Investigation on characteristic of J integral parameter in welded joints

The J integral parameter and its application feasibility in welded joints with different weldmatchings in yield strength (overmatching weld and undermatching weld), different material constitutive laws (material with a Ludes yield plateau and power hardening) and under different fracture types (ligament yielding fracture and general yielding fracture) are investigated. First the condition of J integral path independent has been studied based upon finite element analysis by using ADINA procedure on welded joints. It was shown that the J integral is path dependent for the cases studied in this paper. Then experiments were carried out to study availability of J integral as a plastic singularity parameter at the tip of the notch in welded joints. The results show that J dominance in most cases studied is not validated in v and u displacement fields. From both considerations mentioned above it can be concluded that J-integral as controlling parameter used to estimate the safety of welded structures is not always made clear.