Plastic yielding in cyclically loaded porous materials

The present paper focuses on plastic yielding of cyclically loaded porous materials. Unit cell models are employed to observe the evolution of the yield surface of porous materials under cyclic loading conditions. Non-linear isotropic as well as non-linear kinematic hardening matrix materials are considered. The yield surfaces computed with the unit cell models are compared to predictions of a micro-mechanical porous plasticity model that incorporates hardening. It is found that, in the case of kinematic hardening, the porous plasticity model underestimates the yield strength for larger hydrostatic stresses. An improvement of the model is proposed, so that a reasonable micro-mechanical approach to model porous materials under cyclic loadings is found.