Dynamic mode I and mode II crack kinking including delay time effects (Q1089195)

The dynamic stress intensity factor of an initially stationary semi- infinite crack in an unbounded linear elastic solid which kinks at some time \(t_ f\) after the arrival of a stress wave is obtained as a function of crack tip velocity \(v_ c\), kink angle \(\delta\), time t and the delay time \(t_ f\). A perturbation method, using the kinking angle \(\delta\) as the perturbation parameter, is used. The solutions can be compared with numerical results and other approximate results for the case of \(t_ f=0\) and give excellent agreement for a large range of kinking angles. The results indicate that if a maximum energy release rate is accepted as a crack propagation criterion, then for both the incident stress wave parallel to the original crack faces and uniform dynamic loading applied to the original crack faces, the crack will propagate straight ahead of the original crack for any delay time.