of Spectra fabrics. Prosser et al.17 observed a temperature increase on the back surface of a ballistic panel containing 40 layers of nylon fabrics to as high as 76.6°C after perforation by a .22 caliber projectile.
CONCEPTS FOR ENHANCING BALLISTIC PERFORMANCE OF FABRICS
There is an opportunity to develop new fibers, coming up with entirely new methods of processing fibers that eliminate defects, and to make fibers from other desirable materials. Magnesium, with a density of only 1.7 g/cm3, is an example of such a desirable material. The tensile strength of most magnesium alloys is in the range 200 MPa to 400 MPa.18 Alumina fiber, with a tensile strength of 1.7 GPa, is the high-performance fiber with the lowest tensile strength. Thus the development of even 1 GPa tensile strength magnesium fiber that could be used to replace bulk magnesium alloy in helmets with a magnesium alloy and Spectra fiber construction could be significant.
In carbon-nanotube-reinforced composites, polymers such as poly(paraphenylene terephthalamide), poly(benzobisoxazole), poly(diimidazo pyridinylene [dihydroxy]phenylene), ultrahigh-molecular-weight PE, polyurethane, and so on can be used as a matrix system, with the carbon nanotube as the reinforcing entity. Similarly, carbon-nanotube-reinforced fibers can also be made from metals, ceramics, and glasses, wherein during high-temperature processing there exists the probability of compound formation and new types of interfacial bonds.
17Prosser, R., S. Cohen, and S. Cohen. 2000. Heat as a factor in the penetration of cloth ballistic panels by 0.22 caliber projectiles. Textile Research Journal 70(8):709-722.
18Mathaudhu, S., and E. Nyberg. 2010. Magnesium alloys in army applications: Past, current and future solutions in magnesium technology. Pp. 27-33 in Magnesium Technology 2010: Proceedings of a Symposium Sponsored by the Magnesium Committee of the Light Metals Division of TMS, 2010. Warrendale, Pa.: Minerals, Metals, and Materials Society.