Blast Response and Multi-Objective Optimization of Stretching–Bending Synergistic Lattice Core Sandwich Panels

Sandwich structures with lattice cores are promising for blast protection, yet conventional uniform lattices (ULs) often exhibit limited energy absorption under impulsive loading. This work introduces a novel sandwich panel containing Stretching–Bending Synergistic Lattice (SBSL) cores, and the blast-resistance performance is investigated by finite element modeling (FEM). The results show that the areal specific energy absorption (ASEA) of the SBSLs cored with the same relative density exceeds that of ULs cored by up to 20%. Compared to the cored ULs, the cored SBSLs exhibit significant enhancements in total energy absorption (EA), with improvements of up to 8% for the core itself and 54.7% for the front face plate. Furthermore, the effect of geometric parameters on blast performance is systematically analyzed. The results indicate that reducing the rod diameter of the core cell and thickness of the face plate contributes to higher ASEA, while decreasing the cell height and thickness effectively suppresses the maximum instantaneous displacement (MaxD) of the back face plate. Finally, to further improve the performance, multi-objective optimizations are carried out. The results show that, compared with the baseline model, the MaxD of the optimized structure is reduced by 45%, while the ASEA is increased by 23%. This study demonstrates the significant potential of the SBSL core sandwich panel on blast-resistant protection applications.