| The practical application of wave phenomena involves a number of areas in science and technology. In some non-destructive examination (NDE) techniques, elastic waves are used to determine fundamental properties of the materials or to locate flaws in the structure. In signal processing, bulk waves and surface acoustic waves (SAW) are used in ultrasonic delay lines and SAW devices. The primary means for generating or detecting waves in these applications are piezoelectric transducers.;Recent interest in developing smart structures has created new demands for employing novel NDE techniques as an integral part of the structure. To this end, interdigital (ID) transducers, widely used in SAW devices, can be employed to generate and detect ultrasonic waves and thus, probe the interior of an object for damage detection.;The solution of elastic wave problems in complex geometries using analytical methods can be extremely difficult. Inclusion of piezoelectric effects obviously increases this complexity. However, the finite element method is a powerful numerical technique and can be employed to simulate the elastic wave propagation in piezoelectric integrated structures. Regardless of the complexity of the geometry and material properties, time history analysis, harmonic and transient responses of piezoelectric devices or media can be performed using this method.;In this dissertation, a finite element formulation for three dimensional modeling of static and dynamic response of structures with piezoelectric components and the development of highly-efficient closed form expressions for element electroelastic stiffness matrices for straight-sided LST and QST tetrahedral elements are presented. The resulting finite element formulation is employed to perform numerical simulation of elastic bulk waves generated by piezoelectric transducers. Experimental observations of flexural waves generated by surface mounted piezoceramic plates are compared with the finite element results as well. Bulk wave generation and detection using interdigital electrodes deposited on piezoceramic substrates is simulated and their potential application as probes in smart structures is discussed. |
