The Size of a Uniform Stress Process Zone at Fracture Initiation

Abstract

The process zone description is often used to represent the micro-mechanistic processes that are operative in the immediate vicinity of a crack tip. The process zone is an infinitesimally thin strip, and the theoretical analysis is considerably simplified if the stress within the process zone is assumed to be uniform. The paper derives an expression for the size of a uniform stress process zone when fracture initiates at the tip of a sharp crack. The expression relates this size to the size appropriate to the case of a semi-infinite crack in an infinite solid, and is a two term expression in terms of the ratio of this size to a characteristic structural dimension. The expression is validated against known results for specific geometrical configurations.