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Auxetic woven fabrics made with special geometrical structures have gained the interest of textile scientists in recent years. This paper reports a study on auxetic woven fabric based on a double-directional parallel in-phase zig-zag foldable geometrical structure. Such a fabric has been already produced and investigated for its negative Poisson's ratio effect in two principal directions (weft and warp directions). However, its negative Poisson's ratio effect in biased tensile directions as well as under repeated tensile loading conditions has not been studied yet. Therefore, in this paper, these two limitations are addressed. The auxetic woven fabric was firstly fabricated, and then subjected not only to tensile tests in different tensile directions, including two principle directions and three biased directions, but also to repeated tensile loading. It was found that both the negative Poisson's ratio effect and the resistance to tensile deformation are dependent upon the tensile direction, and the highest negative Poisson's ratio effect and higher resistance to tensile deformation are obtained in two principal directions.

Auxetic woven fabrics made of non-auxetic yarns have gained the interest of textile scientists in recent times. Such fabrics have already been produced and investigated for their negative Poisson's ratio (NPR) effect in two principle directions. However, the NPR effect of these fabrics in different biased tensile directions has not been studied. In particular, the influence of repeated tensile loading on the NPR effect retention ability of fabric has not been explored yet. Therefore, this paper aims to report the NPR effect of auxetic woven fabric in different tensile directions and the influence of repeating tensile cycle tests on its NPR effect retention ability. The auxetic woven fabric is firstly fabricated based on a re-entrant hexagonal geometrical structure by using elastic and non-elastic yarns, and then subjected to single and repeating tensile tests in five different tensile directions, which include two principle directions and three biased directions. It is found that the NPR effect is largely dependent upon the tensile direction and the number of repeating tensile cycles.

This paper reports a study on the geometrical analysis of bi-stretch auxetic woven fabric based on a re-entrant hexagonal geometry. The fabric was first designed and fabricated. Then, the fabric was subjected to tensile tests, and changes in the geometry of the fabric structural unit cell at different tensile strains were observed when stretched either in the warp or weft direction. Based on the observations, a geometrical model was proposed for each stretch direction and used to establish the relationship between Poisson’s ratio and tensile strain. The semi-empirical equations for both stretch directions were finally obtained by fitting geometrical parameters with experimental results. It is expected that the semi-empirical equations obtained in this study could be used in the design and prediction of the auxetic behavior of bi-stretch auxetic woven fabrics made with the same type of materials and geometry, but with different values of geometrical parameters.

Fabrics with zero or negative Poisson’s ratio are referred as auxetic fabrics, which have the unusual property of lateral expansion or zero expansion upon stretch. The use of conventional materials and machinery to produce auxetic fabrics has gained the interest of researchers in recent years. However, this approach is limited to knitted fabrics only. The development of auxetic fabric using conventional yarns and weaving technology is a research area that is still unaddressed. This paper reports a study on the development of a novel class of stretchable auxetic woven fabrics by using conventional yarns and weaving machinery. The phenomenon of differential shrinkage was successfully employed to realize auxetic geometries capable of inducing auxetic behavior in woven fabrics, and a series of auxetic woven fabrics were fabricated with elastic and non-elastic yarns and a dobby machine. The uni-axial tensile tests showed that auxetic woven fabrics developed exhibited zero or negative Poisson’s ratio over a wide range of longitudinal strain.

Textile structures have become quite popular as reinforcement materials in composite laminates due to their high impact-damage tolerance and energy absorption ability. The impact performance of textile composites is not only affected by the type of fiber/ matrix but also by the fabric structure used as reinforcement. The aim of this study was to compare the mechanical and ballistic performance of composite laminates reinforced with single-layer and double-layer interlocked woven fabrics. Kevlar V R 229 multifilament yarn was used for preparation of all the fabric structures and epoxy resin was used as the matrix system. The composites were produced using a hand lay-up method, followed by compression molding. The mechanical and ballistic performance of composites reinforced with single-layer and double-layer interlocked woven fabrics was investigated in this study. The energy absorption and mechanical failure behavior of composites during the impact event were found to be strongly affected by the weave design of the reinforcement. The composites reinforced with doublelayer interlocked woven fabrics were found to perform better than those comprising single-layer fabrics in terms of impact energy absorption and mechanical failure. POLYM. COMPOS., 00:000–000, 2013. V C 2013 Society of Plastics Engineers

Auxetic textiles are materials which possess negative Poisson’s ratio, this implies that in contrast to conventional textile materials if they are stretched in longitudinal direction, a marginal expansion will results in transversal direction. Auxetic textile materials have become a point of focus for many researchers in recent past years. This paper reviews the achievements in the area of auxetic textile materials including fibres, yarns, fabrics and textile reinforcements for composite applications. It is aimed that this review will be helpful for future advancement in the area of auxetic textile materials.