Lift-off and tilt effects on eddy current sensor measurements: a 3-D finite element study

2002 ◽  
Vol 17 (1) ◽  
pp. 25-28 ◽  
Author(s):  
Y. Le Bihan
Keyword(s):  
Finite Element ◽  
Eddy Current ◽  
Current Sensor ◽  
Finite Element Study ◽  
Eddy Current Sensor ◽  
Lift Off ◽  
Element Study

Study on extraction of electrical runout in eddy current measurement using finite element method

2013 ◽  
Vol 228 (6) ◽  
pp. 1077-1086 ◽  
Author(s):  
Xiaolong Chen ◽  
Yanlong Cao ◽  
Zaiyu Lin ◽  
Jiangxin Yang ◽  
Xiaoqi Hu
Keyword(s):  
Finite Element ◽  
Relative Permeability ◽  
Imaginary Part ◽  
Eddy Current ◽  
Material Properties ◽  
Ferromagnetic Material ◽  
Current Sensor ◽  
The Real ◽  
Eddy Current Sensor ◽  
Lift Off

Electrical runout is a bottleneck problem of eddy current sensor, which is caused by the maldistribution/variation of material electromagnetic properties of measurement target. However, extraction methods of electrical runout in eddy current displacement measurement remain ambiguous. Here, a 2D finite element model for the influence analysis of conductivity and permeability of ferromagnetic material on coil impedance of eddy current sensor is reported, which will be beneficial for detecting material properties and guiding manufacturing process. The relationships between the real and imaginary part of coil impedance with the varied material conductivity, relative permeability and the lift-off, which indicates the detecting distance, are investigated. When the conductivity, relative permeability of ferromagnetic material and the lift-off vary within a certain range, the relationships between the real and imaginary part of coil impedance are all nearly linear. This paper further shows that the character of distribution of resistance and reactance in diagram under different material properties and same measuring distance is linear. Furthermore, these lines under different measuring distances are parallel. Also the character under different measuring distances and same material property is linear, but these lines under different material properties are diffuse with same intercept. Altogether, the study shows that this method based on redesign of signal processing and its circuit is feasible and instructive in separating electrical runout from the output of eddy current sensor.

Effect of Conformable Substrate Thickness on an Eddy Current Sensor Array’s Output Characteristics

2011 ◽  
Vol 335-336 ◽  
pp. 1503-1507
Author(s):  
Jin Qiang Du ◽  
Yu Ting He ◽  
Hua Ding ◽  
Hai Wei Zhang ◽  
Li Ming Wu
Keyword(s):  
Finite Element ◽  
Eddy Current ◽  
Sensor Array ◽  
Element Model ◽  
Current Sensor ◽  
Substrate Thickness ◽  
Eddy Current Sensor ◽  
Sensor Fabrication ◽  
Output Characteristics ◽  
Couple Method

A finite element model of an eddy current sensor array is built up by electromagnetic-circuit couple method, and the influences of conformable substrate thickness on sensor’s output characteristics are analyzed by the model. It is shown that the amplitude of sensing coils’ output would diminish as substrate thickness increased, besides, the discrepancies of sensing coils’ output also decrease when the substrate becoming thicker. Therefore tt is necessary to make the conformable substrate as thin as possible in sensor fabrication process to enhance the crack inspecting ability of the sensor.

Simulation Analysis of Conformable Substrate on an Eddy Current Sensor Array’s Output Characteristics Based on Finite Element Method

2011 ◽  
Vol 130-134 ◽  
pp. 2724-2728
Author(s):  
Jin Qiang Du ◽  
Yu Ting He ◽  
Hua Ding ◽  
Li Ming Wu ◽  
Qing Shao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Eddy Current ◽  
Sensor Array ◽  
Simulation Analysis ◽  
Current Sensor ◽  
Finite Element Models ◽  
Eddy Current Sensor ◽  
Output Characteristics ◽  
Couple Method

Finite element models of an eddy current sensor array are built up by electromagnetic-circuit couple method, and the influences of conformable substrate on sensor’s output characteristics are analyzed by those models. It is shown that the model contains the conformable substrate has almost the same output characteristics as the model without it, but the output amplitudes and phases of the former model are higher than the latter. Therefore we can simply the sensor as a single surface to facilitate the analysis, and then revise it to fit to the real sensor.

A finite element study of the remote field eddy current phenomenon

1988 ◽  
Vol 24 (1) ◽  
pp. 435-438 ◽  
Author(s):  
W. Lord ◽  
Y.S. Sun ◽  
S.S. Udpa ◽  
S. Nath
Keyword(s):  
Finite Element ◽  
Eddy Current ◽  
Finite Element Study ◽  
Element Study

Simulation Analysis of an Eddy Current Sensor Array Based on Finite Element Method

2011 ◽  
Vol 299-300 ◽  
pp. 1072-1077
Author(s):  
Jin Qiang Du ◽  
Yu Ting He ◽  
Hua Ding ◽  
Hai Wei Zhang ◽  
Li Ming Wu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Eddy Current ◽  
Sensor Array ◽  
Simulation Analysis ◽  
Element Model ◽  
Current Sensor ◽  
Eddy Current Sensor ◽  
Output Characteristics ◽  
Couple Method

A finite element model of an eddy current sensor array is built up by electromagnetic-circuit couple method, and the influences of crack length and frequency on sensor’s output characteristics are analyzed by this model. It is shown that the model established in this paper is reasonable. There would be a change on amplitude and phase when a crack appears below the footprint of sensing coil in metal plane, and the amplitude and phase of sensor coil are increasing gradually as crack propagation. As frequency increased, the differences between the sensing coils’ output become obvious. However, the differences begin decreasing while the frequency above 3MHz approximately. These results will provide a reference for further research and application of the sensor.

scholarly journals Lift-off tolerant pancake eddy-current sensor for the thickness and spacing measurement of non- magnetic plates

2020 ◽  
Author(s):  
Mingyang Lu ◽  
Xiaobai Meng ◽  
Ruochen Huang ◽  
Liming Chen ◽  
anthony peyton ◽  
...  
Keyword(s):  
Eddy Current ◽  
Test Piece ◽  
Triple Helix ◽  
Outer Radius ◽  
Small Error ◽  
Current Sensor ◽  
Magnetic Vector Potential ◽  
Eddy Current Sensor ◽  
Spacing Distance ◽  
Lift Off

<p>The lift-off spacing distance between the eddy current sensor and test piece will influence the detected signals and accuracy of the measurement. <a>Various techniques including novel sensor designs, features (lift-off point of intersection, lift-off invariance phenomenon), and algorithms have been proposed for the compensation of error caused by the lift-off effect using the eddy current sensor. However, few of these have directly measured the lift-off spacing distance, particularly for the distance up to 15 mm. </a>In this paper, a lift-off tolerant pancake sensor has been designed. By analysing the sensitive region of the magnetic vector potential change (due to the test piece), the receiver of the sensor is designed as a circular spiral pancake coil with a large mean radius and span length (the difference between inner and outer radius). Experiments on the inductance measurement of three different non-magnetic samples have been carried out using both the designed pancake sensor and the previous triple-helix sensor. From the experiment result, the detected signal of the designed sensor has been proved much larger than that of the triple-helix sensor. Besides, simplified algorithms have been proposed for the measurement of the lift-off spacing and thickness of non-magnetic samples when using the proposed pancake sensor. Results show that the lift-off spacing and thickness can be measured with a small error of 0.14 mm (absolute error under 209.66 kHz), and 1.35 % (relative error, under low working frequencies of 142, 238, and 338 Hz) for the lift-off spacing from 1 to 15 mm.</p>

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