Investigations On The Actuating And Sensing Behavior Of Metal Core Piezoelectric Fibers

Metal core piezoelectric fiber is one of the new types of piezoelectric devices used for actuators and sensors. Depending on the electrode coated on the surface of the fiber, it can be categorized as the full coated metal core piezoelectric fiber (MPF) and half coated metal piezoelectric fiber (HMPF). Since each fiber contains two electric electrodes, an MPF or HMPF can be used either as a sensor or an an actuator. The MPF will be found extensive application for smart material and structure because of its geometry. For its optimiazation design and future usage in smart structure, the actuating and sensing behaviors of the MPF and the HMPF are systematically investigated. The major contributions and novel research results in the dissertation are summarized as follows.1. Based on the energy method, the constitutive equations of the cantilever MPF and HMPF in matrix forms are established. By using the established constitutive equations, the tip elongationδand the electrical charge Q on the electrodes of the MPF, subjected to an axial force F and an external voltage V, have bee obtained. And the tip angleα, the tip deflectionδ, the aerial displacement A and the electrical charge Q on the electrodes of the HMPF, subjected to an external voltage V on the electrodes, a bending moment M at its free end, a lateral force F at its tip, and a uniformly distributed load p on the HMPF have been obtained.2. Based on the vibration theory and the average distributed electrical charge method, the dynamic constitutive equations of the cantilever MPF and HMPF in matrix forms are established. By using the established dynamic constitutive equations, the dynamic tip elongationδand the dynamic electrical charge Q on the electrodes of the MPF, subjected to an axial dynamic force and an external dynamic voltage, have been computed. And the dynamic tip angleα, the dynamic tip deflectionδ, the dynamic aerial displacement A and the dynamic electrical charge Q on the electrodes of the HMPF, subjected to an external dynamic voltage V applied on the electrodes, a dynamic bending moment M at its free end, a dynamic lateral force F at its tip, and a dynamic uniformly distributed load p on the HMPF, have been obtained.3. The actuator of the cantilever MPF and HMPF are researched in details. The mechanical models of the two actuators were established based on their corresponding established constitutive equations. The effects of the radius and Young's modulus of the metal core on the behaviors of the MPF and HMPF actuators, including the tip elongation, the equivalent force, the resonance frequency, the electromechanical coupling coefficient, maximum energy transmission coefficient and maximum mechanical output energy, are studied.4. Several MPF and HMPF sensors were designed, including the static electrical charge type MPF strain sensor, the electrical charge (or electrical voltage) type HMPF dynamic micro force sensors. The mechanical models of these sensors were derived based on their established static and dynamic constitutive equations. The effects of the radius and Young's modulus of the metal core on the behaviors of the MPF and HMPF sensors were studied theoretically. And the sensing properties of these sensors were studied experimentally.5. Based on the static and dynamic constitutive equations of the cantilever MPF and HMPF, static and dynamic models for measuring piezoelectric parameters were proposed, and testing methods for measuring the piezoelectric parameters were designed. Then piezoelectric parameters of some MPF and HMPF were measured experimentally.