In this study, an estimation method is proposed to evaluate the energy release rate (J-integral) of a circumferential through-wall crack in a dissimilar metal (DM) weld subjected to tension and/or bending. In order to evaluate such cracks in a DM weld, the concept of a mixture ratio has been introduced, so that the existing single-material J-integral estimation method can be utilized with effective material strength properties which are the mixture of the two base metal properties with some ratio. The mixture ratio, however, is empirical, and several numerical analyses would be required to determine an appropriate value of mixture ratio. The new J-integral estimation method proposed in this study can take account of three material properties of the two base metals and a weld metal. Following the approach similar to the LBB.ENG2 method, the new method provides closed-form solutions for the J-integral by introducing an equivalent reduced thickness section replacing the cracked section in the DM weld. It is confirmed that the new method successfully degenerates to the existing one- and two-material J-estimation methods, when simulating one- and two-material crack problems. Furthermore, the maximum moments predicted by the proposed method, as a result of crack stability analyses, show good agreements with DM weld test results.
The path-independent J-integral and the crack-extension energy-release rate
