9 - A newly developed bulletproof vest using kenaf–X-ray film hybrid composites

Abstract

Bulletproof vests are either too heavy or too expensive. Therefore, for more effective performance and comfort for the user, a lighter and cheaper bulletproof vest is desirable. This chapter discusses the tensile and flexural characteristics and high-velocity impact properties of a new composite material aimed to replace the current insert plate for existing available bulletproof vests or body armor. In this design, materials used are a natural fiber (kenaf) and x-ray film. Using the traditional hand lay-up method, the materials were fabricated into different configurations with seven layers each. The mechanical characteristics for these four configurations were then determined through tensile and flexural testing. The most outstanding configuration was selected based on the mechanical characteristics obtained and was enhanced with more layers. This improved configuration was then tested using the high-velocity impact test. Using a single-stage gas gun, the specimen was tested by varying the gas gun pressure, which resulted in different readings of the bullets' velocity. Three types of bullets were used: blunt or flat, conical or chisel-pointed, and hemispherical. Results showed that the designs enabled the material to absorb some impact energy because it was able to bounce back bullets shot with speed up to 105m/s. However, because ballistic tests use bullets faster than the high-velocity impact test, improvement is still needed for the materials to be truly reliable for use as a material for ballistic-resistant panels.