Modelling the elastic properties of knitted-fabric-reinforced composites

In this paper the elastic properties of knitted-fabric-reinforced composites ave investigated Tensile and shear tests were performed to determine the in-plane Young's modulus, Poisson's ratio and shear modulus of different types of glass/epoxy warp-knitted fabric composites. Some models are discussed for the prediction of the elastic constants, on the basis of the fibre orientation distribution, the constituent material properties and the fibre content. Apart from the Krenchel approach, two basic variants of simple three-dimensional models are evaluated. Depending on the averaging procedure used, upper and lower bounds for the elastic moduli ave found with the Voigt and Reuss method, respectively. These bounds ave shown to agree well with the experimental results for the Young's moduli and the shear moduli. Closer bounds are obtained by assuming that the matrix is uniformly distributed through the composite. These closer bounds are shown to be valid for the Young's modulus bur not for the shear modulus. The in-plane Poisson's ratio could not be predicted successfully. (C) 1996 Elsevier Science Limited