A screw dislocation in a three-phase composite strip

Using the technique of analytic continuation, we derive analytical solutions to the problem of a screw dislocation in a three-phase strip. The two traction-free boundaries of the strip are perpendicular to the two perfect interfaces formed by adjacent materials. The screw dislocation can be located anywhere in the composite strip. Elementary expressions for the image force acting on the screw dislocation are obtained. When the strip is extremely thick, our solutions simply recover those in the literature. Our solutions allow us to observe some very interesting and quite unexpected phenomena concerning the mobility and stability of the screw dislocation interacting with the aforementioned interfaces and boundaries.