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

•This paper provides validation of R6 J-estimation methods for combined mechanical and thermal loads.•In FE analysis, relevant parameters are systematically varied.•Loading sequence effects for the mechanical and thermal loads are also considered.•Significant load order effects for large secondary stress cases are successfully treated by methods in R6.

ObjectiveThis 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 methodIn 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.ResultsIt 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.