Abstract
A screw dislocation near a subsurface crack parallel to both free surfaces in a thin plate was investigated. Based on the Schwarz-Christoffel transformation, the system was mapped to that of a screw dislocation near a free surface. The stress field, stress intensity factor, image force and strain energy were derived. The stress contours were plotted to show the validity of the solution. For a given distance between the first free surface and crack surface, the effect of layer thickness between the crack surface and the second free surface on stress intensity factor, image force and strain energy was studied. This solution can be reduced to the case of a screw dislocation near a subsurface crack in a semi-infinite medium.