Regularized inversion of a distributed point source model for the reconstruction of defects in eddy current imaging

Bausson, S.; Thomas, Vincent; Joubert, Pierre-Yves; Blanc‐Féraud, Laure; Darbon, Jérôme; Aubert, Gilles

doi:10.1108/03321641111168093

Cited by 4 publications

(6 citation statements)

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“…The results are gathered in Table 1. One can note that in the considered frequency range, all the defects are correctly sensed (the PSNR being always higher than 36 dB), which gives good prospects for the solving of the inverse problem required for the accurate characterization of defects [17]. Furthermore, the evolution of the maximum value of the defect signatures as a function of the defect depth is plotted for 3 different frequencies in Figure 8.…”

Section: First Experimental Resultsmentioning

confidence: 84%

“…Nevertheless, these preliminary results validate the experimental feasibility of the EC imaging probe. The imaging probe is designed to operate in a large frequency bandwidth, since previous works have shown that enhanced defect reconstruction results were obtained starting from multifrequency EC data [17]. Considering the penetration depth  of the EC within the material, which may be approximated by [21]: (1) and considering the larger defect to be imaged (D 3 , 1 mm deep), one can conclude that frequencies ranging from less than 15 kHz up to hundreds of kHz should be used to provide varied EC information relative to these surface-breaking defects.…”

Section: First Experimental Resultsmentioning

confidence: 99%

“…The design of the probe itself, including the study of the influence of the sensing element technology, was carried out by the means finite element computations and presented in [16]. In paper [17], the authors have proposed an inversion algorithm, developed in a total variation regularized optimization framework, able to carry out the three-dimensional reconstruction of surface breaking defects in the bore-hole, starting from EC data simulated in a large frequency bandwidth. In this paper, we report on the experimental validation and characterization of such an EC array probe dedicated to bore-hole imaging, with multi-frequency reconstruction of defects in view.…”

Section: Introductionmentioning

confidence: 99%

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Experimental validation of an eddy current probe dedicated to the multi-frequency imaging of bore holes

Joubert

Vourch

Thomas

2012

Sensors and Actuators A: Physical

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This paper deals with the experimental characterization of an array probe dedicated to the eddy current imaging of sub-millimetric surface breaking defects appearing in bore holes of metallic parts. The probe is constituted of a large inducer generating an uniformly oriented EC flow within the inspected material, and a sensing array probe featuring bobbin coils to sense the radial component of the magnetic field resulting from the eddy currents / defects interactions within the wall of the bore hole. The probe was designed with accurate defect characterization in view, i.e. to provide multi-frequency and high spatial resolution images with a reduced acquisition time, so as to enhance the informative content of the acquired eddy current data. An experimental setup was build in order to validate the imaging performances of such a probe. A prototype featuring a large inducer and a single sensing coil which can be accurately positioned in the sensing area, has been developed in order to evaluate the sensing performances as well as to study the influence of the sensing array configuration on the imaging performances. The experimental results demonstrate a good sensing ability of the designed probe in the 10 kHz-800 kHz frequency range, with peak-signal-to-noise ratios higher than 36 dB at 10 kHz (and 62 dB at 800 kHz) for defects featuring dimensions as small as 0.4×0.2×0.2 mm 3. Furthermore, a staggered row arrangement of the sensing array was proposed so as to significantly reduce the error due to the sampling step resulting from the pickup coils geometry (from 35% to less than 9% in the worst case). The experimental evaluation of the probe provides promising prospects for the accurate characterization of defects, by means of advanced multifrequency signal processing algorithms.

