Elastic Properties of Open-Cell Foams with Tetrakaidecahedral Cells Using Finite Element Analysis

A finite-element-method-based micromechanics has been used for predicting the orthotropic properties of open-cell foams that have tetrakaidecahedral unit cells. Foams with equisided and Kelvin-elongated tetrakaidecahedron as unit cells are studied. The results for elastic constants from the finite element models agree well with those of available analytical models. The struts were modeled using both Euler-Bernoulli and Timoshenko beam elements. It is found that classical beam theory overpredicts the elastic moduli when the struts have smaller length-to-thickness ratios. The effect of varying strut cross section on the elastic constants is studied. The variation is assumed to be such that the strut cross section gradually decreases from maximum value at the support ends to minimum value at the beam midsection. It is found that for the same relative density, foams with varying cross sections have much lower elastic moduli than foams with uniform cross sections.