Blast Resistance of Two-Stage Sandwich Panels with Homogeneous and Hybrid Core Configurations under High-Intensity Loading

Novel honeycomb sandwich panels have been investigated as a superior alternative to solid plates for blast protection. Earlier studies primarily focused on single-core-layer configurations; however, recent research has explored incorporating multiple-core layers to enhance blast resistance while maintaining the overall mass and volume of the panel. In the present numerical study, sandwich panels with two core layers separated by an intermediate sheetwere designed and subjected to dynamic blast loading, characterized in terms of an equivalent TNT charge mass (1-5 kg TNT), with a detonation point located 100 mm from the target structure. By combining circular and square honeycombs of Inconel-718 and stainless-steel alloy AL-6XN material in various ways, novel blast-resistant homogenous and hybrid core two-stage sandwich panels have been developed. The Johnson-Cook material model and ConWep blast simulation code was implemented for accurate blast simulation study. Comparative evaluation of the two-stage circular core steel model with the single-stage square core baseline design demonstrated a significant mitigation of 27% in back face deflection at 1 kg TNT blast load. Compared to the conventional single-stage square core design, Inconel-cored panels with double circular cores, circular top-square bottom cores, and square top-circular bottom cores achieved back-face deflection reductions of 79%, 69%, and 50% at 1 kg TNT, and 67%, 63%, and 61% at 3 kg TNT, respectively. Compared to the conventional existing two stage designs, the novel Inconel-cored, two-stage panel of double circular geometry, reduced the back face deflection by 68% at 1 kg TNT and 53% at 3 kg TNT, respectively. The inconel cored panels having double circular core arrangement, showed very minimal deformation even at higher blast loads of 4 and 5 kg TNT and improved the back face deflection by 60% at 4 kg TNT and, 55% at 5 kg TNT respectively compared to the conventional single stage square core design.