The elastic interactions of a dislocation and a crack were compared for four bonding conditions of the crack plane. Four cases (monocrystalline material, sliding grain boundary, perfectly bonded interface, sliding interface) were considered. The stress intensity factors which arose from edge and screw dislocations, and their image forces, were studied for the above four cases. The stress intensity factor at a crack tip along the perfectly bonded interface, which arose from a screw dislocation, could be deduced from that in monocrystalline material if the shear modulus in the monocrystalline material was replaced by the harmonic mean of both shear moduli in the bi-material. The stress intensity factor at a crack tip along the sliding interface, which arose from an edge dislocation in the bi-material, could be obtained from that along the sliding grain boundary in the single material if μ/(1 - υ) for the latter was replaced by the harmonic mean of the μ/(1 - υ) values for the bi-material. The solutions for a screw dislocation near to a crack along a sliding grain boundary and a sliding interface were the same as that for a screw dislocation and its mirror image. In general, the effect of an edge dislocation on a perfectly bonded interface, with respect to crack propagation, was more pronounced than that for a sliding interface. The effect of an edge dislocation upon crack propagation was of mixed-mode for the cases of a perfectly bonded interface and a monocrystalline material, but involved mode-I fracture for the cases of a sliding interface and a sliding grain boundary. All of the curves of force, versus distance between the dislocation at the interface and the right-hand crack tip, were similar; regardless of the dislocation source for both a sliding interface and a perfectly bonded interface.

Comparison of Elastic Interaction of a Dislocation and a Crack for Four Bonding Conditions of the Crack Plane. B.T.Chen, C.T.Hu, S.Lee: International Journal of Fracture, 1998, 91, 149-64