Reference
1. Gibson L.J., Ashby M.F. Cellular Solids: Structure and Properties. 2nd edition, Cambridge University Press, 1997.
2. Deshpande V.S., Fleck N.A. Isotropic constitutive models for metallic foams. Journal of the Mechanics and Physics of Solids. 2000;48(6):1253-1283.
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.