Varying the performance of helical auxetic yarns by altering component properties and geometry
Reason for embargo
This paper presents a systematic study of the helical auxetic yarn (HAY) via careful in-house fabrication and characterisation of a wide range of polymeric fibres and yarns. It provides a better understanding of the auxetic behaviour of the HAY in order to tailor their properties for specific applications. The study focused on three parameters: component moduli, the core/wrap diameter ratio and the initial wrap angle. The results show that a larger difference in component moduli, a higher core/wrap diameter ratio and a lower initial wrap angle can produce a larger maximum negative Poisson's ratio value and thereby a better auxetic performance for HAYs. All three parameters could be carefully utilised when in combination to achieve the required auxetic behaviour of HAYs. Moreover, the instantaneous true Poisson's ratio analysis accurately presents the instantaneous behaviour of highly strain dependent HAYs.
This work is supported by the UK Engineering and Physical Science Research Council (EPSRC Grant No. EP/J004553/1). The authors would like also to acknowledge their colleagues Dave Baker and Yat-Tarng Shyng for technical support.
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.
Vol. 140, pp. 369 - 377