Influence of re-entrant hexagonal structure and helical auxetic yarn on the tensile and auxetic behavior of parametric fabrics

This paper focuses on systematically analyzing the influence of macro fabric structure and yarn architecture on the mechanical and auxetic performance of parametric auxetic fabrics. Re-entrant hexagonal (REH) and helical auxetic yarn (HAY) were adopted as a macro fabric structure and weft yarn to produce three kinds of auxetic fabrics: REH fabric with HAY as weft yarn (REH-HAY); REH fabric with elastic yarn as weft yarn (REH-1, REH-2, REH-3); and plain fabric with HAY as weft yarn (NREH-HAY). By controlling the existence of the HAY and REH structure, the influence of the REH structure and HAY on the mechanical and auxetic properties was thoroughly analyzed. It is demonstrated that both the REH macrostructure and HAY micro configuration can contribute to the performance of the auxetic fabric. Specifically, in the presence of the REH structure and HAY, the auxeticity was found to a 77% increase compared with NREH-HAY and the breaking strain and load rises by about 37.50% and 90.42%, respectively. Notably, the variation of the polyurethane (PU) weft yarn per unit length influenced the tensile and auxetic performance to a lesser extent, while by changing PU to HAY, a significant increase of negative Poisson's ratio value from -1.155 to -1.492 was noticed without greatly jeopardizing the stretchability. Furthermore, the cyclic tensile results demonstrate the stability and elasticity of the fabric. The comparative analysis can give guidance to optimize fabric design and inspire the innovative design of the auxetic textiles, all of which will pave the way for a quantitative and optimizing design for auxetic textiles.