Experimental investigation on against penetration of metallic honeycomb sandwich plates under low-velocity impact

The against penetration behavior of metallic honeycomb sandwich plates under low-velocity impact was experimentally studied with the drop-hammer impact systems. Damage modes and impact force-displacement responses of sandwich plates with different core thickness under the impact of blunt, spherical and cone projectiles were demonstrated. The effects of core thickness and projectile's shapes on the final fracture modes, impact force-displacement responses and critical fracture energy of sandwich plates were analyzed. Experimental results show that round-shear fracture mode, round-tensile fracture mode and diamondoid fracture mode were found on the top face-sheets of sandwich plates when the shapes of the projectiles are blunt, spherical and conical, respectively. Round-shear fracture mode, petaloid fracture mode and petaloid fracture mode were found on the bottom face-sheets of sandwich plates when the shapes of the projectiles are blunt, spherical and conical, respectively. Single peak modes were found in the impact force-displacement responses during loading of the spherical and conical projectiles on thin sandwich plates, while double peaks modes occurred when the sandwich plates were thick. For both thin and thick sandwich plates under the impact of the blunt projectile, the impact force-displacement responses accorded with double peaks modes. The ability against penetration of the thin sandwich plate appeared to be the best under the impact of spherical projectiles, while the worst under the impact of blunt projectiles. The ability against penetration of thick sandwich plates appeared to be the best under the impact of conical projectiles, while poorer under the impact of blunt and spherical projectiles.