Development of 3D auxetic structures using para-aramid and ultra-high molecular weight polyethylene yarns

In recent times, auxetic woven structures gained considerable attention from the researchers due to their excellent impact properties in high-performance areas. Researchers have done much work on the auxetic behavior of the natural and low-performance yarns in two-dimensional structures. Keeping in view the structural application of auxetic structures, in this work, three-dimensional (3D) woven auxetic fabrics were developed on conventional weaving machines with high-performance yarns. Effect of high-performance yarns (Para-aramid and UHMWPE) as the main structure and binding threads on the auxeticity of 3D fabric structures and the impact properties of their corresponding composites were discussed. For this purpose, eight different orthogonal 3D woven structures were produced with para-aramid filament yarn as warp and weft, whereas ultra-high molecular weight polyethylene (UHMWPE) filament yarn was used as a binder. The tensile load was applied to the 3D fabrics to check their auxeticity, and a change in thickness was recorded. The results showed that as the float length of binder yarn and warp yarn increases with the equal and same ratio, the auxeticity also increases. While auxeticity decreases as the difference between the float length of binder yarn and warp yarn increases. The Negative Poisson's Ratio (NPR) of 3D woven fabrics ranged from −0.9 to −2.98. In the second step, these 3D woven fabrics were fabricated into their composites using unsaturated polyester resin, and the hand-layup technique. Their impact strength was measured using the Charpy test method. Auxetic woven composites made of high-performance yarns structures showed impact strength ranging from 55.64 kJ/m2 to 158.46 kJ/m2. HighlightsHigh-performance yarns (Para-aramid and Ultra-high molecular weight polyethylene) were used to create eight 3D woven and composite samples with enhanced auxetic behavior.The result shows that samples having maximum binding yarn float length and fewer intersection points show maximum auxeticity and increased energy absorption.The maximum auxeticity and impact energy absorption obtained was -2.98 and 158.46 kJ/m2, respectively.The current research has applications in protective textiles and bulletproof composite panels.