Slip and Wear at a Corner with Coulomb Friction and an Interfacial Strength

Traditional analyses of slip at corners of contacts, based on linear elasticity and a Coulomb friction law, are very sensitive to the details of local geometries, owing to the effects of elastic singularities. Following the use of cohesive-zone models to address such issues in mode-II fracture, we present analyses of slip and wear at corners of contacts when a finite interfacial shear strength is incorporated with a Coulomb friction law. We show that the concept of an instantaneous cohesive-length scale, borrowed from the field of fracture mechanics, can be used to describe the nature of stress fields around corners, and defines when linear-elasticity and Coulomb friction can provide an accurate description of the interfacial behavior. We also show that the sensitivity of slip analyses to geometrical details decreases when the cohesive-length scale increases. We also show that the cohesive strength of an interface plays a crucial role in the propagation of a wear scar across an interface. If only Coulomb slip is assumed to occur, a wear scar may not progress beyond the original stick-slip boundary. If a finite interfacial shear strength is introduced into the analysis, the wear scar can propagate along the interface.