Tests and numerical simulation for anti-penetrating behavior of a high strength 7A04-T6 aluminium alloy plate against a blunt projectile's impact

Target-shooting tests for a 5.98mm diameter rigid blunt projectile penetrating a 6mm thick 7A04-T6 aluminum alloy target plate were conducted in a one-stage gas gun with an impact velocity range of 73.9-446.5 m/s to learn the anti-penetrating behavior of high strength aluminum alloy against a kinetic energy projectile's impact. The projectile's residual velocity after perforating the target plate and the fracture behavior of the target plate were recorded. After fitting the projectile's initial velocity-residual one data, its ballistic limit velocity was obtained. Meanwhile, the numerical target-shooting simulation was conducted by using a 3D finite element model built in ABAQUS/Explicit. The mechanical behavior of 7A04-T6 aluminum alloy was described with Johnson-Cook constitutive model and the modified Johnson-Cook fracture criterion. The test results showed that the high strength 7A04-T6 aluminum alloy plate under a blunt projectile's impact has a shear plug and obvious cracks can be observed on the surface of the plug; the ballistic limit velocity is 156 m/s, the shear plug appears when the impact velocity is not less than 90% of the ballistic limit one. The numerical simulation indicated that the finite element calculation can reproduce the target plate's shear plug and the fracture behavior on the surface of the plug; the predicted ballistic limit velocity is 168.8 m/s, it is 9% larger than that obtained in the test; the shear plug occurs when the impact velocity is not less than 92% of the ballistic limit one, this result is very close to the test one.