Is it Possible to Get-Rid of S-N Curve for Fatigue Evaluation?: A Fully Mechanistic Model of 316SS Reactor Steel for Fatigue Life Evaluation

The present methods for fatigue life evaluation of nuclear reactor components have large uncertainties due to the overdependence on approaches that involve empirical fatigue life estimation, such as use of test-based curves of stress/strain versus life (S∼N) and Coffin-Manson type empirical relations. To reduce the uncertainty in fatigue life evaluation, we are trying to develop a fully mechanistic modeling approach. The aim is to capture the time/cycle-dependent material ageing behavior such as stress hardening/softening through multi-axial stress-strain evolution of the components based on which the life of the component can be predicted. In this paper, we introduce an implementation of the ANL developed evolutionary cyclic plasticity model for 316 SS reactor steel within the commercial finite element (FE) software ABAQUS. A user subroutine is developed to enable the incorporation of the ANL developed evolutionary cyclic plasticity model [1] into ABAQUS. The FE model, developed in this work, can be used for predicting the time-dependent stress hardening/softening of 3D structure. A strain-controlled constant amplitude fatigue experiment scenario is 3D modeled using the developed ABAQUS based FE modeling framework and is verified through experimental data.