Influence of surface polymer coating on ballistic impact response of multi-layered fabric composites: Experimental and numerical study

Abstract

Composites based on aramid fibres are widely used to protect people and vehicles from high-velocity impact threats. Currently, quite a lot of attention is paid to methods for increasing the efficiency of such structures without a significant increase in areal density. The article demonstrates the results of experimental and computational studies of two types of multilayer fabric systems based on Twaron® 709. The first system consisted of dry fabric layers, and the second one was based on the fabric layers with polyvinyl acetate (PVA) surface coating. Experimental studies included quasi-static yarn pull-out tests, high-velocity impact tests of specimens without backing support, and tests on a plasticine block to assess the back face bulging. The results of the experiments showed that thin coatings of PVA contributed to a significant pull-out force increase due to polymer connections between the yarns. This effect led to the fact that specimens based on coated fabrics had a ballistic limit twice as much and showed a three-fold decrease in the depth of the dent on plasticine in comparison with dry fabrics. The total increase in surface density did not exceed 6% while maintaining high flexibility of the package. Also, numerical simulations were used to confirm the results of experiments. It was shown that mesoscale yarn-level models allow to predict plasticine indentation depths of the dry and coated multilayer fabric targets.