Three-dimensional mixed-mode (I and II) crack-front fields in ductile thin plates - effects of T-stress

It has been well-established that the non-singular T-stress provides a first-order estimate of geometry and loading mode (e.g. tension versus bending) effects on elastic-plastic crack-front field under mode I loading conditions. The objective of this paper is to exam the T-stress effect on three-dimensional (3D) crack-front fields under mixed-mode (modes I and II) loading. To this end, detailed 3D small strain, elastic-plastic simulations are carried out using a 3D boundary layer (small-scale yielding) formulation. Characteristics of near crack-front fields are investigated for a wide range of T-stresses (T/sigma(0) = - 0.8, - 0.4, 0.0, 0.4, 0.8). The plastic zones and thickness and angular and radial variations of the stresses are studied, corresponding to two values of the remote elasticmixity parameters M-e = 0.3 and 0.7, under both low and high levels of applied loads. It is found that different T-stresses have a significant effect on the plastic zones size and shapes, regardless of the mode mixity and load level. The thickness, angular and radial distributions of stresses are also affected markedly by T-stress. It is important to include these effects when investigating the mixed-mode ductile fracture failure process in thin-walled structural components.