In recent times, the development of efficient plate bending elements has mostly used Mindlin's first-order shear deformation theory. Using this approach, independent assumptions may be made for the transverse displacement and normal rotations. Elements derived from this basis only require C0 continuity, which is readily achieved. Moreover, the theory is applicable to both thick and thin plates.

Despite these advantages, there are a number of problems associated with Mindlin elements. Specifically, elements can lock as the plate thickness approaches zero, or have zero energy modes. Many techniques, such as reduced integration, special shear interpolation and stabilization matrices, have been used to alleviate these problems. Despite the success of such techniques, there appears to be a need to develop Mindlin elements that will work for both thick and thin plates without the need for any special techniques.

The present paper discusses alternative formulations for deriving thick plate elements. In particular, the interpolation for the transverse displacement and rotations are such that the governing equations of Mindlin's theory are exactly satisfied. The resulting element approximation is consistent for both thick and thin plates, and no locking occurs in the thin plate limit.

A number of alternative formulations are possible based on such interpolations. The applications and advantages of these approach are presented and compared. Examples are given in the paper to demonstrate the accuracy that is achieved with the proposed elements.