Analytical Investigation of Aero-Elastic Behavior of Aircraft Composite Box Wings in Unsteady Compressible Flow

In this study, an anisotropic thin-walled “Composite Box Beam” as the “Wing System” is used to consider the effects of the fiber orientation and the lay-up configuration on the aeroelastic stability and the dynamic response of an aircraft wing. The present “Circumferentially Asymmetric Stiffness Model (CAS)” takes into account a group of non-classical effects; such as the transverse shear, the material anisotropy, warping inhibition, etc. The “Aerodynamic Strip Method” based on “Wagner Functions” in unsteady compressible flow are used to simulate compressible unsteady aerodynamic effects in the “state space” form. In addition, the mass, the stiffness and the damping matrices of the present non-conservative aeroelastic system are formed so that, the “Extended Galerkin’s Method (EGM)” and the “Separation of Variables Method” can be employed. As a result, the coupled and linear “Governing System of Dynamic Equations” are obtained. After then, by transforming matrices into the “state space” and “state vector” forms, the problem under study is finally converted into an “Eigenvalue Problem and Analysis”. Hence, the “flutter” and the “divergence” speeds for various layer configurations with different geometric and material properties and fiber orientations were obtained. Furthermore, by solving the aforementioned equations of motion in the time domain, the aeroelastic responses of the “Composite Box Wing System” for different flight regimes are computed. The present numerical results were compared and are verified with some existing experimental results in the literature. Based on these, some brief but important conclusions are presented.Copyright © 2011 by ASME