Fiber volume Fractions for thermoplastic helmet
Recently disclosure which includes helmet liners and helmet with deflective structures and helmets with thermochromic features was made possible. The personnel armor system ground helmets have been replaced with advanced combat helmets; however delivering the safe, durable, robust helmets with light weight is a challenge but cost and high performance remain to be the driver for thermoplastic technology. Embodiment of the present disclosure includes making a long fiber thermoplastic structure that includes hot melt impregnating a continuous reinforcing fiber with thermoplastic matrix to form a continuous tow, cutting the continuous tow into pellets forming a discontinuous reinforcing fiber from cutting a continuous reinforcing fiber and feeding of the plurality of pellets to the structure thus forming long fiber thermoplastic. Therefore helmet among other disclosures includes a continuous fiber material, and a polymer, wherein polymer is chosen from a thermoplastic polymer and thermoset polymer.
Softer materials are being used on the body of the outer shell of the army helmet due to the requirement of enhanced ballistic performance. The softer shell influences the ear to ear crush resistance of the helmet. Carbon fiber reinforced polyacrylamide and poly phenylene sulfide long thermoplastics have been used to design and fabricate a rim stiffened liner for the helmet outer shell used by the army. Fibers used in making bulletproof vests and helmets include polyphenylenediamine terephthalamide and graphite fibers which are embedded in the composite material. Armor materials best used have higher strength, higher melting point and higher modulus.
Resent invention of impact resistant helmet made of impact resistant composite shell which comprises of plurality of prepreg packets, have been known in this art. Further attempts are made to improve the resistance and ballistic of the army helmets, and also to be able to design the composite using reinforced fabric cut from flat sheets which must be formed in a spherical shape of helmet. The military helmets are also made from two high tenacity fibers in multiple layers, where the fibrous materials are in layers of network resin matrix. The outer layer of the helmet is formed from aramide fibers and the inner fibrous layer is made from high tenacity polyolefin fibers. A third layer of fibrous material can be added as the helmet shell, this is formed from glass fiber also in resin matrix thus making the helmet light in weight, excellent ballistic resistance properties and useful for army application.