Abstract: Finite element analysis and optimization subject to stress, displacement and side constraints for composite sandwich structures are mainly treated in this paper. Square isoparametric sandwich plate / shell elements are used to perform the structural analysis. The thicknesses of the faceplates and the depth of the core are taken as design variables in optimization process. The number of layers for each laminate is taken as design variables if the composite faceplates are used. A few widely applied approximation concepts, such as design variable linking, regionalization method and temporary deletion of passive constraints are employed to reduce the number of both design variables and contraints. The advanced hybrid approximation techniques combining with dual solutions are employed in optimization. The corresponding software is applied to the analysis of experimental model and to the optimum design for the composite sandwich front-fuselage, and satisfactory results are obtained.

Key words: composite structures, sandwich structures, finite element analysis, optimum designs