A general phase-field model for simulating impact-sliding contact failure

Multiple failure modes of cyclic impact-sliding contacts, including brittle fracture, shear failure, and low-cycle fatigue, are investigated within the work. For this regard, a general thermo-elasto-plastic phase-field model is developed and validated that considers brittle-ductile failure mode transitions and fatigue degradation effects. And a temperature-dependent cyclic constitutive relation, combined with thermal softening, damage degradation, strain hardening, and fatigue degradation, is introduced to explain the cyclic thermo-elasto-plastic behavior of bearing steels. Combining the dynamic point/line contact model and the general phase-field model, the damage evolution and failure mode transitions of typical bearing parts under impact-sliding contacts are studied. The results indicate that cage-pockets and balls undergo low-cycle fatigue at low impact-sliding velocities, while guiding surfaces of the cage and ring are subjected to shear failure during cyclic high-speed sliding. Moreover, it is revealed that the abnormal phenomenon of more severe damage for the harder material than the softer material is due to multiple effects of strong thermal softening, damage degradation, and fatigue degradation.