Demonstration of model-based inversion of electromagnetic signals for crack characterization

Shell, Eric B.; Aldrin, John C.; Sabbagh, Harold A.; Sabbagh, Elias H.; Murphy, R. Kim; Mazdiyasni, Siamack; Lindgren, Eric A.

doi:10.1063/1.4914645

Cited by 17 publications

(11 citation statements)

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“…At present, best-practice typically involves using the eddy current response amplitude together with an empirically determined POD relationship to size cracks. While this is an accepted method, the underlying assumption of a uniform aspect ratio among cracks in both POD specimens and in-service parts is not always satisfied, leading to a reduction in the accuracy of predicted flaw dimensions [2]. Further, variations in probe characteristics, such as coil rotation and offset, can cause additional uncertainty in predicted dimensions [2].…”

Section: Introductionmentioning

confidence: 99%

“…While this is an accepted method, the underlying assumption of a uniform aspect ratio among cracks in both POD specimens and in-service parts is not always satisfied, leading to a reduction in the accuracy of predicted flaw dimensions [2]. Further, variations in probe characteristics, such as coil rotation and offset, can cause additional uncertainty in predicted dimensions [2]. To better characterize flaws, recent computational modeling research has focused on developing inversion methods to obtain improved estimates of flaw length, depth, width, and orientation.…”

Section: Introductionmentioning

confidence: 99%

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Flaw characterization using inversion of eddy current response and the effect of filters and scan resolution

Oneida¹,

Shell²,

Aldrin³

et al. 2016

AIP Conference Proceedings

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Flaw characterization using inversion of eddy current response and the effect of filters and scan resolution

Oneida¹,

Shell²,

Aldrin³

et al. 2016

AIP Conference Proceedings

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“…For more information on the experimental test plan and model-based inversion technique, see ref. [2,[4][5][6][7].…”

Section: -2mentioning

confidence: 99%

“…This approach can be prone to error in the crack profile assumption and will be sensitive to varying part and test conditions. Prior work on model-based inverse methods with eddy current inspection have demonstrated the ability to size corrosion pits [2] and fatigue cracks in aircraft multilayer structure bolt holes [3] and surface-breaking cracks in propulsion components [4][5][6][7][8]. Over the years, one key challenge in transitioning inverse methods for sizing discontinuities in NDE applications is the lack of …”

Section: Introductionmentioning

confidence: 99%

Model-based inverse methods for sizing surface-breaking discontinuities with eddy current probe variability

Aldrin¹,

Shell

Oneida

et al. 2016

AIP Conference Proceedings

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Abstract. The objective of this work is to demonstrate and validate model-based inversion techniques to characterize length, depth, width and orientation of surface-breaking cracks using eddy current NDE under varying probe conditions. A series of parametric studies of probe characteristics are presented for a fixed set of well-characterized flaws with varying length, depth, opening width and orientation angle. Results show inversion performance differences between probes with the same design specifications. Inversion results were also evaluated for a probe that was selectively controlled for varying probe liftoff, varying tilt in two directions, and orientation. Certain levels of probe tilt and liftoff were found to degrade the performance of the inversion technique. By using a model calibration process that incorporates the matching probe calibration data, better inversion results can be achieved, to a limited degree. There is a need to more appropriately adapt the model through the calibration fit to compensate for varying probe tilt and liftoff. Results are presented for a model transform approach, evaluating scale and phase terms based on the best model fit with the calibration data. The results for certain severe cases of liftoff were improved using the transformed model; however, it does not address all probe conditions. Future work is proposed to use a full model-based transformation approach using more comprehensive meta-model representations.

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“…However, in spite of the results obtained in the aforementioned works, many practical problems remain to be addressed, most of them concerning inversion applications. Very recently, metamodels have been proposed as tools for fast propagation of uncertainties in the inversion scheme in order to provide simulated results closer to real inspection scenarios [5,6,7,8]. In the aforementioned works, crack characterization was based on numerical simulation of Eddy Current Testing (ECT) signals while inversion was performed on experimental data.…”

Section: Introductionmentioning

confidence: 99%

Assessing performance of flaw characterization methods through uncertainty propagation

Miorelli

Bourdais

Artusi

2018

AIP Conference Proceedings

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Abstract. In this work, we assess the inversion performance in terms of crack characterization and localization based on synthetic signals associated to ultrasonic and eddy current physics. More precisely, two different standard iterative inversion algorithms are used to minimize the discrepancy between measurements (i.e., the tested data) and simulations. Furthermore, in order to speed up the computational time and get rid of the computational burden often associated to iterative inversion algorithms, we replace the standard forward solver by a suitable metamodel fit on a database built offline. In a second step, we assess the inversion performance by adding uncertainties on a subset of the database parameters and then, through the metamodel, we propagate these uncertainties within the inversion procedure. The fast propagation of uncertainties enables efficiently evaluating the impact due to the lack of knowledge on some parameters employed to describe the inspection scenarios, which is a situation commonly encountered in the industrial NDE context.

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Demonstration of model-based inversion of electromagnetic signals for crack characterization

Cited by 17 publications

References 0 publications

Flaw characterization using inversion of eddy current response and the effect of filters and scan resolution

Flaw characterization using inversion of eddy current response and the effect of filters and scan resolution

Model-based inverse methods for sizing surface-breaking discontinuities with eddy current probe variability

Assessing performance of flaw characterization methods through uncertainty propagation

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