The Gibson-Ashby model describes the three-stage compression behavior of cellular foams: elastic, plateau, and densification. The Deshpande-Fleck extension adds isotropic hardening to the plateau region, where the slope is controlled by hardening coefficient H.
References: Gibson, L.J., Ashby, M.F., "Cellular Solids: Structure and Properties", 2nd edition, Cambridge University Press, 1997. Deshpande, V.S., Fleck, N.A., "Isotropic constitutive models for metallic foams", Journal of the Mechanics and Physics of Solids, 2000.
Note: This interactive calculator shows typical foam behavior patterns. Use experimentally determined parameters for design calculations.