Cross-identification isotropic/anisotropic damage and application to anisothermal structural failure

Cross-identification is an easy way to build confidence in a design solution for mechanical components, as it gives dif- ferent modeling possibilities for the same case study. As an example, phenomenological Lemaitre’s damage model is cross- identified on micromechanics based Gurson–Tvergaard–Needlemann (GTN) model. The equivalence is defined in terms of plastic response in tension but also of stress triaxiality effect. To the classical set of GTN parameters corresponds a set of damage parameters for Lemaitre’s damage law. High temperature materials behavior is then addressed by considering elasto-visco-plasticity coupled with damage, either isotropic or anisotropic. The models take into account the loading dependency of damage initiation conditions through a stored energy damage threshold. They allow with a single set of damage parameters for the calculation of the monotonic, creep and fatigue failure conditions. Closed-form expressions for the failure conditions define an equiva- lence procedure between both isotropic and anisotropic models. Final examples of application to anisothermal creep, creep–fatigue and to anisothermal structural failure illustrate the models abilities to deal with crack initiation conditions in case of complex thermomechanical loading.