A multiscale high cycle fatigue approach based on shakedown and cohesive zone theories—Application for additive-manufactured 316L steel

A high cycle fatigue (HCF) approach based on shakedown, crystal plasticity and cohesive zone theories is developed for metals. To take into account the effect of localized plasticity in grains and grain boundaries, crystal plasticity and elastoplastic cohesive zone models are considered to calculate the mechanical responses of grains and grain boundaries at the mesoscopic scale, respectively. The Papadopoulos fatigue criterion is used to gauge the fatigue property of the grain, and a new mesoscopic fatigue criterion, based on the shakedown theory as in the Dang Van criterion, is proposed to assess the fatigue performance on the grain boundary. Based on these two fatigue criteria, the effects of dislocation slip and grain boundaries, as dominant crack initiation features in 316L steel, are explored. To validate the approach, comparison between the fatigue properties of additive-manufactured (AM) 316L steel manufactured with the different process parameters has been carried out. The simulation results show very good correlation with the experimental ones obtained by the self-heating method. The proposed approach can be used to optimize the fatigue properties of AM steel with respect of the process parameters.