Multi-scale Testing Techniques for Carbon Nanotube Augmented Kevlar

We explore a method for improving the ballistic performance of Kevlar by augmentation with multi-walled carbon nanotubes (MWNTs). When developing new and improved soft armor, ballistic testing is expensive while the crude data obtained provide limited insight into those mechanisms which enable smart design. Therefore, we tested and modeled yarns and fabrics at various length scales to optimize our synthesis process and understand mechanisms contributing to ballistic performance, thus necessitating ballistic testing of only the potential best performers. Tensile testing of treated yarns was performed to measure the strength and modulus, both linked to ballistic performance, and to evaluate the relative success in infiltrating the Kevlar with MWNTs. Yarn friction and yarn pull-out tests were performed to measure the static and kinetic yarn-to-yarn interactions (friction), also critical to performance during a ballistic event. Example results from mechanical testing over multiple length scales, including ballistic testing, are reported. Finite element modeling was also used to study the effects of the fabric material properties and friction on ballistic performance. Simulation results were correlated with experimental data and used to guide materials optimization.