This paper describes the investigation into the optimization of composite wing structures for desirable aeroelastic behavior. The wing primary structure was modeled by an assembly of single-cell thin-walled box beams enclosed between the spars. Leading and trailing edge cells contributed to mass and inertia, and were counted for aerodynamic force calculation only. Based on the geometry, properties, and laminate layups, the bending, torsion, and bending-torsion coupling rigidities for each of the box beams were obtained. Using the dynamic stiffness matrix (DSM) method and neglecting the shear deformation and warping effect, the governing equations for a box beam in free vibration are represented. Comparing with the quasi-isotropic layup, there is a great potential for increasing the flutter speed by optimizing the fiber orientations of composite wing box laminates in all the cases studied in this paper. Comparing with the layup case that offers the maximum torsion rigidity, however, the effect of swept angle, taper ratio, and especially the mass distribution on aeroelastic tailoring is critical. The most effective tailoring is for a uniform nonswept wing box. In this case, a significant increase in flutter speed can be achieved due to a beneficial aeroelastic effect from the bending-torsion coupling rigidity CK. For a swept or geometrically tapered wing, however, the role of CK in the aeroelastic tailoring and hence the potential increase of flutter speed is largely reduced. In the above cases, the genetic algorithm (GA) is preferable to the gradient-based deterministic (GD) method. For a wing box tapered in geometry and mass, the influence of CK on aeroelastic tailoring becomes negligible. In this case, the torsion rigidity GJ dominates the flutter speed and the +/-45 laminate layup results in a near global optimum solution. Aeroelastic tailoring can be simplified to a process of searching for the maximum GJ instead of flutter speed. This will not only largely save computational time but also simplify design optimization. In such a case, the GD method is preferable to the GA method.
Aeroelastic tailoring of composite wing structures by laminate layup optimization
AIAA Journal (online) ; 44 , 12 ; 3146-3149
2006
4 Seiten, 3 Bilder, 4 Tabellen, 17 Quellen
Article (Journal)
English
Aerodynamik , Bewegungsgleichung , Einflussgröße , elastische Eigenschaft , Faserorientierung , Flatterschwingung , Flügelprofil , Fluid-Struktur-Wechselwirkung , freie Schwingung , genetischer Algorithmus , Gradientenmethode , Kastenträger , kritische Geschwindigkeit , Mehrschichtstoff , Optimierungsalgorithmus , Schichtstruktur , Tragfläche (Aerodynamik) , Tragwerk (Flugzeug) , Steifigkeit
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