Fiber-Level Modeling of Dynamic Strength of Kevlar (registered trademark) KM2 Ballistic Fabric
ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD SURVIVABILITY MATERIALS BRANCH
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In recent years, modeling of the high-performance ballistic fabric has gradually shifted from the continuum and yarn length scales to the sub-yarn length scale which enabled establishment of the relationships between the fabric penetration resistance and various fiber-level phenomena such as fiber-fiber friction, fiber twist, transverse properties of the fibers, and the stochastic nature of fiber strength. In general, these sub-yarn modeling schemes involve special numerical techniques e.g., digital-element method and customized computational codes. This status of the sub-yarn fabric-modeling methods and tools makes them not readily available to wider academic and industrial research communities. In the present work, an attempt is made to use conventional finite-element methods and tools in order to carry out sub-yarn numerical analysis of the penetration resistance of Kevlar KM2 ballistic fabric. The goal was to demonstrate that results could be obtained which are comparable to their digital-element method based counterparts. Specifically, a series of transient nonlinear dynamics finite-element analyses was carried out in order to investigate the role of the following two important sub-yarn phenomena on the penetration resistance of Kevlar KM2 fabric a fiber transverse properties including nonlinear elastic and plastic response and b fiber-fiber friction within the context of stochastically distributed fiber axial strength. It is generally found that the results obtained are consistent with their digital-element method-based counterparts.