THE DEVELOPMENT OF UHMWPE PROTOTYPE HELMETS FOR IMPROVED BALLISTIC MASS EFFICIENCY

摘要

The Army has made strategic use of light-weight composite materials in body armor. The PASGT helmet system, for example, allowed the transition from historically metallic (e.g., steel) materials to fiber reinforced composites. The success of fibers such as Kevlar (aramid) enabled significant improvements in ballistic mass efficiency - a metric used to quantify the ballistic resistance of a material on a per unit weight basis. However, other fibers have also enjoyed success in personnel protection systems, both domestically and abroad. These include ultrahigh molecular weight polyethylene (UHMWPE) such as Dyneema (Holland), Spectra (USA), and Sansei (Japan) for example. The purpose of the present research is to explore the materials and processing issues associated with using UHMWPE in helmet applications, with specific emphasis on meeting a variety of impact and structural criteria. These materials have a relatively narrow processing window (around 250 deg F) and for optimal performance require relatively high pressures (approaching 3000 psi and above). Properly applying heat and pressure uniformly throughout a helmet cavity is critical, but highly dependent on tool design, preform stacking and discontinuities, and thermal influences during consolidation (e.g., slippage of fabric). Results will be presented that detail the use of hybridization schemes to augment the relatively poor structural properties of UHMWPE, as well as novel approaches to preforming, debulking, and consolidating these materials. It will be shown that these materials are excellent candidates to deliver various levels of high velocity impact resistance that can enable further performance benefits in protective helmet systems.