Date of Award

Winter 2001

Document Type


Degree Name

Doctor of Philosophy (PhD)


Mechanical & Aerospace Engineering


Aerospace Engineering

Committee Director

Chuh Mei

Committee Member

Osama Kandil

Committee Member

Jen-Kuang Huang

Committee Member

Donald Kunz


A coupled structural-electrical modal finite element formulation for composite panels with integrated piezoelectric sensors and actuators is presented for nonlinear panel flutter suppression under yawed supersonic flow. The first-order shear deformation theory for laminated composite plates, the von Karman nonlinear strain-displacement relations for large deflection response, the linear piezoelectricity constitutive relations, and the first-order piston theory of aerodynamics are employed. Nonlinear equations of motion are derived using the three-node triangular MIN3 plate element. Additional electrical degrees of freedom are introduced to model piezoelectric sensors and actuators. The system equations of motion are transformed and reduced to a set of nonlinear equations in modal coordinates. Modal participation is defined and used to determine the number of modes required for accurate solution.

Analysis results for the effect of arbitrary flow yaw angle on nonlinear supersonic panel flutter for isotropic and composite panels are presented. The results show that the flow yaw angle has a major effect on the panel limit-cycle oscillation amplitude and deflection shape. The effect of combined aerodynamic and acoustic pressure loading on the nonlinear dynamic response of isotropic and composite panels is also presented. It is found that combined acoustic and aerodynamic loads have to be considered for high aerodynamic pressure values.

Simulation studies for nonlinear panel flutter suppression using piezoelectric self-sensing actuators under yawed supersonic flow are presented for isotropic and composite panels. Different control strategies are considered including linear quadratic Gaussian (LQG), linear quadratic regulator (LQR) combined with the extended Kalman filter (EKF), and optimal output feedback. Closed loop criteria based on the norm of feedback control gain (NFCG) and on the norm of Kalman filter estimator gain (NKFEG) are used to determine the optimal location of piezoelectric actuators and sensors, respectively. Optimal sensor and actuator locations for a range of yaw angles are determined by grouping the optimal locations for different angles within the range. The results demonstrate the effectiveness of piezoelectric materials and of the nonlinear output controller comprised of LQR state feedback and EKF nonlinear state estimator in suppressing nonlinear flutter of isotropic and composite panels at different flow yaw angles.