Fatigue life modelling under variable amplitude multiaxial loading: Comparison between fatigue criterion and incremental modelling

This study deals with fatigue of a 1045 carbon steel subjected to a cyclic tension-torsion spectrum combining in-phase and out-of-phase loadings and including overload, representative of an automotive chassis loading type. The experimental lifetimes are compared to the results of two different approaches. The first one combines a multiaxial fatigue criterion able to describe out of phase loading and a non-linear damage rule. The second one is based on an incremental mesoscale plasticity/damage model. It is shown that the criterion involving a non-linear damage rule is able to describe the experimental result for full spectrum (with overload) but the identification of the non-linearity is a function of spectrum type. The incremental approach gives better results for both spectra (with and without overloads) and does not need specific parameter identification.