Koiter-Newton analysis of thick and thin laminated composite plates using a robust shell element

The Koiter-Newton method is a novel reduced-order modeling technique to efficiently trace the geometrically nonlinear equilibrium path of the structure in the presence of buckling. In this paper, the existing method is extended for nonlinear buckling analysis of thick and thin laminated composite plates. A 4-node quadrilateral element S4AT is developed as a geometric linear element in the co-rotational formulation of the Koiter-Newton method. The developed element S4AT is a combination of the membrane part and the plate-bending part. The quadrilateral area coordinate method is applied to make the element insensitive to the mesh distortion. The Reissner-Mindlin laminated composite plate theory is used to consider the transverse shear deformation effect, and the shear-locking phenomenon is eliminated using the Timoshenko laminated composite beam theory. The performance of the method in terms of reliability, accuracy and computational effort is demonstrated with several examples.