scholarly journals Eddy Current Testing of the Lightning Strike Protection Layer in Aerospace Composite Structures

2020 ◽  
Author(s):  
Bo Feng ◽  
Dario J. Pasadas ◽  
Artur L. Ribeiro ◽  
Helena G. Ramos
Keyword(s):  
Eddy Current ◽  
Composite Structures ◽  
Lightning Strike ◽  
Imaging Method ◽  
Induced Voltage ◽  
Current Testing ◽  
Tuning Method ◽  
Protection Layer ◽  
Two Parameters ◽  
Eddy Current Imaging

The lightning strike protection layer, which is a mesh of metal stripes, is adhered to composite materials to dissipate the huge current induced during lightning strike. This paper presents an eddy current imaging method to inspect defects in the lightning strike protection layer. A tuning method was applied to tune the resonant frequency of excitation and sensing coils and enhance the testing results. Two parameters, namely the amplitude of induced voltage in the sensing coil and the amplitude of the voltage across a sampling resistor in the excitation circuit, were used to image the defects. The results show that the image formed by sensing coil voltage is less noisy and more accurate.

scholarly journals Methods of Controlling Lift - off in Conductivity Invariance Phenomenon for Eddy Current Testing

2020 ◽  
Author(s):  
Zhongwen Jin ◽  
Yuwei Meng ◽  
Rongdong Yu ◽  
Ruochen Huang ◽  
Mingyang Lu ◽  
...  
Keyword(s):  
Linear Relationship ◽  
Eddy Current ◽  
Coating Thickness ◽  
Test Sample ◽  
Common Point ◽  
Coil Design ◽  
Current Testing ◽  
Lift Off ◽  
Two Parameters ◽  
The Relationship

<p>Previously, a conductivity invariance phenomena (CIP) has been discovered – at a certain lift-off, the inductance change of the sensor due to a test sample is immune to conductivity variations, i.e. the inductance – lift-off curve passes through a common point at a certain lift-off, termed as conductivity invariance lift-off. However, this conductivity invariance lift-off is fixed for a particular sensor setup, which is not convenient for various sample conditions. In this paper, we propose using two parameters in the coil design – the horizontal and vertical distances between the transmitter and the receiver to control the conductivity invariance lift-off. The relationship between these two parameters and the conductivity invariance lift-off is investigated by simulation and experiments and it has been found that there is an approximate linear relationship between these two parameters and the conductivity invariance lift-off. This is useful for applications where the measurements have restrictions on lift-off, e.g. uneven coating thickness which limits the range of the lift-off of probe during the measurements. Therefore, based on this relationship, it can be easier to adjust the configuration of the probe for a better inspection of the test samples.</p>

Quantitative evaluation of surface crack in ferromagnetic materials based on Bayesian network in eddy current testing

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1073-1079
Author(s):  
Jing Song ◽  
Yanzhen Zhao
Keyword(s):  
Bayesian Network ◽  
Quantitative Evaluation ◽  
Eddy Current ◽  
Crack Size ◽  
Ferromagnetic Materials ◽  
Eddy Current Testing ◽  
Surface Cracks ◽  
Induced Voltage ◽  
Current Testing ◽  
Small Cracks

Quantitative evaluation of surface cracks using detection signal is of great significance for accurate prediction of cracks in eddy current testing. It is very difficult to evaluate both the width and depth of small cracks. A quantitative evaluation method based on Bayesian network is proposed for estimating the width and depth of surface cracks in the ferromagnetic materials. First, the simulation model of eddy current testing (ECT) is established and verified by the experimental results. Then, the variation of induced voltage with crack size is studied. Four feature points of real and imaginary part of induced voltage of the receiver coil are selected to characterize the crack size. Finally, a Bayesian network is applied to evaluate the crack size based on numerical simulation results. The evaluation results show that Bayesian network can accurately estimate the width and depth of small cracks.

scholarly journals Methods of Controlling Lift-off in Conductivity Invariance Phenomenon for Eddy Current Testing

