Pulse-modulation eddy current inspection of subsurface corrosion in conductive structures

Li, Yong; Yan, Biao; Li, Da; Han, Jing; Li, Yili; Chen, Zhenmao

doi:10.1016/j.ndteint.2016.02.001

Cited by 41 publications

(16 citation statements)

References 19 publications

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“…A study on different excitation waveforms, namely square, half-sine and ramp, shows a favour for the square waveform [2]. A variable pulse width excitation has also been proposed [3], which was used in the inspection of subsurface corrosion in conductive structures [4]. Pulse width modulation, as illustrated in Fig.…”

Section: Excitation Signalsmentioning

confidence: 99%

“…Other examples of defect detection and characterization include flaws in the inner surface of pipe under insulation [87], outer corrosion on carbon steel pipes used in oil and gas industry [35], surface and sub-surface cracks and cavity detection in con-casting slabs (CCS) [56], subsurface corrosion in a plate [4], surface corrosion on coated mild steel S275 plates [48], [88], and various types of defect on steam generator support structures [59]. Detection of wall thinning in pipe structures has been included in the previous sub-section above.…”

Section: Detection and Characterization Of Defectsmentioning

confidence: 99%

See 1 more Smart Citation

Pulsed Eddy Current Non-destructive Testing and Evaluation: A Review

Sophian

Tian

Fan

2017

Chin. J. Mech. Eng.

199

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Pulsed eddy current (PEC) non-destructive testing and evaluation (NDT&E) has been around for some time and it is still attracting extensive attention from researchers around the globe, which can be witnessed through the reports reviewed in this paper. Thanks to its richness of spectral components, various applications of this technique have been proposed and reported in the literature covering both structural integrity inspection and material characterization in various industrial sectors. To support its development and for better understanding of the phenomena around the transient induced eddy currents, attempts for its modelling both analytically and numerically have been made by researchers around the world. This review is an attempt to capture the state-of-the-art development and applications of PEC, especially in the last 15 years and it is not intended to be exhaustive. Future challenges and opportunities for PEC NDT&E are also presented.

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Section: Excitation Signalsmentioning

confidence: 99%

Section: Detection and Characterization Of Defectsmentioning

confidence: 99%

Pulsed Eddy Current Non-destructive Testing and Evaluation: A Review

Sophian

Tian

Fan

2017

Chin. J. Mech. Eng.

199

View full text Add to dashboard Cite

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“…It is assumed that the length and width of the HMD area are considerably larger than the outer diameter of the excitation coil. Based on the analytical modeling [14,16], the GPEC signal concerning the z -direction gradient field of the z -component of net magnetic field is formulated as:

g_{z} (B_{z}) = \frac{\partial B_{z}}{\partial z} = \frac{μ_{0} N I false(t false)}{H (r_{2} - r_{1}) h^{2}} \otimes true \sum_{i = 1}^{\infty} J_{0} (a_{i} r) [e^{a_{i} z} - e^{- a_{i} false(z + 2 ρ false)} η_{i} false(t false)] [e^{- a_{i} z_{1}} - e^{- a_{i} z_{2}}] \frac{χ (a_{i} r_{1}, a_{i} r_{2})}{{[a_{i} J_{0} (a_{i} h)]}^{2}}

where,

\otimes

denotes convolution. H is the coil height, H = z 2 − z 1 .…”

Section: Field Formulation Of Gpec and Investigation Of Loimentioning

confidence: 99%

A Gradient-Field Pulsed Eddy Current Probe for Evaluation of Hidden Material Degradation in Conductive Structures Based on Lift-Off Invariance

Han

Abidin

et al. 2017

Sensors

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Coated conductive structures are widely adopted in such engineering fields as aerospace, nuclear energy, etc. The hostile and corrosive environment leaves in-service coated conductive structures vulnerable to Hidden Material Degradation (HMD) occurring under the protection coating. It is highly demanded that HMD can be non-intrusively assessed using non-destructive evaluation techniques. In light of the advantages of Gradient-field Pulsed Eddy Current technique (GPEC) over other non-destructive evaluation methods in corrosion evaluation, in this paper the GPEC probe for quantitative evaluation of HMD is intensively investigated. Closed-form expressions of GPEC responses to HMD are formulated via analytical modeling. The Lift-off Invariance (LOI) in GPEC signals, which makes the HMD evaluation immune to the variation in thickness of the protection coating, is introduced and analyzed through simulations involving HMD with variable depths and conductivities. A fast inverse method employing magnitude and time of the LOI point in GPEC signals for simultaneously evaluating the conductivity and thickness of HMD region is proposed, and subsequently verified by finite element modeling and experiments. It has been found from the results that along with the proposed inverse method the GPEC probe is applicable to evaluation of HMD in coated conductive structures without much loss in accuracy.

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“…Visual and optical inspection are intuitive in character, but can only detect surface flaws [8,9]. Eddy current testing offers high detection efficiency, but is limited by its inapplicability to non-conductive materials [10]. Ultrasonic testing can perform deep accurate detection, but has a surface blind region and requires a coupling agent [11,12].…”

Section: Introductionmentioning

confidence: 99%

Inversion Technique for Quantitative Infrared Thermography Evaluation of Delamination Defects in Multilayered Structures

Liu

Pei

Xie

et al. 2020

IEEE Trans. Ind. Inf.

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Inverse analysis is a promising tool for quantitative evaluation offering informative model-based prediction and providing accurate reconstruction results without pre-inspections for characterization criteria. For traditional defect inverse reconstruction, a large number of parameters are required to reconstruct a complex defect, and the corresponding forward modelling simulation is very time-consuming. Such issues result in ill-posed and complex inverse reconstruction results, which further reduces its practical applicability. In this paper, we propose and experimentally validate an inversion technique for the reconstruction of complexly-shaped delamination defects in a multilayered metallic structure using signals derived from infrared thermography (IRT) testing. First, we employ a novel defect parameterization strategy based on Fourier series fitting to represent the profile of a complicated delamination defect with relatively few coefficients. Secondly, the multi-medium element modelling method is applied to enhance a FEM fast forward simulator, in order to solve the mismatching mesh issue for mesh updating during inversion. Thirdly, a deterministic inverse algorithm based on a penalty conjugate gradient algorithm is employed to realize a robust and efficient inverse analysis. By reconstructing delamination profiles with both numerically-simulated IRT signals and those obtained through laser IRT experiments, the validity, efficiency and robustness of the proposed inversion method are demonstrated for delamination defects in a double-layered plate. Based on this strategy, not only is the feasibility of the proposed method in Infrared thermography NDT validated, but the practical applicability of inversion reconstruction analysis is significantly improved.

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Pulse-modulation eddy current inspection of subsurface corrosion in conductive structures

Cited by 41 publications

References 19 publications

Pulsed Eddy Current Non-destructive Testing and Evaluation: A Review

Pulsed Eddy Current Non-destructive Testing and Evaluation: A Review

A Gradient-Field Pulsed Eddy Current Probe for Evaluation of Hidden Material Degradation in Conductive Structures Based on Lift-Off Invariance

Inversion Technique for Quantitative Infrared Thermography Evaluation of Delamination Defects in Multilayered Structures

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