Mesoscopic modelling of the dynamic compaction of a polymeric foam

Polymeric foams are widely used in many industrial fields as shock wave mitigators. They can be, for instance, interesting materials for the protection of structures against intense and brief mechanical loads. According to the literature, there are several models representing the macroscopic mechanical behavior of porous materials, but few take into account a direct influence of the microstructural parameters. However, the search for the optimal size and shape of porosities, and their distribution are essential data to improve the mitigation ability of foams. This article presents several 2D mesoscopic numerical models to study the dynamic behavior of a polyurethane foam subjected to plate impact loadings. We assume a linear periodically arranged circular cells structure, a staggered circular cells structure and a scattered distribution of circular cells. The matrix is made of solid polyurethane with a dynamic behavior represented using an equation of state and an elastoplastic constitutive law. Numerical computations of two plate impact experiments were performed. Velocity profiles measured by a VISAR at the rear surface of the foam and computed results obtained from a 2D Euler code are compared. Elastic precursor and compaction wave propagations through the foam are fairly well reproduced by models based on regular and staggered arrangements of cells. Experimental results are not better reproduced by using the model which assumes scattered circular cells.