Fracture and fatigue of the surface layer of layered media due to adhesive sliding contact

Abstract

Layer cracking in a layered medium consisting of an elastic-perfectly plastic half-space (substrate) and a relatively stiff, elastic surface layer in adhesive sliding contact with a rigid asperity was analyzed with the finite element method using linear elastic fracture mechanics. The directions of tensile and shear mode fracture were determined from the maximum tensile and shear stress intensity factors (SIFs), respectively, whereas the directions of tensile and shear mode fatigue crack growth were determined from the maximum range of tensile and shear SIFs, respectively. The effects of asperity position, interfacial adhesion (Maugis parameter), crack depth, asperity interaction distance, layer thickness, and material properties of the elastic layer and the elastic-plastic substrate on fracture and fatigue crack growth in the layer are interpreted in the context of simulation results. It is shown that the propensity for fracture and fatigue in the layer is enhanced with increasing asperity interaction distance and Maugis parameter and decreasing crack depth and layer thickness. The numerical results of this study reveal that, for similar tensile and shear fracture toughness, layer fracture in adhesive sliding contact predominantly occurs by the out-of-plane tensile mode of fracture, whereas fatigue crack growth in the layer is a manifestation of the in-plane shear and out-of-plane tensile modes of fatigue crack growth.