Discrete dislocation plasticity models and strain-gradient plasticity theories were used to investigate the role of interfaces in the elastic–plastic response of a sheared single crystal. The upper and lower faces of a single crystal were bonded to rigid adherents via interfaces of finite thickness. The sandwich system was subjected to simple shear, and the effect of thickness of crystal layer and of interfaces upon the overall response were explored. When the interface has a modulus less than that of the bulk material, both the predicted plastic size effect and the Bauschinger effect were considerably reduced. This was due to the relaxation of the dislocation stress field by the relatively compliant surface layer. On the other hand, when the interface has a modulus equal to that of the bulk material a strong size effect in hardening as well as a significant reverse plasticity were observed in small specimens. These effects were attributed to the energy stored in the elastic fields of the geometrically necessary dislocations.

Compliant Interfaces: a Mechanism for Relaxation of Dislocation Pile-Ups in a Sheared Single Crystal. K.Danas, V.S.Deshpande, N.A.Fleck: International Journal of Plasticity, 2010, 26[12], 1792-805