Computational model for low cycle fatigue analysis of lattice materials : Incorporating theory of critical distance with elastoplastic homogenization

A novel numerical framework for low cycle fatigue analysis of lattice materials is presented. The framework is based on computational elastoplastic homogenization equipped with the theory of critical distance to address the fatigue phenomenon. Explicit description of representative volume element and periodic boundary conditions are combined for computational efficiency and elimination of the boundary effects. The proposed method is generic and applicable to periodic micro-architectured materials. The method has been applied to 2-D auxetic and 3-D kelvin lattices. The classical Coffin-Manson and Morrow models are used to provide fatigue life predictions (strain-life curves). Predicted fatigue lives for the auxetic lattice are shown to provide good correspondence to experimentally found fatigue lives from the literature.