Numerical analysis of plasticity effects on fatigue growth of a short crack in a bainitic high strength bearing steel

• The crack was open to the tip throughout the simulated growth distance.
• The crack tip load was limited by a compressive residual stress at the crack tip.
• Build-up of negative residual stresses explained the short crack growth transition.
• LEFM and ΔKeff described the crack tip load for the physically short crack.
• The pressure sensitive yield surface was needed for finding the rate limiting SIF.

Plasticity effects on fatigue growth were simulated for a physically short crack. The material description comprised the Drucker-Prager yield surface, non-associated flow rule and non-linear combined hardening. The simulated development of the growth limiting parameter agreed with the experimental crack behaviour with early rapid propagation followed by a transition to slow R-controlled growth. The crack was open to the tip without any crack face closure throughout all load cycles. Instead compressive residual stresses developed at the unloaded tip which supplied an explanation to the slow rate of the propagated short crack in this bainitic high strength bearing steel. The material’s strength differential effect was the key difference explaining why compressive residual stresses instead of crack face closure was responsible for the short crack effect in this material.