Anisotropic wave guides-- propagation, focusing and dispersive phenomena with applications for non-destructive testing.

Abstract

Acoustic Non-Destructive Testing (NDT) has a long history of applications in fatigue monitoring, fault testing, and more recently production control. A very large family of manufactured and raw materials consist of thin layers. Some examples include rolled aluminum, window glass, plywood, automobile bodies, plane wings, silicon wafers, bridge support beams, and paper. These layers can be viewed and modeled as acoustic waveguides. This thesis will present the framework in which to analyze such layers. To this end, analytic solutions to the plane wave displacement and stress fields in a single layer monoclinic material will be presented The propagation, frequency, and dispersive characteristics of transmitted signals can be analyzed to determine various elastic properties of the layer or to identify faults. Wavelet (time-frequency), Fourier (frequency), and signal matching (time) techniques will be developed to analyze and extract features and properties of signals. Several experimental examples will be presented.