Lift-Off Point of Intercept (LOI) Behavior

Lefebvre, J. H. V.; Dubois, J. M. S.

doi:10.1063/1.1916720

Cited by 10 publications

(4 citation statements)

References 4 publications

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“…To enable the interpretation of LOI signals, the characteristics of LOI signals in terms of time and amplitude were revealed under a wide variety of conditions. The results demonstrate that LOI signals including both the time and amplitude follow a unique curve against thickness and conductivity [69]. At the early stage, LOI phenomenon could only exist when a PEC probe using a coil as the receiver is placed above a nonferrous sample.…”

Section: Lift-off Problemmentioning

confidence: 84%

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

Sophian

Tian

Fan

2017

Chin. J. Mech. Eng.

198

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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: Lift-off Problemmentioning

confidence: 84%

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

Sophian

Tian

Fan

2017

Chin. J. Mech. Eng.

198

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“…LOI, was employed to characterize the hidden corrosion. Other features, such as peak value, zero-crossing time [1], or the features from the transform domain [19] may be considered It is observed that such a slice is not fixed with the presence of corrosion [12]. Therefore, the preselected LOI slice may not be the optimal one for the quantification process.…”

Section: Discussionmentioning

confidence: 99%

Combining multiple nondestructive inspection images with a generalized additive model

Liu

Ramuhalli

Safizadeh

et al. 2008

Meas. Sci. Technol.

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In this paper, multiple nondestructive inspection (NDI) images are combined with a generalized additive model to achieve a more precise and reliable assessment of hidden corrosion in aircraft lap joints. Two inspection techniques are considered in this study. One is the conventional multi-frequency eddy current testing technique and the other is the pulsed eddy current technique. To characterize the thickness loss or equivalently to achieve a quantitative measure of corrosion, multiple NDI images are fused to produce a thickness map that reflected the amount of corrosion damage. These results are further compared with corresponding digital x-ray thickness maps, which are obtained by mapping the remaining thickness after the specimen is dissembled and all the corrosion products are cleaned. Experimental results demonstrate that the proposed algorithms outperform the traditional calibration method aligned with a single testing approach.

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“…Generally, pulsed eddy current signals are analysed for many signal features like peak amplitude, peak arrival time, zero crossing time etc. The LOI-based methodology [8,[14][15][16][17] estimates the signal slopes near the Lift-off point of Intersection (LOI) and correlates them to the gap between the sensor face and the test specimen. The LOI-based methodology is preferred over other signal features such as peak amplitude, peak arrival time, and zero crossing time because it is largely immune to changes in electrical conductivity [14].…”

Section: Philosophy Of Measurementmentioning

confidence: 99%

High-Temperature Creep Measurement in Metallic Alloys Using Pulsed Eddy Current Sensors: Influence of Geometry and Magnetic Properties

Venkatesulu,

Sharma,

Patankar

et al. 2024

I2M

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Due to limited space constraints, the creep measurement of test specimens in material testing reactors is done mostly by time consuming offline techniques viz.: air gauges, diameter gauges, etc. A new compact sensor based on pulsed eddy current testing technique is designed for online creep measurement during mechanical properties testing of metallic alloy specimens for future nuclear reactors. The pulsed eddy current sensors that are positioned opposite to the test specimen measure gaps to estimate creep, by analyzing the slopes of the signals near the Lift-off point of Intersection (LOI) region. The paper discusses the temporal shifts in pulsed eddy current signals when operated at room and high temperatures. Experiments were carried out at room temperature to study the effect of geometry change on test specimens on the linearity and sensitivity of the signals.Similarly, the effect of magnetic test specimens on measurement methodology and sensitivity is also briefed. The results of the study have provided us with confidence in using the online creep measurement sensor technology in material testing reactors with a molten metal coolant medium environment. This technology will help us evaluate the mechanical properties of metallic alloy test specimens, which are intended for use in future generation nuclear reactors.

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Lift-Off Point of Intercept (LOI) Behavior

Cited by 10 publications

References 4 publications

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

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

Combining multiple nondestructive inspection images with a generalized additive model

High-Temperature Creep Measurement in Metallic Alloys Using Pulsed Eddy Current Sensors: Influence of Geometry and Magnetic Properties

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