Roughness- and plasticity-induced fatigue crack closure under single overloads: Finite element modelling

Results from finite element modelling of plasticity-induced crack closure (PICC) and roughness-induced crack closure (RICC) of fatigue cracks subjected to single overloads are presented. Effects of L/rp ratios on RICC, where L and rp represent crack asperity length and plastic zone size, respectively, are seen to be functionally similar to results presented previously for constant amplitude fatigue loading [Kamp N, Parry MR, Singh KD, Sinclair I. Acta Mater 2004;52:343–53], particularly in the saturation of the influence of RICC for L/rp(OL) ⩾ 1, where rp(OL) is the overload plastic zone size. The present work is seen to map out overload regimes where RICC and PICC effects may be expected to influence crack growth transients. Comparisons of modelled and experimental closure levels, and growth rate studies are presented, with the accompanying paper [Singh KD, Khor KH, Sinclair I. Acta Mater (in press)] considering a simplified analytical representation of the effects presented here.