The mechanical crack tip opening displacement fracture criterion in piezoelectric ceramics

In order to interpret the two different kinds of experimental results of the effect of applied electric fields on the critical load at present, a new fracture criterion, the mechanical crack tip opening displacement (MCOD), is proposed in this paper. The fracture criterion predicts that the effect of applied electric fields on the critical load is different in two cases. The two theoretical results are all in according with the two kinds of experimental observations. It is interesting that the existing contrary experiments can be fully interpreted by the MCOD fracture criterion based on the results in this paper.