High velocity impact properties characterization of nano-phased bi-layered body armor

It has been already established by different investigators that addition of nano-reinforcements to plastics and fibers further enhances the mechanical and thermal properties of these materials. In this investigation, we have tested a bi-layer composite armor made of a ceramic layer and a nano-reinforcement infused epoxy layer. Our objective is to determine whether the infusion of nano-reinforcements in an epoxy layer enhances the ballistic properties of this bi-layer armor system. This bi-layered armor which was made of an alumina layer and a nano-infused epoxy layer was tested by a Fragment Simulating Projectile (FSP) method. Silica nanoparticles and multi walled carbon nanotubes (MWCNT) with a loading range of 0-1wt% were used for this purpose. Armors having the same thickness but made of only a single pure ceramic layer and a bi-layer composite made of a ceramic layer and a neat epoxy layer were also tested for comparison purposes. A gas gun with high velocity projectile was used to perform the experiment. A striking velocity of about 400m/s was used to hit the target armor plate. The striking velocity of the projectile was obtained by maintaining a breach end pressure of helium gas in the gas gun at about 500 psi. The striking velocity was chosen at a level which was well above the ballistic limits of the armor materials. A finite element analysis was also performed to evaluate the ballistic properties of the composite armor and to compare those with the experimental data. Numerical and experimental results for the residual velocity of the piercing bullets were found to be in good agreement. Details of the experimental and numerical data are presented in this paper.