Fragmentation of an armour piercing projectile after impact on composite covered alumina tiles
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In a typical body armour system, a hard armour plate is often used in conjunction with a soft ballistic panel. The main purpose of the armour plate is to erode and fragment an impacting projectile, such as 7.62 mm armour piercing (AP) projectiles with a very hard material core. This is made possible by employing a single ceramic tile as the strike face. This tile is covered by a sheet material. The sheet cover may improve the ballistic performance by partly maintaining the integrity of the ceramic. In this study, the effect of adding a composite cover has been investigated experimentally by ballistic testing of different types of composite-covered targets. The targets were totally perforated by a 7.62 mm AP hard steel core projectile at near-muzzle velocities (around 800 m/s). The post-impact process was monitored by high speed video, and the resulting core fragments were collected and analysed. This allowed the core fragmentation, residual velocity and kinetic energy-loss to be quantified. The results showed that the core fragmentation and the kinetic energy-loss of the projectile were most significant for the targets with the composite-cover on the back of the alumina. For targets with four composite back-layers, and an increased areal density of 9.5%, the mass of the projectile core was reduced by 61%, while the kinetic energy was reduced by 84%. The residual velocity did not vary to the same extent between the different target configurations. The mechanism behind the positive effect of a back cover is believed to be delayed opening of tensile cracks that originate from the back of the ceramic, which gives more time for interaction with the penetrator.
Rahbek, Dennis Bo; Johnsen, Bernt Brønmo. Fragmentation of an armour piercing projectile after impact on composite covered alumina tiles. International Journal of Impact Engineering 2019 ;Volum 133. FFI