Configurational force based analysis of creep crack growth

Abstract

Based on the concept of configurational forces, the driving force of cracks in elastic–plastic, creeping materials is derived. In a numerical study, the variation of the crack driving force with increasing creep time is compared to the behaviors of different parameters that have been used in literature to describe the tendency to creep crack growth. This is performed for the assumption of stationary cracks in C(T)-specimens made of Waspaloy at 700 °C. The loading conditions are varied so that small-scale creep, transition creep, or extensive creep conditions prevail. Either the load or the load-point displacement are held constant. It is demonstrated that, for the considered cases, the conventional creep crack growth parameters do not reflect the crack driving force, but qualitatively follow a behavior similar to the (absolute value of the) time derivative of the crack driving force.