Application of the model of leaf and glaskin to estimating the 3D elastic properties of knitted-fabric-reinforced composites

Abstract

This paper presents an analytical procedure for estimating the three-dimensional (3D) elastic properties of a plain-weft-knitted-fabric-reinforced polymer-composite material. The composite material under study is assumed to have mainly reinforcement-fiber yarns and a polymer matrix. The model of Leaf and Glaskin for plain-weft-knitted fabrics is used to determine the geometrical description of the yarn in the composite. The fabric in a representative volume is considered as a series of yarn segments, which are assumed to be made of transversely isotropic unidirectional fiber-reinforced composites. A new micromechanical model is proposed to predict the elastic constants of the unidirectional-fiber-reinforced composites. The compliance/stiffness matrix of each yarn segment is then transformed from the material co-ordinate system to the global coordinate system. In contrast to the commonly used Voigt and Reuss averaging methods, a volume-averaging scheme is developed to obtain the over-all compliance/stiffness matrix of the knitted fabric composites. The predicted results are found to be in good agreement with experimental data. The effects of the fiber content and other parameters of the knitted fabric on the elastic properties of the composite material are described. © Textile Institute.