Conditions for J-dominance in three-dimensional thin cracked plates

Based on detailed full-field finite element analysis of a thin ductile plate, we have characterized the three-dimensional fields in the vicinity of a crack front and determined size requirements for existence of J-dominated fields under various load levels. In the analysis, the plate thickness is assumed to be sufficiently small so that it is the only physical length scale of the problem. When a plane stress small scale yielding condition exists at far field, strong 3D effects are observed within a radial distance of about one-half thickness from the crack front. We have also identified the stress field at points very close to the crack front and investigated the existence of local plane strain HRR fields. It appears that under small scale yielding conditions, the 2D plane stress HRR-field and a dominant local plane strain HRR-field along crack front can not coexist within a thin plate.