Semi-Active Flutter Suppression Of A Wing Using Magnetorheological Dampers

Recently, application of semi-active control strategies and semi-active control devices in civil engineering and other control problems has been developed. In particular, the semi-active control based on magnetorheological (MR) dampers has been attracted considerable attention for its simple mechanism, low energy requirement, high robustness and flexible control algorism. In this study, the application of the semi-active control based on MR dampers to suppress the flutter and the limit cycle oscillation (LCO) of aeroelastic systems is performed.(1) An aeroelastic system of three degrees of freedom, which includes a two-dimensional airfoil section with a control surface and a MR damper is discussed. The MR damper is installed on the aileron rotation axis. The clipped-optimal control strategy is performed in the semi-active flutter control of the aeroelastic system. The numerical simulations based on the Theodorsen's aerodynamic load suggest that the MR damper is able to increase not only the structure damping, but also the critical flutter speed. After which, three passive flutter control strategies of the system is performed, and the numerical simulation results of the passive cases are compared with the semi-active case.(2) This part of the paper discusses a method that deals with a high-aspect-ratio (HAR) wing-aileron system through the use of multiple MR dampers mounted on the hinge axis along span-wise. The aerodynamic equation of the whole HAR wing-aileron system is reached through the use of strip theory. To verify the aerodynamic equation, a comparison of the numerical simulation results between Matlab-Simulink model of the equation and MSC.Flds model is performed. The effect of the structural parameters on the flutter characteristics is discussed in detail. The numerical simulation shows that the semi-active control strategies based on multiple MR dampers hold promise in suppressing the flutter of an entire HAR wing with aileron.(3) Nonlinear aeroelastic systems of three degrees of freedom wing section and HAR wing are established by introducing a nonlinear structural stiffness respectively. Clipped-optimal control based on MR dampers is performed to suppression the nonlinear flutters and the LCOs of the nonlinear aeroelastic systems. Numerical simulations show the effectiveness of the control strategy in suppressing the LCOs of nonlinear aeoelastic systems. This research is partially supported by the National Natural Science Foundation of China under Grant No.50478037 and No.10572058 and the Research Fund for the Doctoral Program of Higher Education under Grant No.20050287016.