Abstract:
This dissertation deals with the active control of flexural vibration of annular plates through the design of two new piezoelectric fiber composite (PFC) actuators in the cylindrical coordinates. The first one is an extension mode PFC actuator, and the next one is a shear mode PFC actuator. The extension mode PFC is basically a cylindrically orthotropic short piezoelectric fiber composite (SPFC) in the shape of a thin annular disc. This annular SPFC disc is comprised of unidirectional short piezoelectric fibers embedded in the epoxy matrix. The longitudinally poled short piezoelectric fibers are oriented in the radial direction so that the extension mode piezoelectric actuation appears along the radial direction in response to an externally applied coaxial electric field. The effective electro-elastic properties of this SPFC actuator are estimated by developing a finite element (FE) procedure, and the changes in the properties due to the use of unidirectional short/discontinuous fibers (SPFC) instead of the continuous fibers (CPFC) are demonstrated. A fruitful arrangement of surface-electrodes over the top and bottom surfaces of the annular SPFC/CPFC disc is proposed, and its (SPFC/CPFC) actuation capability is investigated in active control of harmonically excited flexural vibration of an annular substrate plate.
