Abstract
Using the conformal mapping technique, the interaction between a screw dislocation and a welded surface crack in a bimaterial has been analysed. The complex potential, stress field, stress intensity factor, crack extension force, strain energy and image force on the dislocation are obtained. In the absence of an applied stress, the interfacial properties can be obtained simply by replacing the shear modulus of a single-phase medium by the effective shear modulus, which is the harmonic mean of the shear moduli of the two phases. Under the action of an applied stress, one metastable point appears in hard phase, however, the number of metastable points existing in soft phase is dependent on the magnitude of the applied stress. It is different from that of a single-phase medium in which three metastable points are located on the crack coplanar surface and in two symmetric positions with mirror plane y = 0, respectively. In general, the role of dislocations around the crack tip in the fracture for two-phase medium is similar to that for single-phase medium except the difference in magnitudes. In addition, the results can be reduced to several special cases and some of them are in good agreement with those derived in previous reports. © 1989.