Application of a new theoretical treatment to an old problem; sinusoidal pressure release boundary scattering

McCammon, Diana F.; McDaniel, Suzanne T.

doi:10.1121/1.392580

Cited by 23 publications

(8 citation statements)

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“…Without alteration, phenomena such as surface self-shadowing and diffraction are also generally not well modeled using such approaches, limiting the levels of surface roughness which can be investigated. Information regarding the validity of the Kirchhoff approximation can be found in [17] and [18].…”

Section: B Rough Surface Scattering Modelsmentioning

confidence: 99%

Scattering of near normal incidence SH waves by sinusoidal and rough surfaces in 3-D: Comparison to the scalar wave approximation

Jarvis

Cegla

2014

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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The challenge of accurately simulating how incident scalar waves interact with rough boundaries has made it an important area of research within many scientific disciplines. Conventional methods, which in the majority of cases focus only on scattering in two dimensions, often suffer from long simulation times or reduced accuracy, neglecting phenomena such as multiple scattering and surface self-shadowing. A simulation based on the scalar wave distributed point source method (DPSM) is presented as an alternative which is computationally more efficient than fully meshed numerical methods while obtaining greater accuracy than approximate analytical techniques. Comparison is made to simulated results obtained using the finite element method for a sinusoidally periodic surface where scattering only occurs in two dimensions, showing very good agreement (<0.2 dB). In addition to two-dimensional scattering, comparison to experimental results is also carried out for scattering in three dimensions when the surface has a Gaussian roughness distribution. Results indicate that for two-dimensional scattering and for rough surfaces with a correlation length equal to the incident wavelength (λ) and a root mean square height less than 0.2λ, the scalar wave approximation predicts reflected pulse shape change and envelope amplitudes generally to within 1 dB. Comparison between transducers within a three-element array also illustrate the sensitivity pulse amplitude can have to sensor position above a rough surface, differing by as much as 17 dB with a positional change of just 1.25λ.

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Section: B Rough Surface Scattering Modelsmentioning

confidence: 99%

Scattering of near normal incidence SH waves by sinusoidal and rough surfaces in 3-D: Comparison to the scalar wave approximation

Jarvis

Cegla

2014

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…Scattering from a large-amplitude sinusoidal surface whose wavelength is approaching that of the incident radiation is of interest in its own right. The subject has been explored extensively and continues to be active [McCammon and McDaniel, 1985;Jordan and Lang, 1979]. As with rough surface scatter in general, however, grazing incidence has been given little attention.…”

Section: Plane Surfacesmentioning

confidence: 99%

Application of beam simulation to scattering at low grazing angles: 1. Methodology and validation

Ngo¹,

Rino²

1994

Radio Science

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Numerical simulations of rough surface scattering at near‐grazing incidence require very large surfaces (≳500λ). Conventional methods of exact solutions require the inversion of a very large matrix, which can exceed the memory and speed capabilities of even modern supercomputers. The beam simulation method proposed by Saillard and Maystre circumvents this problem by decomposing the large incident beam into narrower subbeams and then synthesizing the large beam by coherent superposition. The radius of these narrower subbeams is determined by the local interaction distance on the surface, which is found to increase with incidence angle, ultimately forcing a single beam in the limit of strict grazing incidence. This paper demonstrates that this technique gives essentially the same results as can be obtained by the method of moments and can handle surfaces as large as 1000λ for grazing incidence angle as low as 10°.

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“…Periodic surfaces [5] or superposition of sinusoidal surfaces [6] seems to be a reasonable initial option and these ideas have been used to generate rough surfaces for simulations. They are relatively easy to create and the methods provide good knowledge of the characterization of the reflections from rough surfaces in general.…”

Section: Introductionmentioning

confidence: 99%

“…Scattering from rough surfaces has been investigated in many research areas including NDE [for example, [1][2][3][4][5][6]. While the reflection from a smooth crack has strong amplitude at specular angles, the amplitude from a rough crack tends to be lower than that, since the reflected energy is dissipated to the other directions depending on the roughness of the crack, and thus the amplitude increases in non-specular reflection.…”

Section: Introductionmentioning

confidence: 99%

Rough surface reconstruction for ultrasonic NDE simulation

Skelton¹,

Shi²,

Lowe³

2014

AIP Conference Proceedings

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The reflection of ultrasound from rough surfaces is an important topic for the NDE of safety-critical components, such as pressure-containing components in power stations. The specular reflection from a rough surface of a defect is normally lower than it would be from a flat surface, so it is typical to apply a safety factor in order that justification cases for inspection planning are conservative. The study of the statistics of the rough surfaces that might be expected in candidate defects according to materials and loading, and the reflections from them, can be useful to develop arguments for realistic safety factors. This paper presents a study of real rough crack surfaces that are representative of the potential defects in pressure-containing power plant. Two-dimensional (area) values of the height of the roughness have been measured and their statistics analysed. Then a means to reconstruct model cases with similar statistics, so as to enable the creation of multiple realistic realizations of the surfaces, has been investigated, using random field theory. Rough surfaces are reconstructed, based on a real surface, and results for these two-dimensional descriptions of the original surface have been compared with those from the conventional model based on a one-dimensional correlation coefficient function. In addition, ultrasonic reflections from them are simulated using a finite element method.

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Application of a new theoretical treatment to an old problem; sinusoidal pressure release boundary scattering

Cited by 23 publications

References 0 publications

Scattering of near normal incidence SH waves by sinusoidal and rough surfaces in 3-D: Comparison to the scalar wave approximation

Scattering of near normal incidence SH waves by sinusoidal and rough surfaces in 3-D: Comparison to the scalar wave approximation

Application of beam simulation to scattering at low grazing angles: 1. Methodology and validation

Rough surface reconstruction for ultrasonic NDE simulation

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