3D-generalized maximum tangential strain criterion for predicting mixed-mode I/II/III fracture initiation of brittle materials considering T-stress effects

To overcome the difficulty of predicting the initiation and conditions of three-dimensional (3D) cracks, we proposed a novel 3D-generalized maximum tangential strain (3D-GMTSN) criterion for mixed-mode I/II/III loading conditions, considering the effects of T-stress and Poisson’s ratio. The proposed strain-based criterion can predict the initiation direction and conditions of cracks under mixed-modes I/II, I/III, II/III, and I/II/III. The criterion was compared with the existing criteria for mixed-modes, and the results were compared with the experimental results. Our study indicated that the criterion considering T-stress effects can predict the crack initiation angles and the critical stress intensity factors (CSIFs) for arbitrary mixed-mode fractures. Specifically, the criterion provides better predictions of the CSIFs under the mode II-dominant conditions. The 3D-GMTSN criterion was better for predicting the out-of-plane crack initiation angles and CSIFs of brittle materials containing mode III cracks as compared to the existing criteria.