Influence of target dynamics and number of impacts on ballistic performance of 6061-T6 and 7075-T6 aluminum alloy targets

The effect of target condition (static and dynamic) and number of projectile impacts (single and multiple) on the ballistic performance of 6061-T6 Aluminum alloy, 7075-T6 Aluminum alloy and 6061- aluminum alloy Fiber Metal Laminates (FML) have been investigated. Both numerical and experimental approaches were used to predict the nature of target deformation and its kinetic energy absorption. Ballistic experiments were conducted using armor piercing projectiles (APP) of diameter 7.62 mm with velocities ranging between 330 to 450 m/s. Irrespective of the target material (6061-T6 aluminum alloy, 7075-T6 aluminum alloy), non-linear reduction of exit velocity of the projectile was observed for a single plate target. In contrast, large plastic deformation and 'petaling' mode of failure was observed for the FML and rubber sandwiched targets. Higher impact energy absorption of the FML target and rubber intruded 7075-T6 aluminum alloy plates is mainly due to the additional resistance offered by the individual layer of metal and fiber. In addition to projectile velocity, when the target (7075-T6 aluminum alloy plate) velocity was varied in the range of 10 to 40 m/s, significant reduction in exit velocity of the projectile was observed compared to static target. This is due the fact that, moving target has altered the penetration behavior of the projectile and additional increase of target velocity caused 'ricochet' of the projectile. In addition, when the target was subjected to multiple projectile impacts, gradual reduction of ballistic performance was observed. Communicated by Kuang-Hua Chang.