Structure of ultrasonic leaky waves and their interaction with subsurface flaws
- Oak Ridge National Lab., TN
Recent experiments and theoretical efforts indicate that the interaction of a bounded ultrasonic beam with a liquid-solid interface at the Rayleigh angle produces a specular reflection, which carries energy back into the liquid from the point of incidence, and a leaky Rayleigh wave, which propagates along the interface and continuously radiates into the liquid. Because the leaky wave penetrates only a few wavelengths below the solid surface, its potential for near-surface flaw detection has been investigated. An immersible acoustic goniometer system was used to measure the amplitude and phase distribution across the reflected beam from a water-metal interface for an incident Gaussian beam. This amplitude and phase distribution, which had been successfully compared to a theoretical model, was found to depend on the following test parameters: frequency, distance, beam width, and material properties. Specimens with and without artificial defects were investigated. The reflected (reradiated) field is altered when defects are present, as shown by these goniometer measurements and by schlieren photography.
- OSTI ID:
- 6634672
- Journal Information:
- Mater. Eval.; (United States), Vol. 35:5
- Country of Publication:
- United States
- Language:
- English
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