Transient dislocation emission from a crack tip under dynamic mode-III loading was analyzed. By taking account of dynamic interactions between cracks and dislocations, the governing equation for dislocation motion was derived for quasi-stationary conditions. The dislocation emission behavior was analyzed by solving this equation numerically. A critical initial speed could be identified which had to be exceeded by the dislocations in order to escape from the crack tip. The dislocation emission process was found to be completed in such a short time that the applied load could be treated as being approximately constant during dislocation emission. On this basis, an asymptotic criterion for transient dislocation emission was developed from which the critical initial speed could be evaluated. In the case where the dislocation was emitted from rest, the quasi-static criterion for dislocation emission was recovered.

Transient Dislocation Emission from a Crack Tip under Dynamic Mode III Loading. Y.S.Wang, D.Gross, G.Y.Huang: Archive of Applied Mechanics, 2001, 71[8], 567-8