Issam Doghri

Elasticity and Viscoelasticity of Open Cellular Material: Micromechanical Approach

Cellular materials are characterized by remarkable mechanical properties with light weight. Such materials are used in various applications mainly in energy absorption. Their microstructure are described by two major families : open and close cell foams. This paper deals with the prediction of the macroscopic behavior of open cell foams in elasticity and viscoelasticity as function of their microstructure. Firstly, we use a micromechanical model based on Cosserat homogenization framework. Secondly, Finite Element (FE) computations are performed on a unit cell subjected to periodic boundary conditions. The results are confronted to various models developped in litterature. Finaly, the linear viscoelastic behavior is deduced from elastic results by taking advantage of correspondence principle.

Micromechanical Modeling of Porous Solids

In this paper, we focus on the prediction of the elastic and linear viscoelastic properties of porous solids based on their microstructure for the entire range of porosity. Both analytical models, namely Mean Field theory for porous solids and beam theory for cellular solids, and Finite Elements method are used and the corresponding results are compared. For low porosity, Mean Field models yield good predictions. However, when increasing the void concentration and the pores become macroscopically interconnected, only the Differential Method continues to give good estimates. The potential of Mean Field models suitable for highly porous solids to predict the response of cellular materials is also investigated.