Aeroelastic Analysis And Control Of Flexible Wings Based On Plate Model

This thesis presents a systematic study on active flutter suppression of smart wings withpiezoelectric actuators and sensors by using direct/converse piezoelectric effect of piezoelectricmaterials. The wing model with cantilevered composite laminate plate has two-dimensional spanwiseand chordwise flexibility. Piezoelectric materials combine with the wing structure with its advantagesof flexible distribution, simple mechanism and quick response. The structures also haveself-monitoring and self-actuating capabilities, which can design feedback control systemconveniently. A pair or more piezoelectric actuators and sensors are distributed on flexible wing,theoretical analysis and simulation research on the modeling of electromechanical coupling systemare carried out, flutter of flexible wings is analyzed, the feedback control is designed for the system,and the effectiveness of the control method is studied. The main progresses and contributions of thisthesis are follows.A generalized finite element formulation is derived for modeling the composite laminate platecombined with piezoelectric actuator and sensor layers by using first-order shear deformation theory.The structure is discretized by four-noded quadrilateral isoparametric element. Substitute shear strainfields is used to avoid shear locking. Hamilton’s variational principle is used to derive the equations ofmotion. The effectiveness of the finite element model is validated through numerical examples.The doublet lattice method is used to model unsteady aerodynamic loads acting on the liftingsurface. Infinite plate spline method is used to connect structural motion and aerodynamics loading.And then derived the aeroelasticity equations based on frequency domain aerodynamics. The fluttervelocity and flutter frequency are obtained by V-g flutter analysis method. Numerical examplesillustrate the distributions of the pieoelectric materials have obvious effect on the flutter characteristic.In order to get time domain state-space aeroelastic equations, Roger approximation is used tofitting rational functions of frequency domain aerodynamics. Two controllers are designed using thenegative velocity feedback control and LQG control. First model use only one pair of piezoelectricactuator and sensor, the other model use multi-pairs of piezoelectric actuators and sensors. Activeflutter suppression is investigated numerically for these two models. The stability analysis andnumerical simulations of the closed-loop system demonstrate the effectiveness of the control methods.