BENCH-KJ: BENCHMARK ON ANALYTICAL CALCULATION OF FRACTURE MECHANICS PARAMETERS K_I AND J FOR CRACKED PIPING COMPONENTS - FINAL RESULTS AND CONCLUSIONS

摘要

For most of design codes and for ageing consideration, fracture mechanics is needed to evaluate the integrity of cracked components. The major parameters used in this kind of analysis are K and J. In this frame, different international codes (RSE-M appendix 5.4, RCC-MRx appendix A16, R6 rule, ASME B&PV Code Section XI, API 579, VERLIFE, Russian Code...) propose compendia for stress intensity factors, and, for some of them, compendia for limit loads for usual situations, in terms of component geometry, type of defect and loading conditions. The benchmark « bench-KJ », proposed in the frame of the OECD/IAGE Group, aims to compare these different estimation schemes regarding of in comparison to available reference results done by Finite Element Method for representative cases (pipes and elbows submitted to mechanical or/and thermal loadings, considering various type and size of cracks). Twenty-nine partners are globally involved in this benchmark, the level of their contribution depending on the considered technical task. The benchmark covers simple cases with basic mechanical loads like pressure and bending up to complex loading combinations, but also complex geometries (pipes and elbows) including cladding or welds; all these cases are classified into 6 technical tasks: elastic stress intensity factors calculation (task 1), J calculation in cracked pipes (tasks 2 and 3), then in cracked elbows (task 4), and finally J in some particular cases (task 5) and in weld (task 6). This paper presents the final results of the benchmark in terms of global comparison between different codes.