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Section: First Experimental Resultsmentioning

confidence: 84%

Section: First Experimental Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Experimental validation of an eddy current probe dedicated to the multi-frequency imaging of bore holes

Joubert

Vourch

Thomas

2012

Sensors and Actuators A: Physical

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“…As a consequence, these two approaches cannot effectively identify girth weld defects. On the other hand, eddy current testing (ECT) technology is endowed with the advantages of high sensitivity, high precision and non-contact, and may be efficiently applied to automatic detection [9][10][11][12][13]. It has been widely used for the non-destructive testing of pipelines, especially for the detection of the girth weld defects in the inner surface [14,15].…”

Section: Introductionmentioning

confidence: 99%

Pipe Crack Recognition Based on Eddy Current NDT and 2D Impedance Characteristics

et al. 2019

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Girth weld cracking of long-distance oil and gas pipelines yields substantial harm to pipeline safety and may cause serious accidents. As of today, non-destructive testing has been one of the most common methods for predicting potential faults and ensuring safe operation. Classical pipeline non-destructive testing methods include magnetic flux leakage testing and the use of ultrasonic testing by electromagnetic acoustic transducers. However, they are incapable of identifying the defects in complex surfaces like girth welds. Magnetic flux leakage testing exhibits poor anti-interference abilities and low space resolution. Ultrasonic testing by electromagnetic acoustic transducers suffer from low conversion efficiency and poor signal quality. In order to overcome the disadvantages of conventional pipeline non-destructive testing methods, we propose an embedded eddy current testing system by leveraging image processing and neural networks. Hough transform and the contour extraction technique are employed to extract the characteristic features from the two-dimensional (2D) eddy current impedance image. Experiment results show that the system can effectively identify the girth weld defects, featuring an accuracy of up to 92%. The low power consumption and compactness of the proposed system makes it a great candidate for pipeline inner inspection.

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“…The main advantages of the DPSM are that it is a "mesh-free" method (only the source network have to be actually meshed) and that workspaces including objects of any geometry may be modeled using such ESD, with no theoretical limitations on the shape and on the number of objects [22], as long as the considered media are isotropic and homogeneous. As a result, the DPSM constitutes a computationally efficient 3D modeling tool, which features great versatility, as already demonstrated in electrostatic problems [23,24], in ultrasonic problems [25,26], as well as electromagnetic problems [27] or coupled techniques (ultrasonics and electromagnetics [28]) with good prospects for the solving of inverse problems in EC applications [29,30].…”

Section: Introductionmentioning

confidence: 99%

A Differential DPSM Based Modeling Applied to Eddy Current Imaging Problems

Boré¹,

Joubert²,

Placko³

2014

PIER

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Abstract-This paper deals with an innovative implementation of a semi-analytical modeling method, called the Distributed Points Source Method (DPSM), in the case of an eddy current problem. The DPSM has already shown great potentialities for the versatile and computationally efficient modeling of complex electrostatic, electromagnetic or ultrasonic problems. In this paper, we report a new implementation of the DPSM, called differential DPSM, which shows interesting prospects for the modeling of complex eddy current problems such as met in the non-destructive imaging of metallic parts. In this paper, the used eddy current imaging device is firstly presented. It is composed of an eddy current (EC) inducer and a magneto optical set-up used to translate the magnetic field distribution appearing at the surface of the imaged part, into a recordable optical image. In this study, the device is implemented for the time-harmonics (900 Hz) imaging of a two-layer aluminum based assembly, featuring surfacebreaking and buried defects. Then, the basics of the time-harmonics DPSM modeling are recalled, and the differential approach is presented. It is implemented for the modeling of the interactions of the eddy current imaging device with the considered flawed assembly in the same operating conditions as the experimental implementation. The comparison between experimental and computed data obtained for millimetric surface and buried defects is presented in the form of complex magnetic cartographies and Lissajous plots. The obtained results show good agreement and open the way to the modeling of complex EC problems. Furthermore, the low computational complexity of the differential DPSM modeling makes it promising for solving EC inverse problems.

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Regularized inversion of a distributed point source model for the reconstruction of defects in eddy current imaging

Cited by 4 publications

References 10 publications

Experimental validation of an eddy current probe dedicated to the multi-frequency imaging of bore holes

Experimental validation of an eddy current probe dedicated to the multi-frequency imaging of bore holes

Pipe Crack Recognition Based on Eddy Current NDT and 2D Impedance Characteristics

A Differential DPSM Based Modeling Applied to Eddy Current Imaging Problems

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