Investigating the influence of the core material on the mechanical performance of a nitinol wire wrapped helical auxetic yarn

Helical Auxetic Yarns (HAYs) can be used in a variety of applications from healthcare to blast and impact resistance. This work focuses on the effect use different core materials (e.g. rubber, polyurethane, polytetrafluoroethylene/teflon, polypropylene, polyetheretherketone, polycarbonate, acetal) with nitinol wire wrap component maximum Negative Poisson Ratio (NPR) produced thus auxetic performance (HAYs). From analytical model, it was found that an acetal largest NPR when compared other six materials. The trend obtained experimental tensile tests (validation) correlated closely theoretical predictions as axial strain increased. method presented at average 0.148 which close 0.155 predicted by theory. However, significantly lower than model.