Diffraction of ultrasonic waves from periodically rough liquid–solid surface

Abstract

Theoretical and experimental results concerning diffraction of ultrasonic waves on periodic liquid–elastic solid interfaces are presented. A general system of linear equations is established and solved numerically for triangular surfaces. Theoretical results are in good agreement with measurements obtained by a broadband pulse-echo system in the region where the wavelength is of the same order of magnitude as the period and much greater than the depth of the grating. In the spectrum of the reflection coefficient frequency minima are identified as the surface waves excited along the periodic surface.

Diffraction of homogeneous and inhomogeneous plane waves on a doubly corrugated liquid/solid interface

“…The one in the y direction for k n y is of course similar. For the case of a singly corrugated surface, expression (13) has been used before [6][7][8]16,17] and was experimentally verified, but it had never been theoretically proved up to now that this extension of the famous grating equation for plane waves [9,10,[12][13][14][15] is also valid for inhomogeneous waves.…”

“…This method has only been performed until now on singly corrugated surfaces, where it has been experimentally verified for incident homogeneous plane waves [9,15] as well as for incident inhomogeneous plane waves [8]. Actually, the limitations of the method are discussed in [6][7][8][9][10][12][13][14][15][16][17] and in this paper we limit the discussion to examples where the method is valid, i.e. where the considered wavelengths meet the required Lippmann conditions.…”

“…The current paper follows the method of Claeys et al [10,15] and Mampaert et al [9,[12][13][14] for incident homogeneous plane waves (i.e. the Rayleigh decomposition) and the extension by Briers et al [6][7][8]16,17] for inhomogeneous plane waves.…”

Evaluation of the height of internal periodic triangular surfaces by ultrasonic backscatter

“…The geometrical features of periodic surfaces can be immediately evaluated by using the corresponding diffracted modes of diffraction grating theory (Blessing et al, 1993). The sharp discontinuities or valleys in the frequency spectra as in diffraction grating in optics (Wood, 1902) have been used to identify the periodic profile parameters as reported by Claeys et al (1983). Moreover, both of the diffraction effects, Wood anomalies and Scholte-Stoneley waves, generated on periodically corrugated surfaces wave are relevant for surface defects detection by ultrasonic NDE (DeBilly et al, 1980;Jungman et al, 1982;Loewen and Povov, 1997;Mampaert and Leroy, 1988).…”

Ultrasonic evaluation of the pitch of periodically rough surfaces from back side

“…Wood anomalies (Wood, 1902) have been used to determine geometric parameters of a periodic surface. These appeared as sharp discontinuities or valleys in the frequency spectra as diffracted phenomena found in optics as well (Claeys, 1983). The Rayleigh-Fourier method has successfully been used to theoretically predict diffraction effects including Wood anomalies and Scholte-Stoneley wave generation on periodically corrugated surfaces (Jungman, 1982;.…”