Linear and Nonlinear Numerical Investigations of Regular Open Cell Structures

Linear and nonlinear Finite Element simulations of various regular three-dimensional cellular solids (lattice structures) with relative densities ranging from 10% and 20% are presented. The structures consist of polymeric struts with circular cross sections. Two different Finite Element modeling techniques are employed. Beam element based models and continuum element based models are utilized and their applicability is assessed. Beam element based models compromise about the numerical model size and the detail resolution of the problem. Continuum element based models are used for highly detailed unit cell analyses. For simulations of the overall behavior the structures are treated as infinite media by a periodic microfield approach. The entire overall elasticity tensors are computed for the constitutive characterization of the effective mechanical behavior of the micro-structures. Overall stress-strain curves are predicted for uniaxial compressive loading, taking into account finite strains and elasto-plastic strut material. The predicted properties are evaluated with respect to direction dependence and density dependence. Finite samples of specimens are modeled for comparison to experimentally obtained results.