Development of Sandwich Composites from Natural Materials for Bullet Proofing

Abstract

Ballistic protective materials have been used in the past are replaced with synthetic polymer composites due to their strength to weight ratio. Nowadays, these synthetic materials are being replaced by natural fiber reinforced composites due to the cost and environmental issues. The present investigation relates to the development of natural sandwich/laminated composite material interlock blocks for bullet arresting. Bullet arresting capacity depends on energy absorption. The energy absorption of the material could be increased by different ways. Among which sandwich form of the composite is one of the effective ways of improving the energy absorption capability of PMCs. This study was undertaken to explore the use of natural materials such as Jute epoxy fly ash composite (JEFC), Jute-epoxy fly ash rubber (JEFRC) sandwich composite for ballistic energy absorption. Prior to FE analysis, mechanical characterization of three varieties of jute composites were carried out namely Tossa jute single woven composite (TSWC), White jute single woven composite (WSWC), White jute double woven composite (WDWC) among all Tossa jute single woven composite (TSWC) revealed better mechanical properties. Hence for further analysis, Tossa jute single woven epoxy fly ash composite nothing but Jute epoxy fly ash composite (JEFC) is only used for ballistic FE simulation and as well as for ballistic impact testing of composite plates, blocks and interlock blocks. Finite Element analysis of these plates was carried out for thicknesses (5, 10, 15 mm). JEFC plates and JEFRC sandwiches with the same thickness (15 mm) were fabricated and tested to measure residual velocity and energy absorbed. Among JEFC and JEFRC, JEFRC showed better ballistic performance hence further analysis is carried out on jute-epoxy-fly ash natural rubber sandwich block composite (JEFRC), at different thicknesses of the target plate (50, 75, 100, 150 mm) and three velocities of the projectile (150, 250, 350 m/s). Ballistic parameters were evaluated using commercial FE software. Further same thickness and same configuration sandwich blocks were produced using compression molding machine; these prepared samples were subjected to ballistic impact test by impacting the projectile. From FE analysis and ballistic test, it is confirmed that at about 75 mm thickness the sandwich blockswere capable of arresting the bullet. Further interlock sandwich blocks were produced and tested for ballistic impact, which arrested the bullet half of its thickness. Hence such sandwich interlock blocks are produced to prototype for arresting bullet up to velocity 350 m/s. Fracture behavior is analyzed using SEM.