UNIFIED FORMULATION FOR FINITE ELEMENT THERMOELASTIC ANALYSIS OF MULTILAYERED ANISOTROPIC COMPOSITE PLATES A. Robaldo and E. Carrera DIASP Politecnico di Torino, Turin, Italy A. Benjeddou Institut Supe ´rieur de Me ´canique de Paris, Paris, France This article presents various finite plate elements for the thermal stress analysis of multi- layered anisotropic structures. Assumptions are made for the displacement fields in thick- ness direction and the principle of virtual displacements (PVD) is employed to derive finite element (FE) matrices. The unified formulation is employed so that these FE matrices have been derived in terms of a few fundamental nuclei whose form is not affected by number of the nodes of the elements or order of the expansion for the displacements- variable description (layer-wise (LW) and equivalent single layer (ESL) cases are both addressed). The Murakami zig-zag function is used to introduce zig-zag effects in the framework of ESL descriptions. The performances of the derived finite elements, in terms of displacement and stress fields, are shown by solving thermal stress problems related to cross-ply laminated plates for various thickness ratio values. Comparison to closed form solutions as well as to available 3-D exact analyses have shown the effectiveness of the proposed elements and their capability to trace quasi 3-D descriptions of thermal stresses in layered plates. INTRODUCTION Temperature variations often represent a contributing factor and sometimes even the predominant cause of failure of engineering structures. These structures often consist of beams, plates, shells, etc., that are made of multilayered materials. Some examples of multilayered materials can be found in the advanced composite materials that were developed for aerospace vehicles (launching=reentry vehicles and fighter aircraft) during the second part of the last century. Biomedical retina, reactor vessels, turbines, advanced optical mirrors, semiconductor technologies, and space antennas are further examples of multilayered structures that can be sub- jected to severe thermal environments. An adequate knowledge of the deflections and stresses induced by thermal loads in these structures is of prime interest for structural analysts. The excessive Communicated by Liviu Librescu on November 25, 2004. Address correspondence to Erasmo Carrera, Aerospace Department, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Torino, Italy. E-mail: erasmo.carrera@polito.it 1031 Journal of Thermal Stresses, 28: 1031–1065, 2005 Copyright # Taylor & Francis Inc. ISSN: 0149-5739 print/1521-074X online DOI: 10.1080/01495730590964963