A Zener-Stroh crack near an interface

A micro crack can be initiated by coalescing dislocations piled up along a slip plane. This mechanism was firstly proposed by Zener and later on analyzed by Stroh. The micro crack is thus called Zener-Stroh crack, which is a counterpart of the well-known Griffith crack in linear elastic fracture mechanics. In the present paper, we consider a Zener-Stroh crack initiated near a bi-material interface. Due to image force acted on the dislocations, a Griffith crack mechanism is introduced even where the crack is purely loaded by net dislocations. It is seen that the stress intensity factor, which consists of a Zener-Stroh component and a Griffith component, and the critical crack length are strongly affected by the presence of the interface. (C) 1997 Elsevier Science Ltd.