Crack Kinking from an Initially Closed Interface Crack in the Presence of Friction

Abstract

One studies crack kinking from an interface crack when this crack is closed prior to kinking but open after it. This problem was considered very recently by the authors with the considerably simplifying, but rather unrealistic hypothesis of absence of friction between the crack lips. Their work is extended here to account for possible friction obeying Coulomb’s law. One establishes the relation between the stress intensity factors just before and just after the kink. From there, using Goldstein and Salganik’s famous principle of local symmetry, one derives a theoretical value for the kink angle. This value depends upon both the mismatch of elastic properties between the materials and the friction coefficient. However, its range of variation is found to be quite narrow.