Analysis of experimentally assessed EVA foams with mixed solid-shell elements capable of very large strains

We analyze, both experimentally and numerically, two EVA foam specimens with densities ρ=120kg/m3 and ρ=220kg/m3. In the numerical analysis, we use our recent finite strain element formulations based on least-squares strains (in both solid-shells and full three-dimensional discretizations). The Ogden-Hill hyperelastic model is coupled with a one-term standard solid containing a Maxwell element. Compression experiments are performed to evaluate the Ogden-Hill properties for the two EVA foams. Viscous properties are obtained from interpolation of creep results reported by R. Verdejo. An exponential integration of the internal variables (which have the role of back-stresses) is proposed along with the complete description of the constitutive system. The classical analysis of the acoustic tensor is also performed for the measured properties. Four benchmark examples are introduced.