Strain factor ratio criterion for crack extension in anisotropic plates

Due to the fact that certain brittle extensions of cracks in anisotropic ma terials are caused by the surpassing of the limit strain by the actual stra in produced by the load, a strain criterion (r(e)-criterion) is proposed in this paper. Parameter studies of the r(e)-criterion for the extension dire ction and initiating load are carried out. Comparisons between the r(e)-cri terion, some stress criteria, and the independent experimental results are made. It is shown that the r(e)-criterion can predict quite accurately both the extension direction and the initiating load. The r(e)-criterion is mor e general than the stress factor ratio criterion in that it takes into acco unt the influence of Poisson's ratio in predicting the crack extension dire ction and the initiating load. The r(e)-criterion can be reduced to the str ess factor ratio criterion in certain cases. The prediction of crack extens ion direction and initiating load can be quite different using different cr iteria.