Crack paths under mixed mode (I+III) or (I+II+III) loadings

Fracture and fatigue experiments we have performed under mixed mode (I + III) and (I + II + III) loadings have shown that as the crack extends, the front gradually twists around the direction of propagation to reach a pure opening mode. This implies that the kink angle of the crack extension at the beginning of the propagation is variable along the front. The aim of this paper is to determine, in the context of linear elastic fracture mechanics, the value of this kink angle along the whole front. The values obtained are compared to the experimental ones. (C) Academie des Sciences/Elsevier, Paris.