Pulsed eddy current detection of cracks in F/A-18 inner wing spar at large lift-off using modified principal component analysis

Horan, Peter; Underhil, Ross; Krause, Thomas W.

doi:10.3233/jae-141842

Cited by 7 publications

(4 citation statements)

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“…As demonstrated in the subsection above, the first two eigenvectors are the most associated with the sample thickness, while the third and fourth eigenvectors can be associated with the cladding thickness. This solution, however, is still limited as the third eigenvector still accounts for the sample thickness, owing to the second peak of the eigenvector at 0.025 s. Motivated by this, the solution can be rotated, so that the variances are redistributed among the rotated components, as was done in previous work [19]. Rotation in PCA is normally done so that each eigenvector can be associated with at most one factor only.…”

Section: Pca Rotationmentioning

confidence: 99%

“…Another example that is close to the work carried out here is the application of PCA to separate the signal effects of tubes degradation with those of ferromagnetic support, as reported by Buck et al [17], owing to the large difference in the "relaxation times" for eddy current diffusion in the tube compared to those of the ferromagnetic support. Similar effort has also been carried out to detect loose parts in steam generator [18] and cracks in inner wing spar of an F/A-18 Hornet aircraft [19].…”

Section: Introductionmentioning

confidence: 99%

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Decoupling the Influence of Wall Thinning and Cladding Thickness Variations in Pulsed Eddy Current Using Principal Component Analysis

et al. 2021

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Corrosion may develop and grow on steel pipes under layers of insulation and cladding. Inspection of the pipes through these protective layers is of paramount importance. Pulsed eddy current (PEC) is a primary non-destructive testing (NDT) technique candidate for this type of inspection as it requires no contact with the inspection material. To overcome the variability in PEC signals due to variations in the cladding thickness, a large measurement set is analysed in this paper using principal component analysis (PCA). The PCA approach decomposes the signal set into a number of uncorrelated variables that explain the maximum amount of the variance in the data set, in which, in this respect, efficiently separate the influences contributed by the difference in the material properties of cladding and pipe wall. The feasibility of using PCA to quantify simulated steel pipe wall independent of confounding cladding thickness variations is investigated. It is found that, with sufficient amount of data, the approach can effectively separate the influences contributed by the wall thickness variations from the cladding thickness variations.

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Section: Pca Rotationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Decoupling the Influence of Wall Thinning and Cladding Thickness Variations in Pulsed Eddy Current Using Principal Component Analysis

et al. 2021

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“…PCA/ICA‐based method is an obvious improvement [105]. PEC, generated by a probe design that utilises the ferrous fastener as a flux conduit, are demonstrated to have capability of detecting simulated cracks within the spar with the wing skin present.…”

Section: Crack Defect Classificationmentioning

confidence: 99%

Review on system development in eddy current testing and technique for defect classification and characterization

Ali

Abdalla

Rifai

et al. 2017

IET Circuits, Devices & Systems

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Eddy current testing (ECT) is one of the non-destructive evaluation techniques widely used, especially in oil and gas industries. It characterized noisy data to the less-than-perfect detection and as an indication of serious false alarm problem. However, not many researchers have described in detail the intelligent ECT crack detection system. This paper introduces a review of ECT technique and factors that affect the signal fundamental according to the hardware and software development. First, describe the magnetic excitation resources including the sinusoidal and pulse exciting signal. Second, outlines explanation about the ECT probe. The explanations are more about the probes development for air core probe and giant magnetoresistance probe. Third, there is discussion on ECT circuit that used including ECT system, ECT rotating magnetic field and application measurement for optimal control parameters. The defect in characterizations and measurement are discussed on the fourth part of this paper. The fourth part discusses the ECT lift-off compensation including the lift-off and application of intelligent technique in ECT. The limitations of lift-off for coil probe and compensation techniques also discussed in this part. Finally, a comprehensive review of previous studies on the application of intelligent ECT crack detection in nondestructive ECT is presented.

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“…Stored eigenvectors and discriminant functions from calibration measurements then allow for nearinstantaneous (∼1ms) real time crack discrimination of samples of unknown condition. This permits for inspection times on the order of 5 hours for the two wings on a single aircraft, thereby reducing inspection times by up to a factor of 10 when compared with radiographic inspection [17].…”

mentioning

confidence: 98%

Real Time Pulsed Eddy Current Detection of Cracks in F/A-18 Inner Wing Spar Using Discriminant Separation of Modified Principal Components Analysis Scores

2014

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The aluminum inner wing spars of F/A-18 Hornet aircraft may undergo stress corrosion cracking along the spar between the fasteners that secure carbon-fiber/epoxy composite skin to the wing. Inspection of the spar through the wing skin is required to avoid wing disassembly. The thickness of the skin varies between 9 and 21 mm (0.36-0.83 in) and fasteners may be either titanium or ferrous. Pulsed eddy currents (PECs), generated by a probe centered over the fastener, demonstrate the capability of detecting simulated cracks within spars with the wing skin present. Comparison of signals from separate pick-up coils, mounted to either side of the excitation coil, is used to detect differences in induced eddy current fields, which arise in the presence of cracks. To overcome variability in PEC signal response due to variation in: 1) skin thickness; 2) fastener material and size; and 3) centering over fasteners, a large calibration data set is acquired. Multidimensional scores from a modified principal components analysis (PCA) of the data are reduced to 1-D using a discriminant analysis method. Under inspection conditions, calibration PCA scores combined with discriminant analysis permit rapid real time go/no-go PEC detection of cracks in F/A-18 inner wing spar.

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Pulsed eddy current detection of cracks in F/A-18 inner wing spar at large lift-off using modified principal component analysis

Cited by 7 publications

References 0 publications

Decoupling the Influence of Wall Thinning and Cladding Thickness Variations in Pulsed Eddy Current Using Principal Component Analysis

Decoupling the Influence of Wall Thinning and Cladding Thickness Variations in Pulsed Eddy Current Using Principal Component Analysis

Review on system development in eddy current testing and technique for defect classification and characterization

Real Time Pulsed Eddy Current Detection of Cracks in F/A-18 Inner Wing Spar Using Discriminant Separation of Modified Principal Components Analysis Scores

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