A screw dislocation near to a sub-surface crack, which was parallel to both free surfaces of a thin plate, was investigated. On the basis of the Schwarz-Christoffel transformation, the system was mapped into that of a screw dislocation near to a free surface. The stress field, stress intensity factor, image force and strain energy were derived. The stress contours were plotted in order to demonstrate the validity of the solution. The effect was studied of the layer thickness, between the crack surface and the second free surface, upon the stress intensity factor, image force and strain energy for a given distance between the first free surface and the crack surface. The solution could be reduced to the case of a screw dislocation near to a sub-surface crack in a semi-infinite medium.

Screw Dislocations Near to a Sub-Surface Crack in a Thin Plate. S.D.Wang, S.Lee: Materials Science and Engineering A, 1998, 246, 61-8