2020 ◽  
Author(s):  
Zhongwen Jin ◽  
Yuwei Meng ◽  
Rongdong Yu ◽  
Ruochen Huang ◽  
Mingyang Lu ◽  
...  
Keyword(s):  
Linear Relationship ◽  
Eddy Current ◽  
Coating Thickness ◽  
Test Sample ◽  
Common Point ◽  
Coil Design ◽  
Current Testing ◽  
Lift Off ◽  
Two Parameters ◽  
The Relationship

Previously, a conductivity invariance phenomena (CIP) has been discovered &ndash; at a certain lift-off, the inductance change of the sensor due to a test sample is immune to conductivity variations, i.e. the inductance &ndash; lift-off curve passes through a common point at a certain lift-off, termed as conductivity invariance lift-off. However, this conductivity invariance lift-off is fixed for a particular sensor setup, which is not convenient for various sample conditions. In this paper, we propose using two parameters in the coil design &ndash; the horizontal and vertical distances between the transmitter and the receiver to control the conductivity invariance lift-off. The relationship between these two parameters and the conductivity invariance lift-off is investigated by simulation and experiments and it has been found that there is an approximate linear relationship between these two parameters and the conductivity invariance lift-off. This is useful for applications where the measurements have restrictions on lift-off, e.g. uneven coating thickness which limits the range of the lift-off of probe during the measurements. Therefore, based on this relationship, it can be easier to adjust the configuration of the probe for a better inspection of the test samples.

scholarly journals Methods of Controlling Lift - off in Conductivity Invariance Phenomenon for Eddy Current Testing

2020 ◽  
Author(s):  
Zhongwen Jin ◽  
Yuwei Meng ◽  
Rongdong Yu ◽  
Ruochen Huang ◽  
Mingyang Lu ◽  
...  
Keyword(s):  
Linear Relationship ◽  
Eddy Current ◽  
Coating Thickness ◽  
Test Sample ◽  
Common Point ◽  
Coil Design ◽  
Current Testing ◽  
Lift Off ◽  
Two Parameters ◽  
The Relationship

<p>Previously, a conductivity invariance phenomena (CIP) has been discovered – at a certain lift-off, the inductance change of the sensor due to a test sample is immune to conductivity variations, i.e. the inductance – lift-off curve passes through a common point at a certain lift-off, termed as conductivity invariance lift-off. However, this conductivity invariance lift-off is fixed for a particular sensor setup, which is not convenient for various sample conditions. In this paper, we propose using two parameters in the coil design – the horizontal and vertical distances between the transmitter and the receiver to control the conductivity invariance lift-off. The relationship between these two parameters and the conductivity invariance lift-off is investigated by simulation and experiments and it has been found that there is an approximate linear relationship between these two parameters and the conductivity invariance lift-off. This is useful for applications where the measurements have restrictions on lift-off, e.g. uneven coating thickness which limits the range of the lift-off of probe during the measurements. Therefore, based on this relationship, it can be easier to adjust the configuration of the probe for a better inspection of the test samples.</p>

Probabilistic evaluation of detection capability of eddy current testing to inspect pitting on a stainless steel clad using multiple signal features

2020 ◽  
Vol 64 (1-4) ◽  
pp. 47-55
Author(s):  
Takuma Tomizawa ◽  
Haicheng Song ◽  
Noritaka Yusa
Keyword(s):  
Stainless Steel ◽  
Eddy Current ◽  
Pressure Vessels ◽  
Eddy Current Testing ◽  
Probability Of Detection ◽  
Current Testing ◽  
Multiple Signal ◽  
Signal Features ◽  
Inner Surface ◽  
Drill Holes

This study proposes a probability of detection (POD) model to quantitatively evaluate the capability of eddy current testing to detect flaws on the inner surface of pressure vessels cladded by stainless steel and in the presence of high noise level. Welded plate samples with drill holes were prepared to simulate corrosion that typically appears on the inner surface of large-scale pressure vessels. The signals generated by the drill holes and the noise caused by the weld were examined using eddy current testing. A hit/miss-based POD model with multiple flaw parameters and multiple signal features was proposed to analyze the measured signals. It is shown that the proposed model is able to more reasonably characterize the detectability of eddy current signals compared to conventional models that consider a single signal feature.

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