Boundary Element Analysis of Effects of Crack Face Friction and Trapped Fluid on Rolling Contact Fatigue Cracks

Abstract

Boundary element analysis has been performed on the cycle of stress intensity factors at a surface initiated rolling contact fatigue crack tip under a Hertzian contact pressure distribution. The model includes the effects of Coulomb friction between the faces of the crack and the possible effect of fluid penetrating into the crack. Three possible models to show the influence of fluid on crack propagation have been investigated, namely, (a) a fluid lubrication model; (b) a hydraulic pressure model; and (c) a fluid entrapment model. The analysis results indicate that when the fluid entrapment model was used, the values of generated mode I and II stress intensities were reasonable and the results were consistent with the behavior of the crack. Therefore, the fluid entrapment model is considered to be the most promising for explaining the behavior of the rolling contact fatigue cracks.