Investigation on the ballistic resistance of double-layered A3 steel targets against blunt projectile impact

Steel plates are widely used to construct resistant structures, and a lot of literature report on the ballistic resistance of metallic monolithic target. However, few reports can be found for double-layered target (DLT), especially the one with large gap space. Experimental study was conducted on the DLTs of both in contact (I-DLT) and with 200 mm gap space (S-DLT) by using a gas gun to fire blunt projectiles. Each DLT was made of two A3 steel plates with the thickness of 5 mm. From the experiments, initial-residual velocity curves were obtained. The experimental observations are as follows. Firstly, both configurations of DLT suffer from shear plugging. Secondly, the ballistic limit of I-DLT is 1.92 times of that of 5 mm thick monolithic target. Thirdly, the ballistic resistance of S-DLT yield to large divergence. The large divergence, according to the high speed photograph and the recovered targets, is caused by the two classical different trajectory statuses of the projectile after perforation of the first plate. Fourthly, there are two ballistic limits for S-DLT. Finally, the ballistic limit of I-DLT is close to or greater than that of S-DLT. Parallel numerical simulations were conducted by ABAQUS/EXPLICIT, and the experimental phenomena and results were well predicted.