A generalized strain energy density criterion for mixed mode fracture analysis in brittle and quasi-brittle materials

In this paper, a modified mixed mode fracture model called the generalized strain energy density criterion is proposed. The criterion uses three key crack parameters including: the mode I and mode II stress intensity factors ( KI and KII) and the T-stress for predicating the mixed mode fracture resistance in brittle and quasi-brittle materials. The main purpose of this paper is to show that the T-stress has a major role in mixed mode I/II brittle fracture when an energy-based criterion is employed. The theoretical results obtained from the generalized strain energy density criterion are compared with the experimental results reported in previous papers for semi-circular bend specimens made of PMMA and Harsin marble and also for cracked triangular specimens made of Neiriz marble. It is shown that the results predicted using the modified criterion are in significantly better agreement with the experimental results compared with the conventional minimum strain energy density criterion.