Approximate J estimates for circumferential cracked pipes under primary and secondary stresses

This paper presents finite element solutions for elastic-plastic J for circumferentially cracked pipes under combined mechanical and thermal loads in terms of the V/V_o factor used within the failure assessment diagram approach. Systematic analyses suggest that the two major variables affecting V/V_o are the relative magnitude of the secondary stress and the primary load magnitude. It has been found that the variations with these parameters obtained from the FE results agree well with current R6 predictions for modest thermal loads and low primary loads. For larger thermal stresses, the R6 predictions are overly conservative and more accurate predictions are suggested.