We propose a model of the structure is open porous material that allows you to set the configuration of the structural element allocated to describe the mechanical behavior of the material. As a result of analysis of deformation of the model determined according to the elastic characteristics poromateriala the volume fraction of solids. We also obtain an expression for the critical axial compressive stress, the corresponding loss of stability of the cell edges of the material. A method of describing the nonlinear deformation of the porous material of low density under uniaxial stress state. A comparison of the calculated dependence of c experimental data and the results of tests carried out by the authors of this paper.