A Three-Dimensional Laminated Plate Finite Element with High-Order Zig-Zag Sublaminate Approximations

This paper describes a new laminated composite plate theory and associated finite element model that allow variable through-the-thickness refinement, as needed, to capture higher-order thickness effects and interlaminar stresses in laminated composite and sandwich panels. The theory and finite element model utilize a new zig-zag sublaminate concept, in which each computational layer (or sublaminate) contains several, even many, physical layers. Within each sublaminate, a high-order zig-zag kinematic assumption is employed, providing very high accuracy, even when the entire laminate is modeled using only a single sublaminate. The accuracy and efficienty of the model are thus adaptable, depending upon the number of sublaminates used. In order to facilitate through-the-thickness refinement, the finite element model is cast in the form of an eight-noded brick-type element, with displacements and rotations as nodal degrees-of-freedom. At interlaminar element boundaries, interlaminar shear traction degrees-of-freedom are also present, so that transverse shear stress continuity can be enforced through the entire thickness of the laminate, irrespective of the thickness discretization chosen. Numerical examples are presented to demonstrate the effectiveness of the current model for the analysis of laminated composite and sandwich panels that are very thick or thin.