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

This paper presents an analytical procedure for estimating the three-dimens ional (3D) elastic properties of a plain-weft-knitted-fabric-reinforced pol ymer-composite material. The composite material under study is assumed to h ave mainly reinforcement-fiber yarns and a polymer matrix. The model of Lea f and Glaskin for plain-weft-knitted fabrics is used to determine the geome trical description of the yam in the composite. The fabric in a representat ive volume is considered as a series of yam segments, which are assumed to be made of transversely isotropic unidirectional fiber-reinforced composite s. A. new micromechanical model is proposed to predict the elastic constant s of the unidirectional-fiber-reinforced composites. The compliance/stiffne ss matrix of each yam segment is then transformed from the material co-ordi nate system to the global coordinate system. In contrast to the commonly us ed Voigt and Reuss averaging methods, a volume-averaging scheme is develope d to obtain the over-all compliance/stiffness matrix of the knitted-fabric composites. The predicted results are found to be is good agreement with ex perimental data. The effects of the fiber content and other parameters of t he knitted fabric on the elastic properties of the composite material are d escribed.