Interaction of ultrasonic surface waves with surface-breaking cracks
Date Issued
December 1, 1980
Author(s)
Butler, Daniel L.
Advisor(s)
Laszlo Adler
Additional Advisor(s)
Bruce Dewey
Abstract
Various phenomena have been observed when a bounded acoustic beam is incident upon a liquid/solid interface at or near the Rayleigh angle. These phenomena include: a shift of the reflected beam from the position predicted by geometrical acoustics, a null within the reflected field, a 180° phase reversal on either side of the null, and a weak trailing field on only one side of the reflected beam. Bertoni and Tamir presented a theory to describe these effects. A model was developed which describes the reflected field when it interacts with tight fatigue cracks. This model incorporated a transmission coefficient derived by Hou and Bertoni for a liquid-filled slip crack. Combining these two theories, the model predicted the reflected field after its interaction with fatigue cracks.
Experiments were performed to study the reflected field at an incident bounded beam at the Rayleigh angle with surface breaking defects in titanium, stainless steel, and carbon steel. Two types of defects were considered: tight fatigue cracks, and saw cuts. In the case of the saw cut the reflected field included the specular reflection, leaky component with a superimposed diffraction field. The reflected field from the tight fatigue crack included the specular reflection and an attenuated leaky wave component. The assumed model shows reasonable agreement to the experimental results.
Degree
Master of Science
Major
Engineering Science
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Thesis80B885.pdf
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