Electromagnetic nondestructive evaluation with simple HTS SQUIDs: measurements and modelling

Morgan, L.N.C.; Carr, C.; Cochran, A.; McKirdy, David M.; Donaldson, G.B.

doi:10.1109/77.403254

Cited by 17 publications

(8 citation statements)

References 3 publications

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“…For a single flaw such as a narrow rectangular slit and a source such as the 63 mm diameter double-D induction coil described later, the solution takes several hours. Given this onerous overhead, we have limited our FEM studies to the effects of different coil geometries, observed via current flow amplitudes in the specimen, and of different induction frequencies, in the latter case obtaining results which corresponded well with experimental measurements [11].…”

Section: Modelingmentioning

confidence: 54%

Advances in the Theory and Practice of Squid NDE

Cochran

Donaldson

Carr

et al. 1996

Review of Progress in Quantitative Nondestructive Evaluation

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Section: Modelingmentioning

confidence: 54%

Advances in the Theory and Practice of Squid NDE

Cochran

Donaldson

Carr

et al. 1996

Review of Progress in Quantitative Nondestructive Evaluation

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“…But in FEM based analysis, the number of finite elements for modelling increases remarkably as the size of the flaw becomes narrow and its shape becomes complex, [5], [6]. Therefore, it is difficult to make an accurate finite element model for such flaws and a large amount of computer resources is also necessary to compute the Eddy current distributions [6], [7]. Accordingly the accurate 3D simulation of the whole system as a single problem is not practical.…”

Section: Numerical Finite Element Simulationmentioning

confidence: 99%

FEM enhanced signal processing approach for pattern recognition in the SQUID based NDE system

Sarreshtedari

Jahed

Hosseni

et al. 2010

J. Phys.: Conf. Ser.

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Abstract. An efficient Non-Destructive Evaluation algorithm has been developed in order to extract the required information for pattern recognition of defects in the conductive samples. Using high-Tc gradiometer RF-SQUIDs in unshielded environments and incorporating an automated two dimensional non-magnetic scanning robot, samples with different intentional defects have been tested. We have used a developed noise cancellation approach for the improvement of the effectiveness of the used inverse-problem technique. In this approach we have used a well examined Finite Element Method (FEM) to apply a noise reduction filtering on the obtained raw magnetic image data before incorporating the signal processing analysis. By applying this noise cancellation filter and incorporating three different signal processing algorithms and comparing the results of the predicted images by the pattern of the intentionally made defects, we have investigated the ability of these methods for pattern recognition of unknown defects.

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“…A recent adaptation of coil inducers is the 'double-D' excitation coil. This design is used at Strathclyde [65][66][67] and (a very similar design) KFA [68,69] for high-T c SQUID gradiometric systems. The excitation coil has the same layout as the double-D pick-up coil at the centre of figure 12.…”

Section: The Current Induction Techniquementioning

confidence: 99%

“…The SQUID response above the surface of a fibreglass-clad aluminium pressure vessel scanned with a high-T c electronic gradiometer and double-D excitation coil (Strathclyde design). This section of the vessel has a fatigue crack in the aluminium which perturbs the field greatly in the vicinity of (150,150). Notice that although the fatigue crack is oriented along the longitudinal scan direction and is very narrow, the perturbation around the circumference has the same dimension as the inducing coil.…”

Section: The Current Induction Techniquementioning

confidence: 99%

SQUIDs for nondestructive evaluation

Jenks

Sadeghi

Wikswo

1997

J. Phys. D: Appl. Phys.

141

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We attempt a comprehensive review of all published research in nondestructive evaluation (NDE) performed with the superconducting quantum interference device (SQUID) magnetometer since the first work was reported in the mid-1980s. The SQUID is the most sensitive detector of magnetic flux known. The energy sensitivity of the SQUID may make it the most sensitive detector of any kind. The research on SQUIDs for NDE is based on the promise of that sensitivity and on the various other desirable properties developed for SQUID instrumentation in biomagnetism and other fields. The sensitivity of SQUID instruments down to very low frequencies allows them to function as eddy-current sensors with unparalleled depth resolution, and to image the static magnetization of paramagnetic materials and the flow of near-dc corrosion currents. The wide dynamic range of the SQUID makes it possible to image defects in steel structures and to measure the magnetomechanical behaviour of ferromagnetic materials with high sensitivity. In the last decade SQUID instrumentation designed specifically for NDE has appeared and improved the spatial resolution of most work to roughly 1 mm, with promise of another order of magnitude improvement within the next five years. Algorithms for flaw detection and image deconvolution have begun to flourish. With many talented, industrious people in the field, the future of SQUID NDE looks bright, provided the crucial first niche can be found.

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Electromagnetic nondestructive evaluation with simple HTS SQUIDs: measurements and modelling

Cited by 17 publications

References 3 publications

Advances in the Theory and Practice of Squid NDE

Advances in the Theory and Practice of Squid NDE

FEM enhanced signal processing approach for pattern recognition in the SQUID based NDE system

SQUIDs for nondestructive evaluation

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