Ultrasonic probe modeling and nondestructive crack detection

Boström, Anders E; Wirdelius, Håkan

doi:10.1121/1.411850

Cited by 66 publications

(46 citation statements)

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“…Boström and Wirdelius 23 have studied an additional aspect of the problem by calculating the field of an unfocused, but finite-sized transducer used as transmitter and receiver for ultrasonic inspection. In their approach the scatterer's response is represented by a T matrix which, for a spherical scatterer, can be calculated by the separation of variables method used in the present study.…”

Section: Introductionmentioning

confidence: 99%

Elastic wave scattering by shelled spherical scatterers in a focused field

Mittleman

Thompson

Han

1996

The Journal of the Acoustical Society of America

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Embrittlement of many important metal alloys has been related to the accumulation of undesirable materials at grain boundaries, a condition which may be detectable through measurement of ultrasonic scattering from the material's microstructure. Grains with decorated grain boundaries are modeled as shelled microspheres embedded in an isotropic elastic host, and a practical means of predicting scattering from these particles is developed. The incident field often used for measuring backscattered grain noise is focused; both plane and focused incident fields are treated. Theoretical predictions of scattering from isolated scatterers are compared with experimental measurements on metal microspheres embedded in plastic to validate the computational procedure, then predictions of scattering from similar spherical structures embedded in a metal host are presented. In the former case theoretical predictions are found consistent with observations, although differences between shelled and nonshelled scatterers are obscured by the great contrast between host and scatterer. In the latter case, where host and core are quite similar, even thin shells can produce scattering readily distinguishable from the weak scattering in polycrystals that may be due to locally inhomogeneous properties. Results of this study can be used to calculate a backscattering coefficient for calculations of grain noise in metals containing, or composed of, numerous shelled scatterers. Embrittlement of many important metal alloys has been related to the accumulation of undesirable materials at grain boundaries, a condition which may be detectable through measurement of ultrasonic scattering from the material's microstructure. Grains with decorated grain boundaries are modeled as shelled microspheres embedded in an isotropic elastic host, and a practical means of predicting scattering from these particles is developed. The incident field often used for measuring backscattered grain noise is focused; both plane and focused incident fields are treated. Theoretical predictions of scattering from isolated scatterers are compared with experimental measurements on metal microspheres embedded in plastic to validate the computational procedure, then predictions of scattering from similar spherical structures embedded in a metal host are presented. In the former case theoretical predictions are found consistent with observations, although differences between shelled and nonshelled scatterers are obscured by the great contrast between host and scatterer. In the latter case, where host and core are quite similar, even thin shells can produce scattering readily distinguishable from the weak scattering in polycrystals that may be due to locally inhomogeneous properties. Results of this study can be used to calculate a backscattering coefficient for calculations of grain noise in metals containing, or composed of, numerous shelled scatterers.

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Section: Introductionmentioning

confidence: 99%

Elastic wave scattering by shelled spherical scatterers in a focused field

Mittleman

Thompson

Han

1996

The Journal of the Acoustical Society of America

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“…For this reason a transducer model developed in [Boström and Wirdelius 1995] is employed. In this model the stress at the interface between the transducer and the component is prescribed.…”

Section: The Incoming Fieldmentioning

confidence: 99%

“…Here (x t , y t , d 1 ) are the coordinates of the transmitter, and the coefficients ξ n are given in [Boström and Wirdelius 1995] for various types of transmitters. The displacement field in a cladding without a crack is…”

