Investigation of auxetic woven fabric structural parameters

Deformation under tensile loading is one of the methods that can be used to determine the physical performance behaviors of fabrics. Conventional fabric structures have a positive Poisson ratio (PR) because they show contraction in the transverse direction under longitudinal elongation. Auxetic structures have a negative Poisson ratio (NPR) and they expand in the transverse direction under elongation and contract as they are compressed. Auxetic structures show improved performance properties (increased mechanical properties, variable permeability, improved energy and acoustic absorption properties, etc.). By designing woven fabric structures with auxetic properties, it would be possible to gain many functional features to the structure in one step compared to conventional fabric structures. In terms of usage area, the use of woven fabric structures with auxetic performance could be preferred in areas that require high performance especially in technical textiles and in appropriate usage areas in terms of increased comfort properties. In this study, the effects of various fabric structural parameters that could gave auxetic effect to the woven fabric structure were investigated in order to obtain woven fabric structures with auxetic properties. The effects of yarn with different structural properties (braid yarn, helical ply yarn (HPY) and monofilament latex) and weave pattern (the effect of yarn intersection and floating amount in the weave structure) on the auxetic performances of the fabric were investigated. From the results obtained within the scope of the experimental study, it was observed that an NPR effect could generally be obtained in the warp direction, in fabrics woven by using bulky yarn structures (such as braid and helical plied yarn) and monofilament latex structure component as weft yarn. It was observed that the NPR effect obtained from the fabrics was affected by the structural properties of the yarns (the number of filaments forming the yarns, the thickness, bulkiness, softness/hardness properties of the yarns) and the weave structure of the fabric (the number of intersection and floating of the yarns in the fabric). This study was supported by The Scientific and Technological Research Council of Turkey (TUBITAK): Project No.119M358. Key words: Auxetic effect, woven fabric constructional parameters