Models of Potential and Wear Particles in a Spherical Contact

The main goal of the current study is a numerical prediction of adhesive wear volume in a spherical contact. The contact consists of a deformable sphere and a rigid flat subjected to combined normal and tangential loading under full stick contact condition. Following the completion of the normal loading a tangential load is applied gradually leading to a decrease in the stiffness of the contact and eventually to sliding inception. Due to the full stick contact condition the sliding inception can occur on a certain surface beneath the contact interface. The entire volume contained between this incipient sliding surface and the contact interface defines a potential wear particle. Further increase of the tangential loading will eventually result in a detachment of a certain actual wear particle from the sphere. The detachment surface, which differs from the incipient sliding surface, occurs where the sphere material has failed due to reaching the ultimate shear or tensile strain. The volume contained between this detachment surface and the contact interface forms the actual wear particle that adheres to the moving flat and results in material transfer. Empirical expressions for the volumes of the potential and actual wear particles are developed showing their dependency on material properties and the normal preload.