Screw dislocation in a thin film–substrate in couple stress elasticity

We consider the interaction of a screw dislocation with a thin film–substrate interface in the anti-plane deformations of a couple stress elastic solid. We formulate and solve the corresponding boundary value problem in three main cases: when the screw dislocation is located inside the substrate; when the screw dislocation is located inside the film; and when the screw dislocation is located inside an unconfined (isolated) thin film in the absence of the substrate. In each case, we discuss the contribution of couple stresses to the interaction force acting on the dislocation. Moreover, we examine the changes in the interaction force resulting from the mismatch caused by the corresponding couple stress parameters.