Fast time-scale average for a mesoscopic high cycle fatigue criterion

Abstract

The paper discusses the lifetime prediction of structures in high-cycle fatigue based on the two-scale fatigue criteria of Dang Van type and several of its extensions in finite lifetime regime. The main assumptions for this criteria are (i) the material is polycrystalline and undergoes localised plasticity in one of the misoriented grains and (ii) crack initiation arises as a consequence of cumulated plasticity in this grain.\ud \ud The novelty of the presented approach is twofold. On the one hand a generalisation of mesoscopic plasticity model is presented, on the other a fast time scale average is introduced for tracking the cyclic material behaviour and the subsequent evolution of damage. The tracking method is based on the split between a quick quasi-periodic response of the system to the cyclic load and a slow evolution of the internal hardening and damage parameters of the material at the mesoscopic scale. The proposed method can be extended to a large class of local material behaviours involving not only plasticity, but also crack and damage evolution.\ud \ud The paper proposes a simplified plasticity-based model for the mesoscopic material behaviour and presents a comparison between predicted and experimental lifetimes. The results are discussed in terms of prediction capabilities and also in terms of the identification procedure of parameters of the mesoscopic model

Computational fretting fatigue maps for different plasticity models

“…Let us now analyse the boundary zone delimiting the preceding zones. This region experiences PS or RA while its fatigue criticality is negative, meaning infinite lifetime; this is in contradiction with experimental facts and Dang Van fatigue concepts . Moreover, one can equally remark that the zone has a weird border, which is difficult to accurately assess.…”

“…This region experiences PS or RA while its fatigue criticality is negative, meaning infinite lifetime; this is in contradiction with experimental facts and Dang Van fatigue concepts. [47][48][49] Moreover, one can equally remark that the zone has a weird border, which is difficult to accurately assess. Several arguments can be proposed for the outcome of the overlapping: the choice of the fatigue criterion and its application or the definition of the shakedown zones.…”

A shakedown analysis of high cycle fatigue of shape memory alloys

“…The homogenization assumptions relating the grain scale plasticity with the macroscopic behavior have been discussed in (Bertolino et al, 2007;Hofmann et al, 2009). They have permitted to extend consistently the criterion to finite lifetime (Bosia and Constantinescu, 2012;Morel, 2000a) as well as to explain the scatter of fatigue experiments and to explore the effect of loading path (Guerchais et al, 2014) to include the presence of stress concentrations created by defects (Guerchais et al, 2014). Moreover, the coherent thermodynamic foundation permitted to relate plastic dissipation with self-heating (Charkaluk and Constantinescu, 2009;Luong, 1998) and it opened innovative techniques for lifetime predictions (Doudard et al, 2004(Doudard et al, , 2007Poncelet et al, 2010).…”