Efficient calculation of transient eddy current response from multi-layer cylindrical conductive media

The transient response from a transmitter–receiver coil system inside a multi-layer cylindrical conductive configuration is obtained. The particular set-up applies to well logging as well as to eddy current tube testing. In this work, a number of improvements are presented to existing models for an efficient calculation of the induced voltage. These include: domain truncation, novel treatment of arbitrary number of layers in order to avoid computational overflows and efficient time response calculation. The latter is based on a combination of Laplace inversion techniques for short- and long-time transient responses. This article is part of the theme issue ‘Advanced electromagnetic non-destructive evaluation and smart monitoring’.

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Pulsed Eddy Current Response to General Corrosion in Concrete Rebar

Journal of Nondestructive Evaluation Diagnostics and Prognostics of Engineering Systems ◽

10.1115/1.4047851 ◽

2020 ◽

Vol 3 (4) ◽

Author(s):

Ian Eddy ◽

P. R. Underhill ◽

J. Morelli ◽

T. W. Krause

Keyword(s):

Transient Response ◽

Exponential Decay ◽

Eddy Current ◽

Structural Integrity ◽

Concrete Structures ◽

Highway Bridges ◽

General Corrosion ◽

Current Response ◽

Pulsed Eddy Current ◽

Long Time

Abstract Corrosion of carbon steel rebar in concrete structures, such as highway bridges and buildings, has a direct impact on their structural integrity since the rebar provides the tensile strength within the structure. Rebar strength depends on the remaining effective radius of a given rod. Long-time decay up to 0.1 s, in the transient response of pulsed eddy current (PEC), was examined as a potential method to quantify general corrosion in ferromagnetic rebar. The transient response of a coaxial solenoidal drive–receive coil pair, oriented parallel to the rebar axis, was analyzed over a range of distances into the concrete (liftoff) and rebar radii. At long times, the single exponential decay constant was largely independent of liftoff. A power law relationship for the characteristic decay time, consistent with long-time diffusion of electromagnetic fields into a rod, was observed. The intercept of a best-fit line to measured voltage decay decreased exponentially with liftoff and maintained a measurable response up to 110 mm distance for a 25 mm (1 in.) diameter rebar. This exponential decay was present in 22 mm (7/8 in.), 19 mm (3/4 in.), and 15 mm (5/8 in.) samples as well. Reported results demonstrate the potential for PEC to quantify remaining cross-sectional area of rebar in concrete structures.

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New Proposal for Inverse Algorithm Enhancing Noise Robust Eddy-Current Non-Destructive Evaluation

Sensors ◽

10.3390/s20195548 ◽

2020 ◽

Vol 20 (19) ◽

pp. 5548

Author(s):

Milan Smetana ◽

Lukas Behun ◽

Daniela Gombarska ◽

Ladislav Janousek

Keyword(s):

Eddy Current ◽

Signal To Noise Ratio ◽

Principal Component ◽

Noise Robustness ◽

Current Response ◽

Inverse Algorithm ◽

Material Defects ◽

Non Destructive Evaluation ◽

Noise Robust ◽

Non Destructive

Solution of inverse problem in eddy-current non-destructive evaluation of material defects is concerned in this study. A new inverse algorithm incorporating three methods is proposed. The wavelet transform of sensed eddy-current responses complemented by the principal component analysis and followed by the neural network classification are employed for this purpose. The goal is to increase the noise robustness of the evaluation. The proposed inverse algorithm is tested using real eddy-current response data gained from artificial electro-discharge machined notches made in austenitic stainless-steel biomaterial. Eddy-current responses due to the material defects are acquired using a newly developed eddy-current probe that senses separately three spatial components of the perturbed electromagnetic field. The presented results clearly show that the error in evaluation of material defect depth using the proposed algorithm is less than 10% even when the signal-to-noise ratio is as high as 10 dB.

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Fault Localization of Power-Ground Short via Signal Injection and Oscilloscope Technique

ISTFA 2010: Conference Proceedings from the 36th International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2010p0202 ◽

2010 ◽

Author(s):

Binh Nguyen

Keyword(s):

Low Cost ◽

Short Circuit ◽

Fault Localization ◽

Fault Isolation ◽

Test Apparatus ◽

Good Working ◽

Signal Injection ◽

Set Up ◽

Non Destructive ◽

Short Circuit Condition

Abstract For those attempting fault isolation on computer motherboard power-ground short issues, the optimal technique should utilize existing test equipment available in the debug facility, requiring no specialty equipment as well as needing a minimum of training to use effectively. The test apparatus should be both easy to set up and easy to use. This article describes the signal injection and oscilloscope technique which meets the above requirements. The signal injection and oscilloscope technique is based on the application of Ohm's law in a short-circuit condition. Two experiments were conducted to prove the effectiveness of these techniques. Both experiments simulate a short-circuit condition on the VCC3 power rail of a good working PC motherboard and then apply the signal injection and oscilloscope technique to localize the short. The technique described is a simple, low cost and non-destructive method that helps to find the location of the power-ground short quickly and effectively.

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