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The shear horizontal wave propagation and vibration of piezoelectric coupled structures under an open circuit electrical boundary condition are studied. Following the studies on the dynamic response of piezoelectric coupled structures, the repair of both crack/notch and delaminated structures using piezoelectric materials are conducted. The main contribution was the proposed the active structural repair design using piezoelectric materials for different structures. An accurate model for the piezoelectric effect on the shear wave propagation is first proposed to guide the application of piezoelectric materials as sensors and actuators in the repair of engineering structures. A vibration analysis of a circular steel substrate surface bonded by a piezoelectric layer with open circuit is presented. The mechanical models and solutions for the wave propagation and vibration analysis of piezoelectric coupled structures are established based on the Kirchhoff plate model and Maxwell equation. Following the studies of the dynamic response of piezoelectric coupled structures, a close-loop feedback control repair methodology is proposed for a vibrating delaminated beam structure by using piezoelectric patches. The electromechanical characteristic of the piezoelectric material is employed to induce a local shear force above the delamination area via an external actuation voltage, which is designed as a feedback of the deflection of a vibrating beam and a delaminated plate, to reduce the stress singularity around the delamination tips. Furthermore, an experimental realization of an effective repair of a notched cantilever beam structure subjected to a dynamic loading by use of piezoelectric patches is reported. A small piezoelectric patch used as a sensor is placed on the notch position to monitor the severity of the stress singularity around the notch area by measuring the charge output on the sensor, and a patch used as an actuator is located around the notch area to generate a required bending moment by employing an actuation voltage to reduce the stress singularity at the notch position. The actuation voltage on the actuator is designed from a feedback circuit process. Through the analytical model, FEM simulation and experimental studies, the active structural repair method using piezoelectric materials is realized and proved to be feasible and practical.

Research Doctorate - Doctor of Philosophy (PhD) / Mechanical structures encounter vibration in response to environmental conditions and dynamic loads. In most circumstances, vibration contributes to mechanical fatigue which can eventually lead to catastrophic failure. Consequently, vibration control is a necessity for prolonging the operational life of structures. Piezoelectric and electromagnetic transducers have been used for control of vibration for many years. They normally sense mechanical vibration and generate an opposing vibration through another piezoelectric and electromagnetic transducer. This is usually referred to as active feedback vibration control. Another vibration control strategy senses and actuates simultaneously through an appropriately designed electrical impedance which is connected to the terminals of a single transducer. This technique requires no additional sensor, has improved robustness and stability, and a similar feedback structure compared to active feedback vibration control. The objective of this thesis is to develop new vibration control techniques by expanding on both the previously mentioned strategies. The first part of this thesis considers connecting an electrical impedance to a piezoelectric transducer to control vibration. This part reinforces that this vibration control strategy can be modelled as a variation of active feedback vibration control whereby the impedance parameterises the effective controller. A series of new vibration controllers are then presented. Applying the knowledge gained in the first part of this thesis, the second part considers replacing the piezoelectric transducer with an electromagnetic transducer. Although the underlying dynamics and physical properties of the transducers are different, the feedback structures are remarkably similar to that of active feedback vibration control. A number of new vibration control strategies are proposed for a variety of mechanical systems. Throughout the thesis, theoretical ideas and concepts are experimentally compared and validated on simple mechanical apparatuses to evaluate their vibration control performance.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2007. / Title from title screen (site viewed Feb. 22, 2008). PDF text: x, 136 p. : ill. (some col.) ; 18 Mb. UMI publication number: AAT 3275065. Includes bibliographical references. Also available in microfilm and microfiche formats.

Thesis (M.Eng.). / Written for the Dept. of Mechanical Engineering. Title from title page of PDF (viewed 2008/12/04). Includes bibliographical references.

Thesis (M.S. in mechanical engineering)--Washington State University, August 2008. / Includes bibliographical references.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 153-157). Also available via the Internet.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 98-100). Also available via the Internet.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 63-65). Also available via the Internet.