The effect of superdislocation on fracture: Dislocation-free zone in the front of a semi-infinite crack tip

Abstract

The effect of superdislocation on mode II or mode III fracture has been investigated. The plastic zone between a semi-infinite crack tip and a superdislocation with a dislocation-free zone is simulated by a continuous dislocation distribution. The dislocation distribution functions in the crack and plastic zone are analytically derived. A close form of the number of dislocations in the plastic zone and stress field along the x axis are obtained. From the stress field, the stress intensity factor KIII at the crack tip and stress concentration at the superdislocation are available. When the distance between crack tip and superdislocation is larger than the plastic zone size, the stress intensity factor is proportional to the square root of plastic zone size KIII, but is inversely proportional to the distance between crack tip and superdislocation. On the other hand, when the distance between crack tip and superdislocation is almost the same as the plastic zone size, the stress intensity factor is inversely proportional to the square root of distance between crack tip and superdislocation. It is also found that the applied stress is determined by the superdislocation. Finally, our results can be reduced to several special cases.