Kinetic Dissipation in Ballistic Tests of Soft Body Armors

The objective of this study was to assess the amount of energy transferred to the backing material of oil-based clay (i.e. kinetic dissipation) in ballistic tests of soft body armor panels. To determine the relationship between penetration depth (or dent volume) and impact velocity (or energy), weight dropping test with a series of steel spheres was carried out at low impact velocities, and direct shooting with a 5.56 mm NATO fragment simulating projectile (FSP) was carried out at high impact velocities. At high and low impact velocities, the volume of the dent made in the oil-based clay was proportional to the velocity of the impactor. The change in dent volume per the change in impact velocity was found to be proportional to the 1.5th power of the mass of the impactor, while the energy absorption per unit dent volume increased linearly with the impact velocity. The relationship between trauma depth (or dent volume) and kinetic dissipation of a soft body armor panel subjected to a 9 mm bullet at 436 m/s is presented, where the trauma diameter approached that of a 1.043 kg steel ball.