Impact Resistance of Layered Aramid Fabric: A Numerical Study on Projectile-Induced Damage.

The aim of this work is to comparatively analyze, using numerical simulation, the impact behavior of aramid fabric. A layered panel was impacted by two projectiles specific to the NIJ protection level HG1. The protection level in this study is based on NIJ Standard 0123.00. This standard is used to establish protection levels. The two projectiles specific to the NIJ HG1 protection level are 9 mm Luger and .357 Mag FMJ. Law enforcement personnel use body armor designed to protect the torso. With the help of numerical simulation, the mechanisms of destruction of the aramid fabric on impact are identified. The protection performance is analyzed as a function of the influence of the number of layers and the projectile velocity variation. The fabric is modeled at the yarn level, with each yarn consisting of hundreds or even thousands of fibers. Simulations are performed at the yarn level, since fiber-level modeling is difficult to implement due to high computational resource requirements. The material properties for the yarn, as well as for the projectiles, are selected from the literature. The results show that only the 20-layer fabric panel impacted by the 9 mm Luger FMJ RN 9 mm FMJ RN projectile at 398 m/s meets the protection requirements of the NIJ standard (NIJ HG1 protection level). In contrast, panels impacted at 436 m/s, or those with fewer layers, show rapid stress wave propagation, severe deformation, and complete perforation, indicating insufficient energy dissipation. This study highlights the critical role of impact velocity, projectile geometry, and number of layers in determining ballistic resistance. These findings contribute to the development of more effective ballistic protective equipment, highlighting the need for optimized layer configurations and improved material properties to meet NIJ standards under different impact conditions.