The effect of constraint on creep fracture assessments

This paper describes a preliminary examination of the effect of in plane co nstraint on creep crack growth under widespread creep conditions using the Q stress. Plane strain is assumed. Damage models for fracture of the proces s zone based on both ductility exhaustion and stress rupture are shown to p redict a variation of the crack growth rate with Q. Lower levels of constra int lead to lower crack growth rates for a given C*. The results are used t o outline a high temperature failure assessment diagram approach to constra int dependent creep crack growth.