Structural and control optimization for maximum thermal buckling and minimum dynamic response of composite laminated plates

A multiobjective optimization problem is presented to determine the optimal layer thickness and optimal closed loop control function for a symmetric cross-ply laminate subjected to thermomechanical loadings. The optimization procedure aims to maximize the critical combination of the applied edges load and temperature levels and to minimize the laminate dynamic response subject to constraints on the thickness and control energy. The objective of the optimization problem is formulated based on a consistent first-order shear deformation theory without introducing a shear correction factor. The dynamic response is measured as the sum of the total elastic energy of the laminate and a penalty term involving a closed loop control force. Laipunov-Bellman theory is used to obtain solutions for the controlled deflections and optimal control force. The layer thickness is taken as a design variable, and is presented as a function of the number of layers. A numerical study is made for simply supported symmetric laminates with an odd number of layers to show the advantages of the present control optimization. The study indicates that the present control optimization is active with most laminates cases for all values of aspect ratio, number of layers, orthotropy ratio, thermal expansions ratio and thickness ratio. (C) 2003 Elsevier Ltd. All rights reserved.