Analysis of laminated composites composed of coupled layers by polar method

Abstract

Composite laminated plates are made of two or more unidirectional plies (or layers) stacked together at various orientations, the layers are composed of two phases: the fibers and the matrices. The material property and orientation of the fibers inside of the matrix determines the elastic characteristics of the layers. If the conventional layers used to fabricate laminate, there is no elastic coupling between bending and extension, other types of layers (the satins for example) have coupled behaviors. The classical lamination theory (CLT) formulates the elastic behavior of a laminate composed of classical layers, but it should be modified to be able to include these coupled layers that is the aim of the first part of this article. The second aspect of coupled layers must be considered: when they turned over, some of their elastic characteristics change, this phenomenon is studied in a second part and a method is proposed, including the reversal into the CLT equations, give more useful equations describing the laminates made of coupled layers. Finally, some cases of uncoupled and quasi-homogeneous stacking sequences are studied.