The formation and performance of auxetic textiles. Part II: Geometry and structural properties

Abstract

Some exceptional materials become fatter when stretched and are described as auxetics or having negative Poisson's ratio. Auxetic textiles belong to this class of extraordinary materials that are increasingly attaining some prominence in many applications of technical textiles. We have sustained the efforts to fabricate auxetic fabric structures based on non-auxetic yarns. The focus is to combine our knowledge of geometry and fabric structural characteristics to engineer auxetic textiles and to determine the properties of such auxetic textile fabrics. To realize our objective, we designed and investigated hexagonal knit structures as auxetic textiles offering optimum performance. The factors that influence Poisson's ratio are identified as yarn type, number of chain courses and strain level. Also, a method has been developed for quantifying the geometrical structural unit cell of the auxetic structure based on measured parameters, namely a1, a2, b1, b2, h and c, as detailed in this paper. © 2011 The Textile Institute.