High Strain Extension of Open-Cell Foams

The high strain tensile deformation of open-cell foams is analyzed, using a Kelvin foam lattice model. The stretching, bending, and twisting of elastic cell edges is analyzed, and the deformed cell shapes predicted. The stress-strain relation and Poisson’s ratio are predicted for strains up to 40% for tension in the [100] and [111] directions of the BCC lattice. The latter prediction is closest to stress-strain curves for polyurethane foams, especially when the cell shape anisotropy is taken into account. The change from edge bending to extension as the main deformation mechanisms, for strains exceeding 20% increases the slope of the stress-strain curve. A comparison is made with irregular cell structure models. [S0094-4289(00)01001-X]