Yield and buckling behavior of Kelvin open-cell foams subjected to uniaxial compression

This study analyzes the yield and buckling behavior of Kelvin open-cell foams subjected to uniaxial compression. A homogenization theory of the updated Lagrangian type is applied to cubic unit cells and cell aggregates in the Kelvin foam model. Macroscopic instability and microscopic bifurcation are thus incrementally examined under uniaxial compression. The analysis is performed by taking into account the non-uniformity of strut cross-sectional areas and the strain hardening–softening behavior of struts that were observed in experiments on open-cell 6101-T6 aluminum alloy foams. It is shown that macroscopic instability primarily occurs as a consequence of the strain hardening–softening behavior of struts. It is further shown that the macroscopic instability stress obtained has (3/2)th power dependence on relative density as predicted in the Gibson–Ashby relation.