An internal variable approach to elastic-plastic fracture mechanics

An internal variable approach to the modelling of a cracked element is suggested. As well as providing an alternative failure criterion, the internal variable formulation treats elastic-plastic (or ductile) fracture as a structural problem, allowing the distinction to be made between fixed displacement and fixed loading conditions. Crack growth in a cracked elastic-plastic plate is determined for a particular form of the limit surface, and a simple criterion for stability emerges.