Asymptotic equivalence of DKMT and MITC3 elements for thick composite plates

This paper presents in a unified and comparative manner, the formulation of two triangular plate bending composite elements, i.e. DKMT and MITC3 which are published in 1993 and 2004. Both elements have 3 nodes and 5 dof per node (three displacements and two rotations), taking into account transverse shear effects. There are valid for thin to thick composite plates, and give good results in classical benchmark and patch tests. The numerical results using DKMT element show the optimal and uniform convergence for thin and thick plates with an advantage for DKMT compare to MITC3 due to semi quadratic interpolation for the rotation variables The present paper contains new convergence analysis based on the s-norm tests for sandwich plates considering uniform and distorted meshes, and for symmetric and non symmetric composite plates with 3 and 9 layers. As the novelty and main contribution of this article, we propose the shear projection method in the element formulations to show the asymptotic equivalence of DKMT and the MITC3 for thick to thin composite plates.