Comparison of R6 and A16 J estimation methods under combined mechanical and thermal loads with FE results

Abstract

This paper compares elastic-plastic values of J calculated using the methods in the UK R6 and the French A16 fitness-for-service procedures with FE results for a vessel with a circumferential surface crack under axial tension and a radial thermal gradient. In the FE analyses, the relative magnitudes and loading sequence of mechanical and thermal loads are systematically varied, together with the material strain hardening exponent. Fully circumferential and semi-elliptical surface crack with two relative crack depths are considered. It is found that the R6 estimates are overall accurate but can be non-conservative at large L-r. The A16 estimates are more conservative than the R6 estimates at small L-r but are conservative even at large L-r. Possible sources of conservatism and non-conservatism in R6 and A16 are discussed. (C) 2015 Elsevier Ltd. All rights reserved.