Analysis of the elastic properties of open-cell foams with tetrakaidecahedral cells

Abstract

The elastic constants of an open-cell foam model, having tetrakaidecahedral cells on a BCC lattice, were found. The Young's modulus, shear modulus and Poisson's ratio were derived, as functions of the edge cross section and the foam density, by considering the bending, twisting and extension of the cell edges. If edge bending were the only mechanism the moduli would vary with the square of the foam density. The other deformation mechanisms are predicted to reduce the power law exponent by 3–5%, and the effect of edge torsion on the modulus level is small. The foam bulk modulus is predicted to vary linearly with its relative density, so Poisson's ratio approaches 0.5 at low densities. The lattice model is elastically isotropic, whereas other lattice models of foams are highly anisotropic.