Heterogeneous lightweight configuration for protection against 7.62 × 39 mm bullet impact

Abstract

Configuration of a heterogeneous lightweight material is investigated numerically and experimentally, for protection against 7.62 × 39 mm mild steel core bullet impact. The configuration consists of alumina (Al2O3) tile followed by fiber glass and polyurethane foam, all covered with kev-epoxy layer. Numerical simulations were performed using ANSYS AUTODYN. The 10-mm thick alumina completely disrupts the impacting bullet through blunting and erosion. The fiber glass and polyurethane foam disperse and absorb the propagation of shock wave, respectively. The kev-epoxy cladding seizes any scattering of brittle alumina fragments. The average impact velocity of the bullet was measured to be 710 m/s using high-speed camera. A 10-mm depth of depression spread over a wider area of 3.92 sq in of torso was recorded in blunt force trauma test, which was well within the European, German, and British standards that allow a 20–25 mm backface signature. Due to these characteristics it can be employed as body armor, vehicle armor, and for the safety and security of other critical infrastructures against this bullet and fragment impact. The residual mushroom-shaped bullet and its length of 9.3 mm in numerical simulation is in close agreement with the measured value of the 8.0 mm recovered bullet size and shape.

Numerical modelling study of a modified sandbag system for ballistic protection

“…Projectile velocity of 850m/s is equivalent to the velocity of a 12mm spherical fragment from a 155mm artillery shell at 11.7m (based on Gurney equations -Appendix A). The thickness of the plates (15 and 25mm) was selected based on previous work with composite armour systems [12,33,34]. The location of the plate was decided based on the maximum penetration of the projectile in the sand and the size of the compacted section of sand ahead of that point.…”

“…Furthermore, the barriers still face the risk of being displaced when subjected to blast which in turn increases the risk of collateral damage to personnel [11]. In addition to this, there have been multiple studies done to show that geoparticles larger than sand are more effective at responding to a ballistic threat [12][13][14]. Moreover, these kinds of barriers are mainly suited for military applications primarily due to their size and the space required for their setup.…”

Experimental investigations of the response of a portable container to blast, fragmentation, and thermal effects of energetic materials detonation

“…The Johnson-Cook failure model (Johnson and Holmquist, 1994) shown in equation (8) was used along with the strength model for casing material (AISI-1006). The material properties of steel 1006 were used from Autodyn library (Ahmed et al, 2019; Lee et al, 1968).…”