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The mechanical properties of open cell structures made from an elastic-plastic bulk material are investigated by Finite Element simulations. The influence of structural irregularities on elasto-plasticity and deformation localization of open cell structures is analyzed. Six regular three-dimensional generic structures with a relative density of 12.5% are modeled by a unit cell approach for predicting the entire tensors of elasticity. From these six structures the two structures with the lowest and the highest elastic anisotropy are selected for further studies, introducing various degrees of structural irregularities. The effect of these irregularities on the linear and nonlinear behavior as well as the influence on the deformation localization is studied employing finite sample models. Results are presented by means of the direction dependent Young's moduli, deformation plots, overall stress-strain curves, and histograms of the energy distribution.

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The present paper aims at computational simulations of particle reinforced Metal Matrix Composites as well as parts and specimens made thereof. An incremental Mori-Tanaka approach with isotropization of the matrix tangent operator is adopted. It is extended to account for large strains by means of co-rotational Cauchy stresses and logarithmic strains and is implemented into Finite Element Method software as constitutive material law. Periodic unit cell predictions in the finite strain regime are used to verify the analytical approach with respect to non-proportional loading scenarios and assumptions concerning finite strain localization. The response of parts made of Metal Matrix Composites is predicted by a multiscale approach based on these two micromechanical methods. Results for the mesoscopic stress and strain fields as well as the microfields are presented to demonstrate to capabilities of the developed methods.