Abstract
The elastic interaction between a screw dislocation and a welded surface crack in a thin plate of composite material has been analysed using the conformal mapping technique. The effect of size on fracture is pronounced when the ratio of thickness to crack length is less than 10. However, when it exceeds 10, the problem can be simply treated as that of a semi-infinite composite material. Whether dislocation emission occurs at the tip also depends on the size of the specimen and the shear modulus ratio. The dislocation can be emitted more easily from the crack tip into the soft phase than into the hard one. The emitted angle of dislocation for minimal critical stress intensity factor increases with the shear modulus ratio. In addition, the results can be applied to several special cases. Finally, when the boundary value is not zero, such as in an applied stress, the mapping function must be selected carefully. © 1989.