Woven Fabrics Made of Auxetic Plied Yarns

Abstract

Auxetic plied yarns are specially constructed with two types of single yarns of different sizes and moduli. This paper investigates how to use these types of yarns to produce woven fabrics with auxetic effects. Four-ply auxetic yarns were first incorporated into a series of woven fabrics with different design parameters to study their auxetic behavior and percent open area during extension. Effects of auxetic plied yarn arrangement, single component yarn properties, weft yarn type, and weave structure were then evaluated. Additional double helical yarn (DHY) and 6-ply auxetic yarn woven fabrics were also made for comparison. The results show that the alternative arrangement of S-and Z-twisted 4-ply auxetic yarns in a woven fabric can generate a higher negative Poisson's ratio (NPR) of the fabric. While the higher single stiff yarn modulus of auxetic yarn can result in greater NPR behavior, finer soft auxetic yarn does not necessarily generate such an effect. Weft yarns with low modulus and short float over the 4-ply auxetic yarns in fabric structure are favorable for producing high NPR behavior. The weft cover factor greatly affects the variation of the percent open area of the 4-ply auxetic yarn fabrics during extension. When different kinds of helical auxetic yarns (HAYs) are made into fabrics, the fabric made of DHY does not have the highest NPR effect but it has the highest percent open area, which increases with increasing tensile strain.

Auxetic Yarn: Fundamentals, Influencing Parameters, Application Areas and Challenges

“…Ng et al produced 6-ply auxetic yarns and reported on their auxetic behaviour as well. However, they compared the NPR among the DHY, the 4-ply and the 6-ply auxetic yarn (Figure 7) and concluded that the 4-ply auxetic yarn has a greater NPR result than the other two auxetic yarns [2]. Compared to the DHY which has a filament helically wrapped around a barely twisted filament and is unstable, the auxetic plied yarn is more robust.…”

“…The behaviour of the material under deformation in this case is dictated by Poisson's ratio, which is one of the fundamental mechanical properties of materials [1]. Poisson's ratio is defined as the ratio of lateral contractile strain to longitudinal tensile strain [2]. Positive value of Poisson's ratio is found in all common materials, which means they contract transversely under uniaxial extension and extend laterally when compressed in one direction [1].…”

“…They observed better auxeticity when the composite is produced from auxetic textiles instead of conventional textiles [18,19]. Similarly, NPR characteristics of auxetic yarns can be transferred to the fabric although yarns are incorporated into fabric conventionally [2,4]. Furthermore, composites made of auxetic materials are designed for crash helmets and sports apparels, ropes, filtration, and shock absorbing materials [3].…”

“…Auxetic yarns may be used to make fabrics without the need to learn new fabrication techniques [22]. The NPR effect can be achieved by simply weaving or knitting patterns to fabricate auxetic textiles by utilizing auxetic yarns [2]. Auxetic woven fabrics composed of auxetic yarns in both weft and warp directions have been implemented and tested [2,23].…”

“…The NPR effect can be achieved by simply weaving or knitting patterns to fabricate auxetic textiles by utilizing auxetic yarns [2]. Auxetic woven fabrics composed of auxetic yarns in both weft and warp directions have been implemented and tested [2,23]. The most widely utilized components for engineering auxetic yarns are high modulus filament combined with an elastic core element [23].…”