Abstract: Theoretical and experimental investigations are performed for the scheme of" fluttertaming"-semi-active control of structural nonlinear flutter. First, for a two-dimensionalnonlinear flutter system, the digital simulation method is used to analyze the principle of semi active control and to study the response characteristics of the system with control element. Simulation results show that, by using limit cycle characteristics of structural nonlinear flutter and automatical control technique, the nonlinear stiffness parameter of the flutter system can be adjusted automatically and hence the amplitude of the flutter response of the system can be suppressed into a very small stable region. In accordance with the analytical model, a wind tunnel test model of semi - active flutter control is designed: the monitoring of response signal and the controlling of stiffness adjusting micromotor are performed by an 8031 microprocessor. Wind tunnel tests show that the nonlinear flutter can be controlled effectively by this technique. This study provides a new approach of flutter suppression.

Key words: nonlinear flutter semiactive control, tlutter taming