DAMAGE WORK AS DUCTILE FRACTURE CRITERION

This paper treats the ductile failure initiation in circumferentially- notched tension specimens and explores the local damage model that is able to represent the continuous degradation of the deforming material . With the aid of finite element calculations, the notched specimens h ave been simulated numerically and the whole strain-stress history for each geometry derived. This allows determination of the evolution of strain-stress fields until fracture occurs. Two damage models were eva luated: the Rice and Tracey cavity growth model and a model which comb ines the latter with the plastic strain work, to derive an intrinsic p arameter called 'damage work'. These models could predict the location where the crack will initiate as well as the crack initiation step wh ich is reached for a relatively constant value of the critical damage.