Low order plate bending elements with enhanced strains

Two variational formulations are considered for the development of low order plate bending elements. For the constitutive equation, the three-dimensional stress–strain relations are used without any modification. No shear correction factors are necessary in the formulation. Bilinear functions are used to approximate the deflection, the two rotations and the thickness change of the plate. The key ingredients in the low order formulation are the inclusion of the thickness change and the use of enhanced strain terms.