percent. Although we are still exploring the mechanism responsible for these non-monotonic trends, the results indicate that there exists an optimum combination of carbon concentration and corresponding interaction strength to maximize ballistic performance. 23.5 Next Steps Currently, we are working to expand our computational capabilities in order to simulate larger fibrils. This will allow us to extend our research to include (i) CNT location effects within the fibril and (ii) the effect of defects in the intra-fibril structure. Existing CNT treatment of Kevlar delivers surface coating to the fibril; the high strength non-bonded interaction of Kevlar makes the structure difficult to penetrate. We intend to use molecular dynamics to investigate if there is value in exploring synthesizing techniques that would allow deeper impregnation and more uniform distribution of carbon within the fibril. Additionally, we intend to expand our model to include carbon nanostructure morphology effects. This will allow us to model various carbon allotropes such as graphene and other fullerene structures. Fig. 23.6 MD results depicting fiber failure strain as a function of carbon fraction. Results indicate that a carbon wt% of 0.5 % may lead to the maximum failure strain possible, with decreasing strains realized upon further carbon addition. The different series depict differences realized as a result of increasing the non-bonded interactions between Kevlar and carbon Fig. 23.5 Typical stress strain responses of a Kevlar and a composite fibril 192 C.W. Lomicka et al.
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