Criterion of local symmetry visualized in small eccentric single edge notched bend (E-SENB) rock specimens

Fracture criterion of local symmetry has been widely used to predict the fracture kink and simulate the fracture trajectory in rocks under the mixed-mode loading. Under small scale yielding, it must include two aspects: the local mode I stress intensity factor (SIF) kI is maximum and the local mode II SIF kII is zero. When fracture just initiates, the local kII is not zero, but it will be gradually eliminated after the crack propagates....