Section: The Incoming Fieldmentioning

confidence: 99%

Wave scattering from a rectangular crack in an anisotropic cladding

Jansson¹

2011

J. Mech. Mater. Struct.

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Ultrasonic testing of a thick elastic plate with a crack in an anisotropic cladding is modeled analytically for a fully three-dimensional case. The model includes an ultrasonic transmitter and a receiver as well as wave scattering from a rectangular crack. The effect of a corrugated interface between the base component and the cladding is also taken into account. To solve the scattering problem the null field approach is employed to determine a Green's tensor for the same structure without a crack and the source point located in the cladding. Utilizing the Green's tensor an integral representation for the displacement field in the same structure with a crack and an incident field generated by an ultrasonic transducer may be derived. It is then straightforward to derive a hypersingular integral equation for the crack opening displacement, which can be used to determine the change in signal response due to the crack by Auld's reciprocity argument. Numerical results are given for a variety of cases illustrating the effects of size, position, and orientation of the crack and the properties of the corrugated interface. IntroductionUltrasonic nondestructive testing is frequently used to detect defects, e.g., in nuclear power plants. Even though the method has been in use for a considerable time and may be regarded as well-established, there is a need for modeling of the testing procedure. Such a model may be useful for planning of testing, for qualification of testing procedures, for interpretation of results, and for education purposes. Using a good mathematical model also has the benefit of being much cheaper than experimental methods, in particular when parameter studies are performed.In the nuclear power industry it is common to use claddings, i.e., layers of austenitic steel, to prevent or reduce corrosion. A cladding may be applied to a thick plate or a thick-walled pipe by a manual or automated welding process. As a result of the fabrication process the interface between the base material and the cladding usually becomes corrugated, which is likely to affect the propagation of ultrasonic waves. Furthermore, the cladding material is normally anisotropic, which will also complicate the interpretation of test results. Thus, a numerical model for the testing procedure may be useful for understanding of the influence of the cladding on the signal response. An overview of ultrasonic testing of clad components is given in [Hudgell 1994].Various wave propagation problems for a thick plate with a cladding with or without a crack have been studied previously. The 2D and 3D wave propagation problems for a structure without a crack have been investigated in [Krasnova et al. 2005;Krasnova 2005] The aim of this paper is to develop a fully three-dimensional analytical model for a thick plate with a rectangular crack of arbitrary orientation in a cladding. Both materials are allowed to be anisotropic without any restrictions on symmetry or orientation of the crystal axes. In the numerical examples, however, only the case of a...

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“…The model of the transmitting probe is similar to the one used by Boström and Wirdelius [5] to model a probe on a planar surface. The action of the probe is thus modelled as an applied traction as the boundary condition where the probe is located.…”

Section: Transmitting and Receiving Probesmentioning

confidence: 99%

“…Note that only the normal component (pressure) is taken as nonzero (although there is no difficulty to include also tangential components, see Boström and Wirdelius [5]), the other components and the traction on the inner surface of the pipe are zero. Here ζ is the half length of the probe in the axial direction, δ is the half width of the probe in the angular direction, and ϕ 0 is the probe position, see Fig.…”

Section: Transmitting and Receiving Probesmentioning

confidence: 99%

Modelling of Ultrasonic Bulk Wave Scattering by an Axial Crack in a Pipe

Rubenson

Boström

2017

J Nondestruct Eval

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Modelling of ultrasonic bulk wave scattering by an internal, infinitely long, axial crack in a thick-walled pipe is considered. The problem is formulated as a hypersingular integral equation for the crack-opening displacement (COD), the hypersingularity arises in the Green's tensor. The COD is expanded in Chebyshev functions which have the correct square-root singularity along the crack edges, thereby regularizing the integral equation. To discretize the integral equation it is likewise projected onto the same Chebyshev functions. A model of an ultrasonic rectangular vertically polarized shear wave contact probe is developed, and the signal response is calculated using a reciprocity argument. Some numerical examples demonstrate the possible application of the method, in particular investigating the importance of the pipe curvature.

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Ultrasonic probe modeling and nondestructive crack detection

Cited by 66 publications

References 0 publications

Elastic wave scattering by shelled spherical scatterers in a focused field

Elastic wave scattering by shelled spherical scatterers in a focused field

Wave scattering from a rectangular crack in an anisotropic cladding

Modelling of Ultrasonic Bulk Wave Scattering by an Axial Crack in a Pipe

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