Test Bed for Quantitative NDE — Inversion Results

Addison, R. C.; Elsley, R. K.; Martin, Joe

doi:10.1007/978-1-4684-4262-5_29

Cited by 15 publications

(30 citation statements)

References 2 publications

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“…The subscript, h, is used here (instead of "e" for electronic noise) in order to create a distinction between the electronic noise associated with the measurement system response, n^(w), and the electronic noise associated with the flaw signal, ng(w (Addison et al 1982, CohenTenoudji et al 1984, Clark et al 1985b, Clark et al 1986, Koo 1988). …”

Section: Ill-posednessmentioning

confidence: 99%

“…Above f^^^, it is also assumed that the estimate determined in step 1 contains no useful information. In order to force the scattering amplitude estimate to zero at high frequencies, the estimate is multiplied by a cosine-squared window which is centered at zero frequency and decreases to zero at 25% above ^max (Addison et al 1982). The window for the system response shown in 44 Lee (1981) explicitly considered the impulse response estimation problem as an ill-posed problem.…”

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confidence: 99%

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A prior knowledge based optimal Wiener filtering approach to ultrasonic scattering amplitude estimation

Neal

Thompson

1989

The Journal of the Acoustical Society of America

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, "A prior knowledge based optimal Wiener filtering approach to ultrasonic scattering amplitude estimation " (1988). Retrospective Theses and Dissertations. 8877. http://lib.dr.iastate.edu/rtd/8877 INFORMATION TO USERSThe most advanced technology has been used to photo graph and reproduce this manuscript from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer.The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction.In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion.Oversize materials (e.g., maps, drawings, charts) are re produced by sectioning the original, beginning at the upper left-hand corner and continuing from left to right in equal sections with small overlaps. Each original is also photographed in one exposure and is included in reduced form at the back of the book. These are also available as one exposure on a standard 35mm slide or as a 17" x 23" black and white photographic print for an additional charge.Photographs included in the original manuscript have been reproduced xerographically in this copy. Higher quality 6" x 9" black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. Signature was redacted for privacy.Signature was redacted for privacy.Signature was redacted for privacy. The work reported here is associated with flaw characterization.This work is motivated from an engineering perspective by considering two fundamentally different approaches to life prediction that can be found in fatigue of materials and structures. In a simplistic sense, a "safe life"or "zero defects" fatigue life prediction approach (Coffin and Tiffany 1976) assumes that once a flaw is macroscopic, i.e., once a flaw has grown to a size which can be detected by NDE techniques, failure is imminent and the component must be taken out of service. With this approach, qualitative NDE indicating the presence or absence of a flaw provides sufficient information to determine if a component should be retired. An alternative approach, which is sometimes referred to as a "damage tolerance" approach, is based on a fracture mechanics methodology (Coffin and Tiffany 1976, Rolfe and Barsom 1977). With this approach, instead of assuming that all flawed components must be taken out of service, the 2 severity of the flaw is assessed and a more rational determination of the remaining life of the component is made. To implement this approach, quantitative flaw characterization is required. As a minimum...

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Section: Ill-posednessmentioning

confidence: 99%

mentioning

confidence: 99%

A prior knowledge based optimal Wiener filtering approach to ultrasonic scattering amplitude estimation

Neal

Thompson

1989

The Journal of the Acoustical Society of America

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“…Several methods have been proposed to obtain the Born diameter from the characteristic function (3), including dividing the area under the characteristic function by its peak value and multiplying the result by 2, i.e., Area under J(r) 2 Peak Value of J(r) (3) Franz-Gruber Model for Spherical Voids Another way to solve the transducer-selection problem of the BIT for void-like flaws is to insonify the flaw in question with short, high-frequency shear waves and relate the separation of the backscattered satellite pulse [S in Figure 3(b») from the reflected pulse [R in Figure 3(b») to its "approximate dimension" (5). ** Freedman (6) assumed the waveform received from a void-like flaw of convex-shape to be composed of several discrete pulses, each identical to the transmitted pulse.…”

Section: Born Model For Spherical Inclusionsmentioning

confidence: 99%

Development of a Quantitative Flaw Characterization Module — A Status Report

Gruber

Hendrix

Mueller

1984

Review of Progress in Quantitative Nondestructive Evaluation

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Ultrasonic waves returning from an internal bulk flaw to a wideband transducer contain information on several characteristics of this flaw. Measurements made with waves of different mode, dominant frequency, incidence angle, beamwidth, etc. are, therefore, necessary to solve the inverse problem for flaw composition, size, and orientation in an unambiguous manner.The plan for the development of a reliable and accurate volumetric-flaw characterization module encompasses three basic elements: a transducer selection protocol, a deconvolution algorithm, and the Born as well as the Franz-Gruber (satellite pulse) models for the interaction of weakly and strongly scattering internal bulk flaws, respectively. The flaw-diameter estimates obtained by applying the Born Inversion Technique (BIT) and the Satellite-Pulse Observation Technique (SPOT), based on the above models, to the results of ultrasonic backscattering experiments are compared in this paper with the nominal effective diameters of five spherical voids in a titanium-alloy specimen tested under blind conditions.

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“…In fact, it employs the same input data as the 1-D IBA and consequently also shares certain common limitations such as the sensitivity of the sizing results to the zero of time determination and the available bandwidth of the scattering data [3,4]. However, flaw sizing using the zeroes is simpler and more straightforward because the sizes are obtained directly from the frequencies where the zeroes occur.…”

mentioning

confidence: 99%

“…1. for the special case of a sperhical flaw with radius r, the shape factor reduces to y(q) = 4nr 3 (sinz -zcosz)/z 3 (3) with z = qr. (ki) and scattered (ks) wavevector and the tangent plane d1stance (re).…”

mentioning

confidence: 99%