Negative Poisson’s ratio weft knitted continuous filament PP fabric/epoxy resin composites with different loop lengths under impact loading

Auxetic fabrics have numerous applications, mainly in safety armoring such as bullet protection vests, and lots of industrial utilities including aerospace. The Negative Poisson’s Ratio (NPR) primarily based on Weft knitted (auxetic) fabric has been examined in this research. The Negative Poisson’s Ratio weft knitted material has been prepared in a form of composite panel by knitting continuous polypropylene filament yarn using weft knitting technique on a flat knitting machine (Passap Deumatic 80), as 1 × 1 rib structure (fisherman’s rib) with three combination of loop lengths (LL3, LL4, and LL5). Investigations were carried out for the various loop lengths at the Negative Poisson’s Ratio (NPR) with inside the wales and courses directions. The composite panels were manufactured using Risen Transfer Molding (RTM) process. The load-displacement test curves obtained signify the failure mechanisms for the different loop lengths. Impact parameters have been evaluated comparing the different loop lengths of the composites. Failure modes have been examined carefully and sighted under optical microscope. The effects evaluated showed that the LL3 have the best highest peak of load, and the LL5 have the lowest decline of load curve, maximum displacement and minimal power absorption. The failure mode revealed matrix cracking, and surface buckling.