The problem of a screw dislocation, located in an annular coating layer which was imperfectly bonded to an inner circular inhomogeneity and to an outer unbounded matrix, was first addressed in detail. Both the inhomogeneity–coating interface and coating–matrix interface were modelled by a linear spring with vanishing thickness to account for the possible damage occurring on the interface. An analytic solution in series form was derived by means of complex variable method, with all the unknown constants being determined explicitly. The solution was then applied to the study of the dislocation mobility and stability due to its interaction with the two imperfect interfaces. The most interesting finding was that when the middle coating layer was more compliant than both the inner inhomogeneity and the outer unbounded matrix and when the interface rigidity parameters for the two imperfect interfaces were greater than certain values, one stable and two unstable equilibrium positions could exist for the dislocation. Furthermore, under certain conditions an equilibrium position, which could be either stable or unstable (i.e., a saddle point), could exist, which had never been observed in previous studies. Results for a screw dislocation interacting with two parallel straight imperfect interfaces were also presented as the limiting case where the radius of the inner inhomogeneity approaches infinity while the thickness of the coating layer was fixed.

New Phenomena Concerning a Screw Dislocation Interacting with Two Imperfect Interfaces. X.Wang, E.Pan, A.K.Roy: Journal of the Mechanics and Physics of Solids, 2007, 55[12], 2717-34