Page 1 of 10 A Review on Auxetic Textile Structures, Their Mechanism and Properties Andrews Boakye, Yuping Chang, Rafiu King Raji and Pibo Ma* Jiangnan University, China Introduction Figure 1: Effect when force is applied to both conventional and auxetic materials. Almost all materials possess a positive Poisson’s ratio, in the sense that they shrink when stretched and expand when compress. These are basically referred to as conventional materials and their Poisson’s ratio (v) value ranges from 0.0 to 0.5 [1]. Unlike the conventional, auxetic materials exhibit a negative Poisson’s ratio (NPR), which laterally expand when stretched and laterally contract when compressed [2]. Knowledge about auxetics can be trace as far back in the 1800s where Voigt et.al had already discovered the NPR in some materials but didn’t draw much attention to it [3]. Later in 1987 a man by name Lakes reported an auxetic foam structure that could be produced easily by tri-compression and heating which were considered to be a man-made process [4]. Developments on auxetic materials thereafter have never ceased. Scientist and researchers have comprehensively, dived into knowing every bit about auxetics, right from its structure and deformational behavior as compared to conventional materials, to how it could be artificially produced and its application thereafter. Figure 1 shows the effect that occurs when a force is applied to both conventional and auxetic material. Poisson’s ratio basically describes the relative change in the natural dimension of an object when a load is applied in a longitudinal direction or other way [5]. Mathematically, it could be expressed as; Poisson’s ratio () y x v ε ε =− Where y ε and x ε are transverse strain and axial strain respectively. Auxetic mechanical metamaterials according to [6] are engineered systems that exhibit the unusual macroscopic property of a negative Poisson’s ratio due to sub-unit structure rather than chemical composition. The auxetic of a material is dependent on its geometrical structure and the material’s system and deformation *Corresponding author: Pibo Ma, Engineering Research Center for Knitting Technology, Ministry of Education, College of Textile and Clothing, Jiangnan University, China. Received Date: November 27, 2018 Published Date: January 30, 2019 ISSN: 2641-192X DOI: 10.33552/JTSFT.2019.02.000526 Journal of Textile Science & Fashion Technology Review Article Copyright © All rights are reserved by Pibo Ma This work is licensed under Creative Commons Attribution 4.0 License JTSFT.MS.ID.000526. Abstract Materials that possess a negative Poisson’s ration are classified to be auxetic textile materials. As compared to conventional materials, they exhibit a counter-intuitive quality which enables them to expand longitudinally when stretched and contract laterally when compressed. This counter- intuitive effect occurs as a result of the structural deformation of these auxetic textile materials when they are subjected to tension. This paper considers the current structures of auxetic textile materials, more importantly their deformational mechanism, properties and some general applications. Keywords: Auxetic textile materials, Counter-intuitive, Negative poisson’s ratio (NPR)