Advanced prepreg ballistic composites for military helmets

With the advancement of ballistic materials and technologies, the ballistic prepregs are becoming an essential construction technique for getting the maximum performance out of the high performance fibers. The ballistic prepregs help to maximize the engagement between fibers and high speed projectiles penetrating the ballistic material, thus reducing the amount of ballistic material required to defeat the projectiles. The backbone of lightweight ballistic materials is high performance ballistic fiber. However, the ballistic fibers alone cannot engage a high speed projectile because the projectile can push fibers aside without breaking a single filament in the fiber bundle. To overcome this limitation, the fibers are converted into either a woven fabric or a non-woven material such as a cross-plied unidirectional material. These ballistic materials have fibers in at least two directions which forces the projectile to engage with the fibers by keeping them in place with either thermosetting or thermoplastic polymeric matrix. However, for rigid armor, these prepregs are molded into helmets by utilizing proper molds and molding conditions. In the current paper we highlight the important factors that affect the combat helmet performance such as: fabrication methods, mechanism of ballistic energy absorption, ergonomic aspects of ballistic helmet design and materials systems. Special emphasis is given to thermoset and thermoplastic ballistic composites. Wherever appropriate, in the context of the topic, we refer to our experience in working on the development and serial production of the first ballistic helmet for former JNA (Yugoslav People’s Army) Keywords: prepreg, fibers, helmets, ballistic composites