On the accuracy of ductile fracture assessment of through-wall cracked pipes

Ductile fracture assessments of circumferentially through-wall cracked piping components performed on the basis of the elastic–plastic J -integral concepts are discussed with particular interest in its ability and accuracy to predict actual experimental loads corresponding to initiation of stable crack growth and failure stages. Possible source of uncertainty in the modeling of material behaviour is treated separately, comparing results with each other and with experimental data. Especially J estimation schemes for evaluating applied J -integral are checked against 3D non-linear finite element analysis (FEM) using the advanced fracture analysis code WARP3D. The influence of stress–strain curve used as an input to the FEM analysis on the predicted results of crack initiation and maximum loads is examined in circumferentially through-wall cracked pipes. The elastic–plastic fracture mechanics based J -integral combined with J – T analysis is found to give an accurate and complete description of component behaviour. An approximation of material stress–strain curve is given based on the interpretation of experimental results.