Application of a modified damage potential to predict ductile crack initiation in welded pipes

The mesh dependency of the cavity growth model due to Rice and Tracey has been overcome by integrating it over a process zone surrounding the crack tip. This integral represents a modified damage potential. The critical value of the integral for crack initiation in weld material has been determined from a welded CT specimen by comparing the computed J with the experimentally measured J-initiation value. This critical value is then employed in 8 and 12 in. welded pipes having different through-wall cracks at the centre to predict the crack initiation loads under four-point bending. Close agreement between the computed crack initiation loads and the experimentally measured values justifies the usefulness of the present modified damage potential.