Localized plasticity near a crack tip in a strain hardening material subjected to mode I loading

In this paper, very detailed finite deformation analyses of a cracked elastoplastic panel with a straight crack subjected to mode I (opening) loading were performed for the case of a strain hardening elastic-plastic material. The most original modeling result was the presence of localized plasticity in the form of shear bands which appear even in the case of monotonic loading (i.e. not only for cyclic loading) if — and only-if — a material constitutive equation including kinematic hardening is used. Implications of this original result for fatigue and fracture mechanisms near the crack tip are discussed in the paper. Particular emphasis is given to the consequences of environmentally assisted cracking processes by localized anodic dissolution or hydrogen assisted cracking in which metal dissolution (with its associated crack tip blunting), and hydrogen transport by dislocation dragging or stress-strain assisted diffusion may be influenced by the presence of these localized shear bands in the vicinity of the crack tip.