Modeling and control design of smart structures bonded with piezoceramic actuators and sensors

This dissertation presents a detailed study of the modeling and control design of structures using bonded piezoceramic actuators and sensors. Piezoceramics transducers are employed to control pure bending, pure torsion and combined bending/torsional vibration. The important features of the work presented here are (i) the modeling of actuator/sensor dynamics that result when piezoceramics are used as transducers, (ii) the effects of transducer size and location, (iii) the finite element modeling and simulation of the structure and (iv) the verification of the simulation results with experimental data.; In this thesis, the problem is approached from the viewpoint of control design. Discrete sensors and actuators are used for the multimode control of bending and torsional vibration of structures. The sensors and actuators considered in this study are piezoelectric ceramics composed of lead zirconate titanate (PZT). The electro-mechanical coupling inherent in piezoelectric ceramics makes them ideal transducers. This work addresses the issues of strain transfer, transducer location and transducer size.; The structures studied in conjunction with thickness mode driven actuators include a cantilever beam, T-beam and a clamped plate. Optimal control theory is used to design controllers for these structures and Kalman filters are used to estimate the structural displacements and velocities. The finite element code ANSYS is used for mode-frequency analysis of these structures. The structural response to external disturbances with and without the piezoelectric transducers is studied numerically. The numerical simulations are compared with experimental results.; In this work it is shown that discrete sensors and actuators are to be preferred over distributed actuators and sensors for multimode control. The strain transfer ratio is shown to be a function of the material properties and the thickness ratios. In the case of beams it is shown that control effectiveness is maximized by locating the transducers at points of maximum strain. These results are used to control closely spaced modes of a T-beam structure. The results are then extended to two-dimensional, plate structures and the optimality of transducer location and transducer size are discussed. The results have been used in the modeling and simulation of a micropump.