Variation of Poisson’s ratio of fabrics woven with helical composite auxetic weft yarns in relation to fabric structural parameters

Auxetic textiles are defined as textiles with negative Poisson’s ratio. These textiles possess unique properties that render them suitable for special applications. This work aims to investigate the effect of fabric structural parameters such as thread densities, weave design and warp yarn count. Thus, 30 fabric samples were woven at 3 weft and 2 warp densities, respectively. Two warp counts and three weave designs of plain, basket 3/3 and weft-backed satin 6 were used. The samples were uniaxially loaded in weft direction and dimensional changes at various strains levels were evaluated. The evaluation was carried out using the image processing technique based on MATLAB software. The weft yarns used were found to exhibit auxetic behavior at the whole spectrum of the strain level used. The least weft yarn Poisson’s ratio was found to be −0.9. It was established that in general the fabric samples exhibit auxetic effect within the stated range of strain. Additionally, it was concluded that while fabric thread densities together with warp count influence the minimum fabric Poisson's ratio, auxetic behavior of the samples is not dependent on weave design alone. Rather, it was illustrated that the combined effect of weave design in association with stated structural parameters on auxetic feature cannot be ignored.