Criterion for initiation of cracks under mixed-mode I plus III loading

The initiation of crack growth under a combination of opening and anti-plane shearing mode loading is considered in this paper. It is shown that such cracks do not grow through a continuous evolution of the crack surface. Rather, an abrupt fragmentation or segmentation of the crack front is generated. Through experimental observations and a theoretical model, we postulate a relationship between the scale of the fragmentation and the mode mix.