Mechanical properties of a novel tri-component high stiff auxetic reinforced composite structure

Abstract

Helical Auxetic Yarn (HAY) possesses negative Poisson’s ratio. These yarns can be successfully used as reinforcing elements in composite materials. This paper proposes a novel tri-component helical auxetic structure capable of enhancing the initial modulus of HAY. The novel structure comprises a high modulus thin secondary core II positioned along the first low modulus thick primary core I. An additional stiff strand wraps the cores I and II. Using statistical techniques, evaluation of the secant modulus and not Young’s modulus was carried out and validated. The resultant structure was found to possess a relatively high elastic modulus in the range of 11–15 GPa. The structure exhibited an auxetic phenomenon of −62. It was revealed that such high stiffness auxetic yarn could successfully be utilized as reinforcing elements in high stiffness cost-effective auxetic composite structures.