Numerical simulation of fatigue plasticity-induced crack closure for through cracks with curved fronts

• 3D simulation of plasticity induced crack closure throughout fatigue propagation.
• Influence of the history of crack front curvature throughout fatigue propagation.
• Local effective stress intensity factor as a driving force.
• Explanation of the experimentally observed crack shape.

The plasticity-induced crack closure of through-thickness cracks, in CT specimens of 304L austenitic stainless steel, is numerically simulated using finite elements. Crack propagation is achieved through node releasing, by applying constant ΔK amplitude, so as to limit the loading history influence. The calculation of the effective stress intensity factor range, ΔKeff, along different shapes of crack fronts close to real crack fronts, are compared to calculation previously performed for through-thickness straight cracks. The results for the curved crack fronts support that ΔKeff is the driving force of the propagating crack.