Nonlinear body-freedom flutter analysis in aircraft with the flexible wing

In aircraft with flexible high aspect ratio wings, it is possible to couple flight dynamics modes and aeroelasticity. This coupling can lead to the body-freedom flutter (BFF) phenomenon, which is the subject of this article. In this study, the planar flight dynamics assumption and the model of a complete aircraft with flexible wings have been used. In this type of aircraft, due to the high aspect ratio of the wings, the effects of nonlinear terms on the dynamic response of the aircraft cannot be ignored. Therefore, for modeling the structure, the generalized nonlinear flexible Euler-Bernoulli beam model with bending-bending-torsion degrees of freedom and for modeling the aerodynamics, the Wagner function with the static stall model has been used. Using the developed model, the nonlinear behavior of the wing and the aircraft due to the occurrence of the BFF and wing flutter (WF) is studied. Also, a sensitivity analysis for the BFF is done and post-instability limit cycle oscillations and subcritical behaviors are investigated.