Elastic interaction between screw dislocations and a blunting interfacial crack

Using the conformal mapping technique, the elastic interaction between a screw dislocation and an interfacial crack emanating from a semielliptic hole is investigated. We have derived the complex potential, the stress field, the strain energy, the force on the dislocation, the stress intensity factor at the crack tip, the critical stress intensity factor K_D for dislocation emission and the critical stress intensity factor K_c for brittle fracture. From the image force, we find that there are zero-force points near the surface of the semielliptic hole if the applied stress is sufficiently large. The ductile vs. brittle behaviour of two-phase material can be determined by the relative magnitudes of _D and K_c. A two-phase material with a larger shear modulus ratio and sharp crack will be more brittle. Finally, our results can be reduced to several special cases.