[American Institute of Aeronautics and Astronautics 39th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference and Exhibit - Long Beach,CA,U.S.A. (20 April 1998 - 23 April 1998)] 39th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference and Exhibit - A higher order finite element for sandwich plates