Type of Document Thesis Author Lim, Alvin Author's Email Address email@example.com URN etd-08152007-120935 Title Fabrication of Lightweight Composite Small Arms Protection Insert Degree Master of Science Department Industrial and Manufacturing Engineering, Department of Advisory Committee
Advisor Name Title Okenwa Okoli Committee Chair Ben Wang Committee Member Richard Liang Committee Member Keywords
Date of Defense 2007-07-05 Availability unrestricted AbstractNon-metallic materials such as ceramics are an accepted method to produce armor systems due to their low density, high hardness, high rigidity and strength in compression. Due to ceramicís low fracture toughness and the tendency of fracturing when subject to high tensile stresses, a back-plate of a more ductile material such as aluminum, steel or fiber reinforced plastics have be used to keep the laminate intact when subjected to a projectile impact. Ceramic plates have the ability to initially slow down the bullet; then break it down into smaller fragments, but are not meant to fully stop the projectile. The ceramic plate reduces the bullets capacity to penetrate and transfer the kinetic energy from the projectile to the plate. This disperses the energy throughout a larger area thus absorbing most of the impact energy. The ceramic plate requires a backing plate for support to compensate for the brittle nature of the ceramic materials. The backing plate must be capable of containing any stray fragments and absorb some of the residual energy. The downside to this system is the total weight of the system is too large.
Fiber reinforced composites have been used increasingly to replace heavier metal structures because of their high stiffness to weight ratios, corrosion resistance, damage tolerance, and functional integration. As such, new advanced fiber composites are now replacing aluminum components in the aerospace industry. Furthermore, the failure modes of composites promote pronounced energy absorption especially under high speed impact loading. This attribute has made composites valuable materials for the defeat of projectile impact and they are now increasingly being used in personnel armor like the Small Arms Protection Insert (SAPI).
The current work stems form the need of the US Air Force Pararescue Jumpers (PJ). Their current SAPI equipment is a pure polymer (UHMWPE) solution that defeats the 7.62 mm rounds at muzzle velocities over 2500 ft/sec. They are however thick and heavy, making their use rather precarious in some instances. As such, a thinner, lighter and durable system is desired that retains the same properties as the current system.
This work set out to investigate the viability of producing thinner and lighter cost effective plates for the defeat of the 7.62 mm rounds at muzzle velocities and criteria set by the PJSAPI specifications. The manufacturing of these plates could have a large impact on the performance of the material. Preliminary tests show that the increase in pressure applied to the laminate can increase the overall performance with a decrease in the overall weight of the system.
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