An approach to reduce lift-off noise in pulsed eddy current nondestructive technology

Yu, Yating; Yan, Yue; Wang, Fei; Tian, Guohui; Zhang, Dejun

doi:10.1016/j.ndteint.2013.12.012

Cited by 78 publications

(30 citation statements)

References 17 publications

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“…Therefore, lift-off effect is the main obstacle for thickness measurement using ECS. Different approaches used signal processing, sensor structure, and detection principle to identify lift-off for compensation or find invariant features for the reduction of lift-off effects for SEC and PEC sensors [9], [10]. As a frequency-domain method that can provide information at different depths, MEC sensors were also developed to measure metal thickness or conductivity [11], [12].…”

mentioning

confidence: 99%

Noncontact Thickness Measurement of Metal Films Using Eddy-Current Sensors Immune to Distance Variation

Wang

Feng

2015

IEEE Trans. Instrum. Meas.

115

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A simple method for measuring the thickness of metal films based on eddy-current sensors (ECSs) immune to distance variation is proposed. The slope of the lift-off curve (LOC) in the RL impedance plane is a good feature for characterizing target thickness independent of lift-off distance variation. A simple equivalent model was built to deal with the ECS problem, and the essential relationship between the slope of LOC (SLOC) and target properties was obtained. Full finite element analysis was conducted to analyze the relationship between SLOC feature and target thickness, and the results matched the modeling results very well. A sensor coil probe was then manufactured and used to measure the thickness of copper films with high performance, and the capability of this technique for online noncontact thickness measurement was verified. The basic characteristics and performances of this thickness measurement technique were tested and discussed. The SLOC feature for thickness measurement had significant advantages, such as simplicity, reliability, immunity to the lift-off effect (most important), high speed, simple signal processing, and negligible design limitation of the sensor probe. The results of this paper revealed that online thickness measurement systems could be developed for various advanced industrial applications.Index Terms-Eddy-current sensor (ECS), electromagnetic measurement, impedance measurement, industrial applications, lift-off curve (LOC), metal films, sensor system, slope of LOC (SLOC), thickness measurement.

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mentioning

confidence: 99%

Noncontact Thickness Measurement of Metal Films Using Eddy-Current Sensors Immune to Distance Variation

Wang

Feng

2015

IEEE Trans. Instrum. Meas.

115

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“…A technique to indirectly reduce the effects of lift-off by using the slope of the difference signal has been proposed [76]. The technique is potentially useful in the measurement of depth of surface defect.…”

Section: Lift-off Problemmentioning

confidence: 99%

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

Sophian

Tian

Fan

2017

Chin. J. Mech. Eng.

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215

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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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“…In a different study, Yu et al [74] modeled the lift-off effect introduced by various coating thicknesses from irregular sample surface or movement of transducers. However, simplification of the measurement should be further improved and widen the proposed application on the sample with the ferrous material and on the subsurface defect.…”

Section: Pulsed Eddy Current (Pec)mentioning

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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An approach to reduce lift-off noise in pulsed eddy current nondestructive technology

Cited by 78 publications

References 17 publications

Noncontact Thickness Measurement of Metal Films Using Eddy-Current Sensors Immune to Distance Variation

Noncontact Thickness Measurement of Metal Films Using Eddy-Current Sensors Immune to Distance Variation

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

Defect Characterization Based on Eddy Current Technique: Technical Review

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