Driving force on line fracture process zone and fracture parameters suitable for elastic–plastic materials

Abstract

The driving force on the line, zero height, fracture process zone (FPZ) is investigated in this paper. First, basic laws for crack propagation based on the configurational force approach are derived in the framework of traditional continuum mechanics. The driving force on steady line FPZ is a direct consequence of these derivations. Fracture parameters suitable for growing cracks in elastic–plastic materials such as near tip integrals based on the incremental theory of plasticity, the energy-, displacement-, and strain-type parameters are consistent with the driving force on steady line FPZ. Therefore, the steady line FPZ has provided a unified framework encompassing the fracture parameters of stable crack growth in elastic–plastic bodies. Besides, the driving force on non-steady line FPZ is also derived, which consists of the driving force related to the self-expansion of FPZ and the driving force corresponding to the translation of FPZ. Before the crack initiation, the work of separation in the cohesive zone model (CZM) is associated with the self-expansion driving force. During the steady-state crack growth, the work of separation is equal to the translation driving force. Since the translation driving force is independent of the self-expansion driving force, the cohesive parameters at the crack initiation can differ from those during the steady-state phase.