Relation between mechanical microhardness and impedance variations in eddy current testing

Zergoug, M.; Lebaili, S.; Boudjellal, H.; Benchaala, A.

doi:10.1016/j.ndteint.2003.09.002

Cited by 65 publications

(37 citation statements)

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“…ECT is also used to evaluate defects in various other environments and configurations [14]. These include flaws in steam generator tubes [18][19][20][21][22][23], fatigue cracks [24][25][26], corrosion [27][28][29][30][31][32][33], material microstructure near welds [34], and estimation of pearlite percentages in plain carbon steels [35,36] and in cast irons [37]. High density eddy current C-Scan data has also been used for the analysis of bolt hole eddy current [38] and estimation of micro-crack lengths [39].…”

Section: Introductionmentioning

confidence: 99%

Surface Profiling and Core Evaluation of Aluminum Honeycomb Sandwich Aircraft Panels Using Multi-Frequency Eddy Current Testing

Reyno¹,

Underhill²,

Krause³

et al. 2017

Preprint

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Surface damage on honeycomb aircraft panels is often measured manually, and is therefore subject to variation based on inspection personnel. Eddy current testing (ECT) is sensitive to variations in probe-to-specimen spacing, or lift-off, and is thus promising for high resolution profiling of surface damage on aluminum panels. Lower frequency testing also allows inspection through the face sheet, an advantage over optical 3D scanning methods. This paper presents results from the ECT inspection of surface damage on an approximately flat aluminum honeycomb aircraft panel, and compares the measurements to those taken using optical 3D scanning technology. An ECT C-Scan of the dented panel surface was obtained by attaching the probe to a robotic scanning apparatus. Data was taken simultaneously at four frequencies of 25, 100, 400 and 1,600 kHz. A reference surface was then defined that approximated the original, undamaged panel surface, which also compensated for the effects of specimen tilt and thermal drift within the ECT instrument. Data was converted to lift-off using height calibration curves developed for each probe frequency. A damage region of 22,550 mm 2 area with dents ranging in depth from 0.13-1.01 mm was analyzed. The method was accurate at 1,600 kHz to within 0.05 mm (2σ) when compared with 231 measurements taken via optical 3D scanning. Testing at 25 kHz revealed a 3.2 mm cell size within the honeycomb core, which was confirmed via destructive evaluation. As a result, ECT demonstrates potential for implementation as a method for rapid in-field aircraft panel surface damage assessment.

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Section: Introductionmentioning

confidence: 99%

Surface Profiling and Core Evaluation of Aluminum Honeycomb Sandwich Aircraft Panels Using Multi-Frequency Eddy Current Testing

Reyno¹,

Underhill²,

Krause³

et al. 2017

Preprint

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“…The coil excitation frequency f permits the adjustment of the Metals 2017, 7, 385 3 of 12 penetration depth δ, which is proportional to f −0.5 , according to the skin effect [27,28]. The acquired impedance of the coil Z coil (x, σ, µ, f ) is mainly related to the electrical conductivity σ, to the magnetic permeability µ, to the lift-off x, and to the applied and the residual stresses of the steel sample that slightly influence on σ and µ ( Figure 2) [2,28].…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…Eddy current testing has been one of the most popular NDT techniques, and has been widely implemented as an alternative to metallography [1] and indentation hardness tests [2]. Eddy current testing is based on Faraday's electromagnetic induction law, which was proposed in 1831, and on Hughes' experiments, which were performed in 1879.…”

Section: Introductionmentioning

confidence: 99%

RBF-Neural Network Applied to the Quality Classification of Tempered 100Cr6 Steel Cams by the Multi-Frequency Nondestructive Eddy Current Testing

Martínez-Martínez

García-Martín

Gómez-Gil

2017

Metals

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This article proposes a Radial Basis Function Artificial Neural Network (RBF-ANN) to classify tempered steel cams as correctly or incorrectly treated pieces by using multi-frequency nondestructive eddy current testing. Impedances at five frequencies between 10 kHz and 300 kHz were employed to perform the binary sorting. The ANalysis Of VAriance (ANOVA) test was employed to check the significance of the differences between the impedance samples for the two classification groups. Afterwards, eleven classifiers were implemented and compared with one RBF-ANN classifier: ten linear discriminant analysis classifiers and one Euclidean distance classifier. When employing the proposed RBF-ANN, the best performance was achieved with a precision of 95% and an area under the Receiver Operating Characteristic (ROC) curve of 0.98. The obtained results suggest RBF-ANN classifiers processing multi-frequency impedance data could be employed to classify tempered steel DIN 100Cr6 cams with a better performance than other classical classifiers.

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“…The material microstructure at the heat affected zones near welds was characterized using Eddy current technique [67]. The estimation of pearlite percentages in low to high plain carbon steels was studied using Eddy current technique in [68,69] and Ghanei et al [70] estimated the pearlite percentage in ductile cast irons for prediction of mechanical properties in cast irons.…”

Section: Other Applicationsmentioning

confidence: 99%

Defect Characterization Based on Eddy Current Technique: Technical Review

Ghoni

Dollah

Sulaiman

et al. 2014

Advances in Mechanical Engineering

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Eddy current testing is widely used for nondestructive evaluation of metallic structures in characterizing numerous types of defects occurring in various locations. It offers remarkable advantages over other nondestructive techniques because of its ease of implementation. This paper presents a technical review of Eddy current technique in various scope of defect detection. The first part presents Eddy current evaluation on various defects location and orientation such as steam generator tubes, stress crack corrosion, and fatigue cracks. The next section analyzes the use of pulsed Eddy current and pulsed Eddy current thermography as an alternative method for monitoring the growth of cracks with the aid of computational techniques for postsignal analysis.

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Relation between mechanical microhardness and impedance variations in eddy current testing

Cited by 65 publications

References 0 publications

Surface Profiling and Core Evaluation of Aluminum Honeycomb Sandwich Aircraft Panels Using Multi-Frequency Eddy Current Testing

Surface Profiling and Core Evaluation of Aluminum Honeycomb Sandwich Aircraft Panels Using Multi-Frequency Eddy Current Testing

RBF-Neural Network Applied to the Quality Classification of Tempered 100Cr6 Steel Cams by the Multi-Frequency Nondestructive Eddy Current Testing

Defect Characterization Based on Eddy Current Technique: Technical Review

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