Structural analysis and multidisciplinary design of flexible fluid loaded composite canard
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Mechanical performance of a composite canard subject to static aerodynamic loads was numerically studied in the present research. The canard was modeled as a symmetrically laminated curved panel, consisting of 8 plies of T300/5208 graphite/epoxy composite laminate. Modeling of this structure-fluid interaction system involves the coupling of two formulations: the solid classically treated in FEM formulation, and the fluid described by potential panel method in CFD. A structure-fluid iterative loop was implemented to simulate the relationship between the deformed aircraft wing and aerodynamic load. The outcome of the structural analysis indicated that the ply orientation have a significant effect on the mechanical performance of the composite laminates such that various design objectives can be achieved just by selecting the proper arrangement of ply orientation and thickness. Three numerical optimization techniques were applied respectively in the structural optimization design which aims at achieving the best structural performance and material efficiency while satisfying certain constraints. Gradient-based CONMIN converged quickly but only provided local optimum values. Probabilistic algorithm GA was capable of achieving the global/near-global optimums but the searching process was time-consuming. HYBRID, an automated hybridization process which combined GA and CONMIN together, has been implemented so that a single run of the algorithm gives a global optimum at reasonable computational cost. A structurally optimized design of the composite canard with lighter weight and higher stiffness has been obtained. A morphing design was performed on this structurally optimized composite panel to improve its maneuverability. An advanced design of composite canard with high structural efficiency and good maneuverability has been obtained by adjusting the ply angles. The strain energy of the host structure decreased which helps reduce the mechanical energy loss and improve the performance of the embedded or bonded actuators/sensors. The improved mechanical performance of the advanced design indicates that the adaptive laminated composite structures enhance the possibility of achieving a multi-functional structure for high performance structural applications.