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 of the use of different core materials (e.g. rubber, polyurethane, polytetrafluoroethylene/teflon, polypropylene, polyetheretherketone, polycarbonate, acetal) with a nitinol wire wrap component on the maximum Negative Poisson Ratio (NPR) produced, and therefore the auxetic performance of Helical Auxetic Yarns (HAYs). From the analytical model, it was found that an acetal core produced the largest NPR when compared to the other six materials. The trend obtained from the experimental tensile tests (validation) correlated closely with the theoretical predictions of the NPR as axial strain was increased. The experimental method presented a maximum NPR at an average axial strain of 0.148, which was close to the strain of 0.155 predicted by theory. However, the maximum experimental NPR was significantly lower than that predicted by the analytical model.
FAISAL, N.H., FOWLIE, A., CONNELL, J., MACKENZIE, S., NOBLE, R. and PRATHURU, A.K. 2022. Investigating the influence of the core material on the mechanical performance of a nitinol wire wrapped helical auxetic yarn. Journal of strain analysis for engineering design [online], 57(5), pages 377-391. Available from: https://doi.org/10.1177/03093247211027085