Comparative Geometrical Analysis of In Situ Mechanical Performance of 2-D Woven In-Plane Auxetic Structures

Recently, the production of auxetic textiles using conventional yarns and equipment has captured the attention of researchers. Yet only uni-stretch 2-D woven auxetic structures and auxetic knitted textiles have been produced using conventional yarns. This paper reports a comparative analysis of auxetic and mechanical performance (tensile strength, tear strength, and stretch and growth %) performance of auxetic foldable and auxetic honeycomb (AHC) structures using common elastic and nonelastic yarns and conventional weaving technologies. For this purpose, five different auxetic weave designs including & alpha;-vertical pointed twill (S1), 13 vertical pointed twill (S2), & alpha;-horizontal pointed twill (S3), 13-horizontal pointed twill (S4), and honeycomb structure (S5) were selected, and their corresponding woven fabrics were developed with equal thread density at the weaving stage. Auxeticity of woven structures was measured in both the warp and weft directions. The results showed that when the developed fabrics were stretched along the warp and weft directions, the foldable geometry showed -1 and -0.07 maximum negative Poisson's ratio (NPR), respectively. Although the AHC structure showed maximum NPR -0.94 and -0.21 along warp and weft directions, respectively. AHC showed better mechanical performance as compared with foldable geometry and has higher dimensional stability. AHC structure showed the highest tensile strength as compared with the others. S3, S4, and S5 remained untorn along the warp direction because these have longer float lengths that produce a bunch having a greater number of yarns, whereas S1 and S2 showed tear strength of 47 and 43.2 N, respectively. In the weft direction, only S1 remained untorn, whereas the other four samples showed the tear strength value.

Automated summary

This paper compares the auxetic and mechanical performance of foldable and honeycomb structures using different yarns and weaving technologies. The results show that the honeycomb structure has better mechanical performance and higher dimensional stability.