Creep-fracture resistance parameters determination based on stress and ductility damage models

摘要

The stress, strain rate, and process zone with respect to the creep-crack growth in pure modes I and II are analysed by using damage-evolution equations. The damage models for the fracture of the process zone are represented using a stress- and ductility-based formulation. According to the stress-based model, 2 expressions are proposed to describe the stress-sensitive nature of a multiaxial rupture behaviour. Following the ductility model, new multiaxial failure strain conditions are derived. Both damage-free and defective creeping solids have been studied. The variations in the creep stress or strain and crack-tip governing parameter in terms of the creep I_n-integral with respect to time and the evolution of creep damage are analysed using a finite element model. The effect of the introduced creep stress intensity factor as a function of the creep time, loading biaxiality, and creep damage models is discussed in detail.