Effect of matrix on ballistic performance of soft body armor

We analyze three-dimensional (3-D) deformations of soft body armor in the form of a clamped rectangular plate impacted at normal incidence by a projectile. Results have been computed by the finite element method, using the commercial software LSDYNA, for the armor with and without a matrix, and in the former case with either perfect or no bonding between the matrix and the yarn. Also, two impact speeds and two polymers, one stiffer than the other, have been considered. Significant contributions of the work include studying 3-D elastoplastic deformations, and delineating the effect of the matrix on the ballistic performance of the armor. It is found that the matrix reduces the maximum deflection of the armor, increases the size of the deformed area, and enhances the reduction in the kinetic energy of the projectile. However, the size of the deformed area is not a good indicator of the energy absorbed during impact. These results are useful for armor designers since the reduction in the maximum deflection should reduce the intensity of injuries to persons wearing the armor. On the other hand the larger deformed area of the armor can increase the possibility of injuries.