High Velocity Impact on Sandwich Panels with Graded Foam-cored and Aluminum Face-sheet: Numerical and Experimental Assessment

In this research, the ballistic strength of sandwich structures with aluminum face-sheet and polyurethane foam cores of various densities have been investigated. The effect of graded changes in the density of foam core and arrangement of foamed layers with different densities on the absorption of energy and the ballistic limit of sandwich structures at high velocity (160-300 m/s) under the impact of semi-spherical nosed cylindrical projectiles were investigated. Generally, five different types of panels were designed in dimensions of 100×100 mm2, 6 in each. In total, the prepared samples were 30. Numerical simulations were performed, using Ls-dyna software. The results of this study showed that, firstly, there is good agreement between the experimental and simulation results and, secondly, the experimental and simulation results showed that the ballistic limit and energy absorption of sandwich structures of the same mass with the graded foam core in the case a less density foam layer is on the side of the impact for the three-layer panels is, respectively, 5.5% and 11.5% higher than the panel with single-layer foam core and average density.