Impact Response of Compression–Torsion Lattice Structures Under Underwater Shock Wave Load

Compression–torsion lattice structures (CTLS) exhibit coupled compressive–torsional deformation, yet their response under underwater shock loading remains to be further investigated. In this study, sandwich structures with CTLS cores were investigated through a combination of shock tube experiments, digital image correlation (DIC), and nonlinear finite element analysis. The underwater shock response and protective performance were evaluated based on rear-plate kinetic energy, central deflection, and plastic deformation. The results indicate that, at the same relative density, CTLS sandwich structures reduce the rear-plate kinetic energy by more than 42% and the peak deflection by 12.4%, compared with sandwich structures employing traditional straight lattice structures (TSLS). Under identical compressive stiffness, CTLS provide superior protective performance to TSLS, and this advantage becomes more pronounced with increasing ligament diameter. Furthermore, CTLS sandwich structures extend the tunable range of the core energy absorption ratio from 33–35% to 24–38%, reflecting enhanced flexibility in energy distribution within the structure.