Rolling contact fatigue crack propagation on contact surface and subsurface in mixed mode I+II+III fracture

Abstract

Rolling contact fatigue (RCF) is the critical damage from rolling bearings constraining the service, performance, and reliability, which is directly caused by fatigue crack propagation. The crack paths on both the contact surface and subsurface were observed after the bearing fatigue test. The three-dimensional geometry of the RCF crack was characterized and reconstructed based on experimental statistics. Finite element analysis was performed to obtain the mixed mode stress intensity factors (SIFs) along the crack fronts, and the crack propagation behavior was numerically studied. Results indicated that the propagation of cracks on the contact surface and subsurface causes the gradual formation of micropits and the sudden spalling of material respectively. Initial micro-cracks with an inclination angle of 15–30° have the highest growth rate, which should be prevented during the bearing raceway manufacturing process. The propagation paths of the RCF cracks can be more accurately predicted by considering the superposition of fracture mode I + II + III in three-dimensional, and mechanisms of crack propagation on contact surface and subsurface were revealed respectively.