Modeling of Hypervelocity Impact of Sandwiched Open Cell Aluminum Foam

Abstract

Voronoi tessellation theory is applied to model cells and ligaments in an open aluminum foam material. Hypervelocity impact simulation is conducted using the smoothed particle hydrodynamics (SPH) solver in LS-DYNA. Finite element rebuild technique is applied based on the particle output for the fragmentation analysis. The modeling and simulation techniques are preliminarily verified by comparing the simulation results with testing results. The pressure wave propagation in the foam material, which is extracted from the simulation output, is very different from that in the homogeneous material. The simulation directly shows that the homogeneous aluminum panel is fully penetrated by the projectile while the aluminum foam sandwich panel, which has the same areal density, is not. The pressure wave generated in the homogeneous panel is more intensive and regular than that generated in the foam material. Besides, the pressure wave front is far ahead of the interface of the projectile and panel material in a homogeneous panel. Additional failure mechanism by tension-induced fragmentation due to the free surface reflection of the compressive wave on the rear surface is observed in the homogeneous panel, while this effect is not seen in the foam material counterpart. The ways that the pressure wave propagates in foam material play important roles in the better ballistic performance of the foam material.