Effect of dislocation dipoles on fracture behavior in two-phase medium

On the basis of the results of Lin et al. [Mater. Sci. Eng., 95, 167 (1987)], we have investigated the elastic interaction between screw dislocation dipoles and an internal crack in a two-phase medium. The complex potential, stress field, stress intensity factor, crack extension force, strain energy, image force and image torque are derived. The magnitude of each physical variable in the dipole system is smaller than those of the counterparts in a monopole system. Both the translation and rotation must be considered in the static equilibrium. The mechanical behavior of the medium is strongly influenced by the shear modulus ratio of the two-phase medium and the dislocations inside the internal crack. Finally, our results can be reduced to several special cases.