Numerical evaluation of curved sandwich structures performance with hexagonal cores under air-blast loading

This study investigates the mechanical response of metallic sandwich panels to explosive loading, with a focus on the synergistic effects of honeycomb core geometry and front-face curvature. A numerical model was developed in ABAQUS/Explicit to simulate the detonation of TNT charges (up to 3 kg) at a fixed standoff distance of 100 mm. The AL6XN stainless steel was modeled using the Johnson–Cook constitutive law to account for strain-rate sensitivity and plastic deformation. The model was validated against experimental data, and a parametric study was conducted to analyze the influence of core geometry and curvature. The results revealed that a hexagonal core combined with a front-face curvature exceeding 30° to 45° provides optimal performance, characterized by enhanced energy absorption, reduced stress concentrations, and a more uniform plastic strain distribution. In contrast, a limited curvature of 15° resulted in unstable wave propagation and reduced structural integrity. The adopted performance indicators—including the Energy Absorption Efficiency (EAE), and Overall Structural Efficiency Index (OSEI)—consistently confirmed the superiority of these curved configurations. Notably, these significant enhancements in blast resistance and structural efficiency were achieved without any increase in mass, underscoring the mass-efficiency of the proposed design. These findings advocate for the use of hexagonal honeycomb-core sandwich panels with moderate-to-high curvature in blast-resistant applications, particularly in the aerospace, defense, and critical infrastructure sectors where lightweight, high-performance passive protection is required.