Active Control of Nonlinear Panel Flutter UsingAeroelastic Modes and Piezoelectric Actuators

Abstract

Suppression of nonlinear panel flutter at supersonic speeds has been investigated traditionally with system equations of motion in terms of in vacuo modal coordinates. For isotropic and symmetrically laminated orthotropic composite plates, the limit-cycle oscillations converged with six in vacuo natural modes at a zero yaw angle. However, as laminated composite plates undergo the effect of an arbitrary yawed flow angle, complicated characteristics emerge by increasing the required in vacuo natural modes for an analysis of limit-cycle oscillations. To design an effective controller, the large number of modes should be reduced. As a result, the small number of modes produces a capability to alleviate the costly computational effort in designing controllers for the suppression of nonlinear panel flutter. In the present study, aeroelastic modes that provide the reduced order basis are used for panel limit-cycle motion. Two or six to seven aeroelastic modes are implemented for developing an active controller of panel flutter with isotropic and anisotropic laminated composite plates at a zero or nonzero yaw angle. Along with the aeroelastic modal equations of lesser number, a linear quadratic regulator, which is one of the output feedback controllers, is constructed to suppress nonlinear panel flutter. An added extended Kalman filter compensates for the nonlinearity of structural motion resulting from updating the system information online. The norms of feedback control gain and the norms of Kalman filter estimation gain are employed for the optimal placement of PZT5A or macro-fiber composite piezoelectric actuators and sensors. Numerical results show that the designed controller based on aeroelastic modal coordinates can suppress the large-amplitude panel nonlinear flutter response. The maximum flutter-free dynamic pressure for isotropic and composite plates is evaluated to measure how much the performance is improved.