Application of a ΔJ Approach for Thermal Fatigue Crack Growth Assessment on the Large Scale Yielding PACIFIC Experiment

Austenitic stainless steel large nuclear components, with high thicknesses, may experience cyclic Large Scale Yielding due to mechanical and thermal loadings during their service life. International codes and standards only provide inadequate and very conservative methods for dealing with the thermal fatigue crack growth associated with this situation. Non-codified alternatives, such as ΔJ approaches, then appear to be good candidates for predicting fatigue crack growth beyond Small Scale Yielding. This paper aims to apply a ΔJ approach on the so-called PACIFIC experiment permitting thermal fatigue crack propagation in Large Scale Yielding conditions. Numerical protocol and modelling assumptions are detailed. Then, a particular focus is given, through sensitivity analyses, on the choice of the cyclic elastic-plastic stress-strain curve used in the Finite Element Analyses. Finally, comparisons between numerical results and experimental fatigue crack growth data are provided and discussed.