Optimum design of laminated composite plates for maximum thermal buckling loads

Buckling temperatures of graphite/epoxy laminated composite prates are maximized for a given total thickness considering fiber-directions and relative thicknesses of layers as design variables. Thermal buckling analysis is carried out using the finite element method with 4 node shear deformable plate element, while genetic algorithm (GA) is employed to optimize as many as ten variables for the five layered plates. In addition to traditional three-operator approach, i.e., reproduction, crossover and mutation, other variants of GAs such as the elitist model, two-point crossover models are also discussed. The study includes composite plates of three different aspect ratios, two support conditions and three different numbers of layers. The presented results reveal that the buckling loads can be increased significantly with appropriately orienting the fiber directions and varying the thickness of different lavers. The authors also recommend the judicious selection of specific thicknesses and fiber orientations needed for the practical implementation highlighting the importance of their theoretical values so that they may also be made available in near future for fabrication.