Elimination of liftoff effect using a model-based method for eddy current characterization of a plate

Fan, Mengbao; Cao, Binghua; Yang, Panpan; Li, Wei; Tian, Guohui

doi:10.1016/j.ndteint.2015.05.007

Cited by 48 publications

(20 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The efforts to reduce the discrepancy should be made for accuracy improvement. In addition, uncertainty analysis should also be performed to evaluate the proposed methods [97].…”

Section: Challenges and Opportunitiesmentioning

confidence: 99%

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

Sophian

Tian

Fan

2017

Chin. J. Mech. Eng.

Self Cite

198

View full text Add to dashboard Cite

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.

show abstract

“…The efforts to reduce the discrepancy should be made for accuracy improvement. In addition, uncertainty analysis should also be performed to evaluate the proposed methods [97].…”

Section: Challenges and Opportunitiesmentioning

confidence: 99%

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

Sophian

Tian

Fan

2017

Chin. J. Mech. Eng.

Self Cite

198

View full text Add to dashboard Cite

show abstract

“…Basically, determination of sample parameters can be regarded as an inverse electromagnetic problem and most inversion methods are classified as either iterative or noniterative [15][16][17][18][19]. Iterative approaches take parameter characterization as an optimization problem.…”

Section: Introductionmentioning

confidence: 99%

“…An advantage of iterative approaches lies in simultaneous measurement of multiple parameters when the resultant changes of THz pulses are difficult to decouple. However, iterative approaches are subject to heavy computational burdens as they keep iteratively implementing forward models till they meet predefined convergence criteria [15]. In contrast, noniterative approaches, which need to seek for one or more appropriate features, are efficient and fairly popular.…”

Section: Introductionmentioning

confidence: 99%

“…In contrast, noniterative approaches, which need to seek for one or more appropriate features, are efficient and fairly popular. Noniterative approaches typically rely on the established relationship between the extracted signal features and the parameters of a sample, ignoring the underlying physical process [15]. Noniterative approaches are much more efficient than iterative approaches.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Enhanced Measurement of Paper Basis Weight Using Phase Shift in Terahertz Time-Domain Spectroscopy

2017

Self Cite

View full text Add to dashboard Cite

THz time-domain spectroscopy has evolved as a noncontact, safe, and efficient technique for paper characterization. Our previous work adopted peak amplitude and delay time as features to determine paper basis weight using terahertz time-domain spectroscopy. However, peak amplitude and delay time tend to suffer from noises, resulting in degradation of accuracy and robustness. This paper proposes a noise-robust phase-shift based method to enhance measurements of paper basis weight. Based on Fresnel Formulae, the physical relationship between phase shift and paper basis weight is formulated theoretically neglecting multiple reflections in the case of normal incidence. The established formulation indicates that phase shift correlates linearly with paper basis weight intrinsically. Subsequently, paper sheets were stacked to fabricate the samples with different basis weights, and experimental results verified the developed mathematical formulation. Moreover, a comparison was made between phase shift, peak amplitude, and delay time with respect to linearity, accuracy, and noise robustness. The results show that phase shift is superior to the others.

show abstract

“…There are many factors that affect the performance of model-free based characterization of defects. Extensive investigations have been conducted to improve defect characterization with regard to reduction of liftoff effect, new design and optimization of probes, and feature extraction [ 11 , 15 ]. The liftoff effect, which is the variation of the distance between the probe and the specimen, produces unwanted noise and degrades probe signals significantly.…”

Section: Introductionmentioning

confidence: 99%

Frequency Optimization for Enhancement of Surface Defect Classification Using the Eddy Current Technique

Fan

Wang

Cao

et al. 2016

Sensors

Self Cite

View full text Add to dashboard Cite

Eddy current testing is quite a popular non-contact and cost-effective method for nondestructive evaluation of product quality and structural integrity. Excitation frequency is one of the key performance factors for defect characterization. In the literature, there are many interesting papers dealing with wide spectral content and optimal frequency in terms of detection sensitivity. However, research activity on frequency optimization with respect to characterization performances is lacking. In this paper, an investigation into optimum excitation frequency has been conducted to enhance surface defect classification performance. The influences of excitation frequency for a group of defects were revealed in terms of detection sensitivity, contrast between defect features, and classification accuracy using kernel principal component analysis (KPCA) and a support vector machine (SVM). It is observed that probe signals are the most sensitive on the whole for a group of defects when excitation frequency is set near the frequency at which maximum probe signals are retrieved for the largest defect. After the use of KPCA, the margins between the defect features are optimum from the perspective of the SVM, which adopts optimal hyperplanes for structure risk minimization. As a result, the best classification accuracy is obtained. The main contribution is that the influences of excitation frequency on defect characterization are interpreted, and experiment-based procedures are proposed to determine the optimal excitation frequency for a group of defects rather than a single defect with respect to optimal characterization performances.

show abstract

Elimination of liftoff effect using a model-based method for eddy current characterization of a plate

Cited by 48 publications

References 22 publications

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

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

Enhanced Measurement of Paper Basis Weight Using Phase Shift in Terahertz Time-Domain Spectroscopy

Frequency Optimization for Enhancement of Surface Defect Classification Using the Eddy Current Technique

Contact Info

Product

Resources

About