Characterizing the Interaction Among Bullet, Body Armor, and Human and Surrogate Targets

Abstract

This study used a combined experimental and modeling approach to characterize and quantify the interaction among bullet, body armor, and human surrogate targets during the 10-1000 μs range that is crucial to evaluating the protective effectiveness of body armor against blunt injuries. Ballistic tests incorporating high-speed flash X-ray measurements were performed to acquire the deformations of bullets and body armor samples placed against ballistic clay and gelatin targets with images taken between 10 μs and 1 ms of the initial impact. Finite element models (FEMs) of bullet, armor, and gelatin and clay targets were developed with material parameters selected to best fit model calculations to the test measurements. FEMs of bullet and armor interactions were then assembled with a FEM of a human torso and FEMs of clay and gelatin blocks in the shape of a human torso to examine the effects of target material and geometry on the interaction. Test and simulation results revealed three distinct loading phases during the interaction. In the first phase, the bullet was significantly slowed in about 60 μs as it transferred a major portion of its energy into the body armor. In the second phase, fibers inside the armor were pulled toward the point of impact and kept on absorbing energy until about 100 μs after the initial impact when energy absorption reached its peak. In the third phase, the deformation on the armor's back face continued to grow and energies inside both armor and targets redistributed through wave propagation. The results indicated that armor deformation and energy absorption in the second and third phases were significantly affected by the material properties (density and stiffness) and geometrical characteristics (curvature and gap at the armor-target interface) of the targets. Valid surrogate targets for testing the ballistic resistance of the armor need to account for these factors and produce the same armor deformation and energy absorption as on a human torso until at least about 100 μs (maximum armor energy absorption) or more preferably 300 μs (maximum armor deformation).

Is behind armour blunt trauma a real threat to users of body armour? A systematic review

“…It is broadly accepted that the short duration first peak is related to the initial impact event onto the body armour; the second and later peak is related to the macroscopic deformation of the armour into the body 17 31 32. Both peaks, but particularly the first, are affected by armour construction 25 32 37…”

Reference data on thickness and mechanics of tissue layers and anthropometry of musculoskeletal extremities

“…compared able-bodied subjects to individuals with chronic spinal cord injury to investigate changes in soft tissue stiffness 10 . Finally, this dataset may be used to design clothing, protective equipment 11 , or sockets for artificial limbs 12 .…”

Numerical Simulation of Human Torso Dynamics under Non-penetrating Ballistic Impact on Soft Armor

“…Based on the elastic modulus and tangent modulus, plastic hardening modulus E h can be calculated, as shown in equation (4).…”

“…The results demonstrated that the differences between overpressure values of two models is within 10% under the same impact condition. Shen [4] used a combined experimental and modeling method to characterize the interaction among bullet, body armor, and human surrogate targets. The results exhibited three distinct loading phases during the interaction.…”