Mesoscopic modelling of the dynamic compaction of a polymeric foam

The use of polymeric foams is widespread in many industrial fields as shock wave mitigators. Indeed, they are lightweight materials with an excellent weight/stiffness ratio and low production costs. One of the applications of interest to the CEA is the protection of structures against mechanical loadings generated by laser irradiation or high velocity impact of small debris. The search for the optimal size and shape of porosities are essential data for improving the mitigation ability of foams. The purpose of this study is to simulate the dynamic behavior of a polyurethane foam subjected to different dynamic loadings at various strain rates, using a mesoscopic model. The foam was modeled in different ways in 2D: first by periodically arranging cylindrical porosities in the polyurethane matrix in a linear manner with boundary conditions, then in a staggered manner, and finally randomly. The matrix was modeled using an equation of state and a constitutive law of dense polyurethane. Comparisons between experiments and calculations were made on velocity profiles obtained by PDV on the rear surface of foam samples. Calculations fairly reproduce experiments and show the influence of the arrangement of porosities on the foam compaction.