading

Abstract

A finite element method was employed to investigate stress and strain distributions in the subsurface of high density polyethylene (HDPE) by an elastic-plastic analysis. Various equivalent stress and strain contours in the subsurface area under the asperity contact were obtained for three kinds of HDPE, i.e. gamma-ray-irradiated HDPE, helium-plasma-treated HDPE, and untreated HDPE. It was assumed that the untreated HDPE has a soft surface layer over the bulk, the plasma-treated HDPE has a hard surface layer, and the gamma-irradiated HDPE has a homogeneous surface area owing to uniform cross-linking. Wear mechanisms of untreated and irradiated HDPE were explained qualitatively based on the plastic deformation and the strength of the material.