Acoustic micrographs of samples containing subsurface cracks have been analyzed with a plate model which faces the coupling liquid above and a vacuum below. Minima have been found in the intensity of the reflected beam as a function of the thickness D of the plate when the normalized parameter FD (F is the frequency) is among multiples of the half velocities of either longitudinal or shear waves in the sample. A model is proposed to explain these minima as destructive interference due to the higher order modes of leaky Lamb waves with very large phase velocities.
ASJC Scopus subject areas
- Physics and Astronomy(all)