FE validation of R6 elastic-plastic J estimation for circumferentially cracked pipes under mechanical and thermal loadings

Objective: This paper provides validation of R6 elastic-plastic J-estimation methods, via elastic-plastic finite element analyses for circumferentially cracked pipes under combined mechanical and thermal loads. Materials method: In the FE analyses, the relative magnitudes of the mechanical and thermal loads, types of thermal loads, the crack sizes and material hardening are systematically varied. Loading sequence effects for the mechanical and thermal loads are also considered. The FE elastic-plastic J values are compared with those derived using R6 elastic-plastic J-estimation methods. Results: It is shown that there are significant load order effects on elastic-plastic J for large secondary stress cases, but these are conservatively estimated using newly proposed methods in R6.