A Study of Material and Architectural Effects on the Impact Response of 2D and 3D Dry Textile Composites using LS-DYNA

High strength 2D fabrics and 3D textile composites comprised of materials such as KevlarTM, VectranTM, ZylonTM, and S2-Glass® find applications in protective systems such as personnel armor, spall liners, and turbine fragment containment. Various parameters can significantly affect the response of these fabrics under high rate impact including yarn/tow geometry (cross section), yarn/tow material (modulus, strength), and architecture (undulations and span). However these are just a few of the many other parameters such as projectile characteristics, boundary conditions, number of layers and orientations, weaving degradations, and so forth. Many of these parameters are inter-related and unfortunately this makes a comprehensive study very complex. Therefore, a set of key parameters have been identified for an initial exploratory numerical investigation. These include, on the material front: yarn/tow axial modulus, strength, frictional coefficient; and on the architectural front: yarn/tow cross section shape, size, span, and angle of inclination of through-thickness stitching or Z-tows. This study provides interesting initial insight into the role of through thickness tows on the overall impact resistance and energy dissipation capabilities for which these high strength fabrics were designed for. 3D fabrics with varying Z-tow architectures are compared against each other as well as against 2D fabrics without through thickness stitching. A special in-house preprocessor DYNAFAB is used to automatically generate the entire textile composite mesh. The user inputs basic parameters describing the desired yarn/tow geometry, architecture, and mesh density. The output is a LS-DYNA keyword input-file ready to use in the simulation. The geometry and undulations in the FE model closely represents the actual micrographs of the textile composite leading to a realistic representation of the architecture.