Flutter Instability of Aircraft Swept Wings by Using Fully Intrinsic Equations

In this paper, the dynamic instability of swept wings by using the geometrically exact fully intrinsic beam equations is investigated. Due to the lack of existence of sweep angle effects in the aeroelastic formulation of these equations, this study is aimed to add the effect of sweep angle to the aforementioned formulation and this is one of the aspects of innovation in this paper. The fully intrinsic equations involve only moments, forces, velocity and angular velocity, and in these equations, the displacements and rotations will not appear explicitly. For this reason, the important advantages of these equations are complete modeling without any simplifying assumptions in large deformations, low-order nonlinearities and thus less complexity. In order to determine the stability of the wing, first the resultant non-linear partial differential equations are discretized by using the central finite difference method, and then linearized about the static equilibrium. Afterward, using the eigenvalueanalysis of linearized equations, the stability of the system versus different parameters is evaluated. The obtained results are compared with those available in the literature, and good agreement is observed. Finally, it is observed that by using the fully intrinsic equations, the instability of the swept wings can be determined accurately.