Flutter Analysis of Adaptive Wing with the Adjustment of Spar Position

In this paper, the flutter of an adaptive wing with adjustment of spar position is studied. Despite of two-dimensional models which was used in earlier research on this subject, in this study, more realistic model of the wing with adjustment of spar position contains sweep angle and unsteady aerodynamic loadings is employed. Two uniform spars which can move in chordwise direction are considered along the wing. The wing bending and torsion equations of motion have been derived by Hamilton’s principle. In order to use this principle, kinetic energy, strain energy and virtual work of forces have been obtained for spars and wing separately and then their sum embedded in the Hamilton’s principle. To simulate the aeroelastic loading on the wing Peter’s unsteady aeroelastic model is used. Assumed mode method has been used to discretized the aeroelastic governing equations and the numerical results has been validated with previous published papers, which good agreement has been reported. To review and presentation of results, four different types of motion for two spars have been utilized. In each type of motion, initial and final situation of spars are considered based on their velocity. Comparison of adaptive wing with simple wing in the same conditions shows that flutter velocity and frequency increases for adaptive wing. Finally, effects of different design parameters on the aeroelastic behavior of adaptive wing have been evaluated. Results indicate that these parameters can influence the stability region of such wings, significantly. Results indicates that increasing the thickness of the wing skins and spars reduces the wing flutter speed.