TWO THIN PLATE ELEMENTS DEVELOPED BY ASSUMING ROTATIONS AND USING QUADRILATERAL AREA COORDINATES

Two 4-node, quadrilateral generalized conforming thin plate elements, AΨQ-I and AΨQ-II, were successfully developed by directly assuming rotation field and using quadrilateral area coordinate method. By requiring low order and high order terms of the assumed rotation fields to be compatible with the corresponding terms of the boundary rotations, the element rotation fields achieve third order completeness. Comparing with the famous element DKQ constructed by the similar technique but using isoparametric coordinates, the two new elements are insensitive to mesh distortion and able to offer more accurate results.