Abstract

Panel forced-vibration and panel flutter are controlled by using piezoelectric actuation and iterative root locus design method. Although forced-vibration and flutter are essentially two different physical phenomena, their limit-cycle behaviors can both be modeled by a non-linear stiffness driven either by a forcing input or by an aerodynamic load. A nonlinear finite element dynamic model which incorporates these two driving terms has been developed for an aluminum panel with one-sided surface-mounted piezoelectric actuators. The first-order piston theory type relation is used to provide an adequate representation of the supersonic aerodynamic load. Surface strains and their associated strain-rates at various pre-determined locations on the panel are the system outputs for feedback. Input and output filters are used in the control loop in order to avoid aliasing and to minimize effects of noise on unmodeled high frequency modes. The importance of including the filters in the model is also demonstrated. The root locus design method is used iteratively to search for the local optimal output feedback gains either to increase modal damping for the forced-vibration case or to increase critical dynamic pressure for the flutter case. Although the control design is linear, it is shown to work adequately for the numerical simulations using non-linear system model. An experiment is performed to verify the forced-vibration results which serves as an inexpensive way of checking and/or modifying the panel flutter control design before a very expensive wind tunnel testing is arranged.

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