Failure assessment of subsurface rolling contact fatigue in surface hardened components

A failure assessment diagram for components subjected to rolling contact with hardness varying along the depth is presented. The approach takes into account the influence of inherent defects on subsurface fatigue: considering a 2D plane strain model, crack propagation from inherent defects was assessed in terms of applied stress intensity factor; defect-free fatigue was assessed in terms of the Dang Van stress. By analysing different combinations of loading condition, defect dimension and hardness profile, it was possible to obtain a general relationship for subsurface rolling contact fatigue prediction. A good agreement was found between predicted contact pressure limit and some published experimental results.