Design and characterization of 3D folded weft-knitted auxetic fabrics based on aramid yarns with different rib configurations and loop densities

This study investigates the auxetic behavior of three-dimensional (3D) folded weft-knitted fabrics produced from aramid yarns. Although folded auxetic geometries have been previously reported, a systematic understanding of the influence of rib configuration and loop density on auxetic performance remains limited. In this work, a series of foldable 3D auxetic structures were engineered based on rib configurations of 6×6, 8×8, and 10×10, with variations in loop density on the face and reverse sides (slack, medium, and tight) to examine their influence on NPR behavior. The effects of rib width and fabric density on the negative Poisson’s ratio (NPR) were experimentally evaluated. The results revealed that both the zigzag rib geometry and the differential loop densities significantly affected the auxetic performance. In particular, an increase in rib structure size combined with a reduction in stitch density resulted in a pronounced enhancement of the NPR effect. The correlation analysis confirms that auxetic behavior in weft-knitted fabrics is primarily governed by structural looseness and geometric configuration. Thickness emerges as the most influential parameter, showing the strongest correlation with negative Poisson’s ratio. The study provides a comprehensive structure property relationship, offering practical guidelines for the design of high-performance auxetic textiles.