Shielding effect and emission criterion of a screw dislocation near an interfacial blunt crack

Shielding effect and emission criterion of a screw dislocation nearan interfacial blunt crack are dealt with in this paper. Utilizingthe conformal mapping technique, the closed-form solutions arederived for complex potentials and stress fields due to a screwdislocation located near the interfacial blunt crack. The stressintensity factor on the crack tips and the critical stress intensityfactor for dislocation emission are also calculated. The influenceof the orientation of the dislocation and the morphology of theblunt crack as well as the material elastic dissimilarity on theshielding effect and the emission criterion is discussed in detail.The results show that positive screw dislocations can reduce thestress intensity factor of the interfacial blunt crack tip(shielding effect). The shielding effect increases with the increaseof the shear modulus of the lower half-plane, but it decreases withthe increase of the dislocation azimuth angle. The critical loads atinfinity for dislocation emission increases with the increase ofemission angle and curvature radius of blunt crack tip, and the mostprobable angle for screw dislocation emission is zero. The presentsolutions contain previous results as special cases.