Experimental ballistic performance analysis of add-on perforated armor plates

The use of innovative lightweight and multifunctional materials with different mechanical properties to provide the desired ballistic protection without compromising the armored vehicle's mobility and performance has become an important need. Add-on armor, which is composed of additional plates mounted on the body (aluminum or armor steel) or turret of an armored combat vehicle, is considered an important armor candidate recently. This type of armor can be applied using various technologies and materials to provide end-users with the highest level of protection against ballistic threats. This study aims to investigate the effect of the distance between two different perforated armor plates, hole diameters, spacing between holes and thickness and hardness of the materials of the perforated armor plates. Perforated plates made of high-hardness armor steel and manufactured according to MIL-DTL-46100 and MIL-DTL- 32332-CL2, were selected according to Stanag 4569 standards and tested for their ballistic performance against 12.7 x 99 AP armor-piercing ammunition (level 3+). According to the test results, it was found that increasing the distance between plates would reduce the probability of penetration, while the hole diameter and spacing between holes have a serious impact on the penetration and energy absorption capacity of the plate. Large hole diameters in perforated plates make them lighter but less resistant to penetration, while smaller hole diameters increase ballistic performance but also increase the total weight. No matter having small or larger holes, perforated armor plates defat the penetration by means of asymmetric forces causing the projectile to deviate from incident trajectory, projectile fracture, and projectile nose erosion. Thicker and high hardness armor plates show much better ballistic resistance against penetration on the expense of weight.