Modeling and Control Design for Flutter Suppression Using Active Dynamic Vibration Absorber

Background: Enhancing the efficiency of modern aeronautic structures necessitates flexibility increasing associated with weight reduction. A consequent possibility of unfavorable unsteady aeroelastic phenomena such as flutter arises due to the interaction between the elastic, aerodynamic, and inertia loads. Researchers work hard to suppress it using numerous passive and active techniques. Purpose: This paper presents the mathematical model and the optimal control of an active technique for flutter mitigation of an airfoil system undergoing incompressible flow. Methods: The proposed active dynamic vibration absorber (ADVA) comprises an active element together with a classical mass–spring–damper system. In the active mode, a controlling force is generated by the active element to actuate the mass using feedback from the vibration responses of the aeroelastic airfoil system. A non-dimensional mathematical model for a typical two-degree-of-freedom aeroelastic airfoil integrated with the ADVA is introduced based on unsteady aerodynamic theory. The effect of the ADVA parameters on the aeroelastic system stability is investigated in different flight conditions. Additionally, two feedback controllers are presented to analyze the closed-loop system. The control gains are optimized based on a genetic algorithm to improve the performance of the proposed ADVA. Results: Introducing the passive dynamic absorber increases the flutter speed by about 15%, while activating the ADVA at the new flutter speed stabilizes the system and further expands the airfoil flutter boundaries. Conclusion: The proposed ADVA ensures flutter suppression and extends the flutter boundary. Furthermore, the introduced flutter control technique is robust against the variation of the system parameters and the detuning of the ADVA parameters.