Dynamic response of the S-shaped composite foldcore sandwich structure under high-velocity impact loads

The dynamic response of the S-shaped foldcore sandwich structure was investigated at high-velocity impact load by combining the experimental and numerical methods. The ballistic tests were performed with a blunt projectile at different velocities, ranging from 49.7 m/s to 154 m/s, and the ballistic limit velocity (BLV) was estimated. The test results show that the impact location exerted great influence on the failure modes and energy absorption of the core. The BLVs of the sandwich structure are 64.2 m/s and 56.2 m/s for node and base impacts, respectively. And the different modes are observed for the top face sheet, the core and the bottom face sheet. The corresponding numerical simulations were performed by using Abaqus finite element software. The simulation results show that the BLVs predicted by the simulation correlated well with the tests. The failure modes of the sandwich structures with fiber fracture, delamination and compression failure are predicted reasonably. For the node impact conditions, the absorbed energy of the core is significantly higher than that of the top and bottom face sheet. For the base impact conditions, there is no significant difference on the energy consumed for three components of the structures.