Dynamic Interaction Between Dislocation and Mode-III Crack

Abstract

The transient elastodynamic stress intensity factors of a sub-surface semi-infinite crack in an elastic half plane are analyzed. The crack is subjected to an incident SH wave initially, and some time later a screw dislocation emitting from a point located away from the crack tip. The crucial steps in the analysis are the direct application of integral transforms together with the Wiener-Hopf technique. Exact expressions are obtained for the resulting mode-Ill stress intensity factors as functions of time. The solution is constructed as a series. Each term in the solution series can be interpreted as the contribution of waves that have reflected at the free surface of half-plane different times. The first two terms in the series for the stress intensity factor history are then computed. The results are exact for the time interval from initial loading until the first wave scattered at the crack tip is reflected twice at the free surface of the half-plane and returns to the crack tip. Numerical results show that the smaller the emitting angle (and/or the smaller the emitting speed) of the dislocation is, the larger shielding effect to the crack.