Multilayered armors with a front ceramic followed by aramid fabric (Kevlar™) are currently used against high velocity ammunition. In these armors, a front ceramic layer that shatters and spalls the bullet is followed by an intermediate layer, usually plies of aramid fabric, which dissipates both the bullet and ceramic fragments energy. In the present work, the intermediate aramid fabric layer was replaced by an equal thickness layer of 30 vol% jute fabric reinforced epoxy composite. Ballistic impact test with 7.62 caliber ammunition revealed that both the plain epoxy and the jute fabric composite have a relatively similar performance of the Kevlar™ and also attended the NIJ standard for body protection. The energy dissipation mechanisms of jute fabric composite were analyzed by scanning electron microscopy and found to be the rupture of the brittle epoxy matrix as well as the interaction of the jute fibers with the post-impact fragments. This latter is the same mechanism recently disclosed for aramid fabric. However, the lightness and lower cost of the jute fabric composite are additional advantages that favor its substitution for the aramid fabric.
The ballistic performance of a multilayered armor with a front ceramic tile backed by a plate of giant bamboo fiber reinforced epoxy composite was assessed. The ceramic layer spalls the projectile, while the bamboo composite dissipates the remaining energy. Ballistic tests were performed with high velocity ammunition and the projectile penetration was evaluated by the intrusion depth in a clay witness. The average depth value of near 18 mm was found well below the limit specified by the NIJ standard of 44 mm and better than that for aramid fabric composite, about 22 mm, with the same thickness of the giant bamboo composite. The giant bamboo composite acts as an efficient barrier for the fragments originated from the ceramic brittle rupture. For practical application in portable armor for personal protection, the layer of giant bamboo composite presents not only a superior ballistic performance but also lightness and economical advantages over the conventional aramid fabric.
1 October 2018 in Journal of Materials Research and Technology