Optimal design of composite lifting surface for flutter suppression with piezoelectric actuators

This paper presents the optimal design of an active flutter suppression system for an adaptive composite lifting surface. Rayleigh-Ritz method is used to develop the equations of motion of a laminated plate-wing model with segmented piezoactuators. A state space aeroservoelastic mathematical model by rational function approximation (RFA) of the unsteady aerodynamic forces is derived. The minimum state method combined with the optimization technique is adapted for RFA. The linear quadratic regulator with output feedback is employed in active control of the system. The thickness and size of the piezoelectric actuators that affect the structural properties as well as the control characteristics are held constant. The optimal placement of piezoelectric actuators for flutter suppression subject to minimize the controller performance index is determined analytically by using the optimization technique. The results show the capability of piezoactuators for the control of wing flutter. Numerical simulations of a model with the optimal actuators placement show a substantial saving in control effort compared with the initial model.