C⁰-continuous triangular plate element for laminated composite and sandwich plates using the {2,2} - Refined Zigzag Theory

Most of the existing plate elements assume constant transverse displacement across the thickness resulting in zero transverse stretch deformation. This study presents a new triangular finite element for modeling thick laminates and sandwich panels based on the {2,2}-order refined zigzag plate theory. It adopts quadratic through-thickness variation of the in-plane and transverse displacement components. The transverse normal strain is calculated based on the assumption of cubic representation of the transverse normal stress. The zigzag functions are piecewise linear through the thickness. The element consists of 3 corner nodes and 3 mid-side nodes along the edges. Each corner and mid-side node has 11 and 3 degrees of freedom (DOF), respectively. This C⁰ continuous element is free of geometric locking, and does not require shear correction factors. It provides robust and accurate prediction of all six stress components (in-plane and transverse normal and shear stresses) in the analysis of highly heterogeneous laminates and sandwich plates.