Anisotropy and symmetry for elastic properties of laminates reinforced by balanced fabrics

In this article, we present a theoretical study on elastic properties of la minates composed by balanced fabric layers. Using the polar representation method for plane elastic tensors, we first describe some properties of symm etry of a general laminate composed by balanced fabrics and we write the fo rmulas expressing positions of its axes of symmetry. Then, limiting our stu dy to laminates composed of identical plies, we solve two problems of symme try of the laminate elastic tensors: uncoupling and quasi-homogeneity, We f ound all the solutions of the uncoupling problem for the case of 3-, 4- and 5-ply laminate and all those of the quasi-homogeneity problem for the case of 4-, 5- and 6ply laminate: it is worth noting that this class of solutio ns was not known before. (C) 2001 Elsevier Science Ltd. All rights reserved .