Effects of surface defects on rolling contact fatigue of heavily loaded lubricated contacts

Surface-initiated fatigue caused by surface defects is one of the most dominant failure modes for bearing contacts. In this study, a damage mechanics-based Voronoi finite-element model (VFEM) is developed and used to investigate the effects of surface defects (such as dents and fretting wear) in elastohydrodynamic lubricated line contacts. A line contact elastohydrodynamic lubricated model is used to calculate the pressure distributions acting over the surface defects, which are then employed by Voronoi finite-element model to determine subsurface stresses. Continuum damage mechanics-based approach is used to incorporate cyclic damage accumulation and progressive degradation of material properties with rolling contact cycling. The model also takes into account the effects of residual stresses generated during the debris denting process. Using this methodology, the model is used to simulate microcrack initiation, coalescence, and propagation stages, finally a fatigue spall. The locations and patterns of dent-initiated spalls are found to be consistent with experimental observations. The fatigue model is used to study the effects of the topology of the material microstructure, dent sharpness, and material properties on rolling contact fatigue (RCF) life and Weibull slopes.