Ballistic Impact Dynamic Modeling of Fabric for New Protection Systems

Fabrics are a key component in safety systems ranging from body armor to seat belts and airbags. Estimating the failure under various loading conditions is mostly beyond the state-of-the-art, so we seek a method to give designers more confidence in studying failure limits. Modeling improvements will involve a multi-scale adaptive finite element system using advanced object oriented programming techniques. This permits a consistent modeling approach that transitions from macroscopic multi-layer fabrics to fibril level model of yarns. The adaptivity will be done dynamically based on changing conditions of impact from projectiles, blast or other sources. Testing and constitutive modeling of yarns will be a major part of this effort. The properties of the yarn are critical to failure and the behavior of yarns is complex, given that they are composed of bundles of twisted fibrils that result in unusual properties. Constitutive modeling at the yarn/fibril level is absent from the literature and is a major goal of this research. Using a series of published tests, we will show that the resulting tool is capable of analyzing failure over a wide range of conditions. The final tool will be at a production level to study fabric safety systems.