Auxetic Yarn Made with Circular Braiding Technology

TLDR

This paper introduces a circular‑braided auxetic yarn designed to eliminate yarn slippage in conventional helical auxetic structures. The yarns were fabricated on a vertical circular braiding machine with 16 carries by varying stiff yarn number and arrangement, elastic yarn diameter, and core yarn, then tested under single and repeated tensile loading. The new auxetic yarn eliminates slippage, activates earlier, and exhibits a larger negative Poisson’s ratio, with its performance modulated by stiff yarn number, arrangement, core yarn, and elastic yarn diameter, and can be produced at scale using standard braiding techniques.

Abstract

This paper reports a new type of auxetic yarn made with circular braiding technology to overcome the yarn slippage problem in the conventional helical auxetic yarn structure. Various auxetic yarn structures are firstly produced on a vertical circular braiding machine with 16 yarn carries by changing the number and arrangement of stiff yarn as well as diameter of elastic yarn and core yarn, and then tested under single and repeating tensile conditions. The results show that not only yarn slippage problem could be overcome in the newly developed auxetic yarn structure, but also an early activation and a higher magnitude of negative Poisson's ratio could be achieved. The results also show that all structural parameters including stiff yarn number and arrangement, core yarn, and elastic yarn diameter have an influence on the auxetic effect of the novel yarn structure. Since the new auxetic yarn is produced by using standard braiding manufacturing technique and conventional non‐auxetic yarns, there are few technological barriers for its large‐scale manufacture for practical application.