Design of orthogonal eddy-current probe for weld crack detection of carbon-steel plate

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1347-1355
Author(s):  
Tao Chen ◽  
Xiaoqi Xiao ◽  
Lihong Zhang ◽  
Cheng Lv ◽  
Zhiyang Deng ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Eddy Current ◽  
Crack Detection ◽  
Steel Plate ◽  
Signal To Noise Ratio ◽  
Detection Sensitivity ◽  
Scanning Angle ◽  
Length Width ◽  
Lift Off ◽  
Detection Effect

Due to uneven surface and lift-off effect, it is difficult to detect weld crack by eddy-current testing. A new orthogonal eddy-current probe for weld crack detection of carbon-steel plate was designed in this paper. Based on COMSOL Multiphysics, the influence of scanning angle on detection sensitivity of the probe was compared firstly. Then, the effects of coil width, coil side length, detection coil height, and lift-off distance on detection sensitivity of the probe were studied, respectively. Finally, the test piece of carbon-steel plate weld with crack, and the physical probe used to verify the crack detection effect were made. The experimental results show that the weld crack of carbon-steel plate with length × width × depth of 20.0 mm × 0.3 mm × 1 mm can be effectively identified, and the lift-off noise can be effectively suppressed by the method presented in this paper. At the same time, the signal-to-noise ratio of the probe keeps constant in the lift-off distance range of 0.3 mm–3.0 mm.

scholarly journals Research on Detection Mechanism of Weld Defects of Carbon Steel Plate Based on Orthogonal Axial Eddy Current Probe

Sensors ◽  
2020 ◽  
Vol 20 (19) ◽  
pp. 5515
Author(s):  
Linnan Huang ◽  
Chunhui Liao ◽  
Xiaochun Song ◽  
Tao Chen ◽  
Xu Zhang ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Eddy Current ◽  
Steel Plate ◽  
Difficult Problem ◽  
Eddy Current Testing ◽  
Detection Sensitivity ◽  
Detection Mechanism ◽  
Current Testing ◽  
Weld Defects ◽  
Lift Off

The uneven surface of the weld seam makes eddy current testing more susceptible to the lift-off effect of the probe. Therefore, the defect of carbon steel plate welds has always been a difficult problem in eddy current testing. This study aimed to design a new type of eddy current orthogonal axial probe and establish the finite element simulation model of the probe. The effect of the probe structure, coil turns, and coil size on the detection sensitivity was simulated. Further, a designed orthogonal axial probe was used to conduct a systematic experiment on the weld of carbon steel specimens, and the 0.2 mm width and 1 mm depth of weld defects of carbon steel plates were effectively detected. The experimental results showed that the new orthogonal axial eddy current probe effectively suppressed the unevenness effect of the weld surface on the lift-off effect during the detection process.

scholarly journals Investigate the effect of lift-off on eddy current signal for carbon steel plate

2018 ◽  
Vol 225 ◽  
pp. 06005
Author(s):  
Moneer A Faraj ◽  
Fahmi Samsuri ◽  
Ahmed N AbdAlla ◽  
Damhuji Rifai ◽  
Kharudin Ali ◽  
...  
Keyword(s):  
Eddy Current ◽  
Steel Plate ◽  
Current Signal ◽  
Independent Variables ◽  
Investigation Methods ◽  
Interaction Equation ◽  
Lift Off ◽  
The Relationship ◽  
Factor Interaction ◽  
Two Independent Variables

In this study, the effect of various factors like lift-off and depth defect on the eddy current signal was investigated. Investigation methods like response surface methodology (RSM) and composed central design (CCD) were employed to establish the relationship between lift-off distance, depth of a defect and the eddy current signal by the two-factor interaction equation, and would provide a reference in further to accurate the depth defect. The regression analysis suggested that eddy current signal was well fitted by the two-factor interaction equation (R2 = 0.9656). The eddy current signal was investigated by varying the levels of these two independent variables, in which all have significant influences on eddy current signal. There would be a change in the amplitude and when lift-off distance is altered, and lift off distance increased, the increase of the amplitude of output signal decrease gradually.

Measurement of Wall Thinning through Insulation with Ferromagnetic Cladding Using Pulsed Eddy Current Testing

2011 ◽  
Vol 301-303 ◽  
pp. 426-429
Author(s):  
Zhi Yuan Xu ◽  
Xin Jun Wu ◽  
Chen Huang ◽  
Yi Hua Kang
Keyword(s):  
Eddy Current ◽  
Steel Plate ◽  
Thickness Measurement ◽  
Measurement Range ◽  
Galvanized Steel ◽  
Shielding Effect ◽  
Pulsed Eddy Current ◽  
Wall Thinning ◽  
The Common ◽  
Lift Off

Pulsed eddy current (PEC) technique has been successfully used for measuring wall thinning of carbon steel equipments without removal of the insulation. In field applications, the probe performance decreases in presence of ferromagnetic claddings. This paper presents a method based on saturation magnetization to solve this problem. The main principle of this method is to weaken the magnetic shielding effect of the cladding by magnetizing it to saturation. A U-shaped magnetizer is designed to realize this method. Contrast experiments are performed on a Q235 steel plate covered by a galvanized steel cladding. The experiment results show that the thickness measurement range and lift-off range are increased by applying this method to the common PEC probe.

Eddy Current Detecting of Leak Hole in Pipeline by Wavelet Packet Signal Analysis Method

2013 ◽  
Vol 291-294 ◽  
pp. 2486-2491
Author(s):  
Yue Shen ◽  
Ling Tan Zhang
Keyword(s):  
Eddy Current ◽  
Steel Plate ◽  
Multiple Scales ◽  
Signal To Noise Ratio ◽  
Wavelet Packet ◽  
Measuring Method ◽  
Transient Signal ◽  
Measured Signal ◽  
Accurate Identification ◽  
Time Frequency

In the process of detecting leak hole in pipeline by intelligent pig with eddy current measuring method, the cut off effect of eddy current field in the closed cross section of leak hole in steel plate is weak due to geometric deformation of eddy current on the edge of the hole produced by destroyed drilling. As a result, the measured signal is very unobvious. Meanwhile, owing to the rough surface of steel plate, the periodic interference generated by movement of the detecting probe cannot be eliminated or be inhibited easily by conventional signal processing methods for its large amplitude and approximate frequency band with the leak hole signals, the signal to noise ratio (SNR) of measured signal is very low and the accurate identification of leak hole cannot be guaranteed. The wavelet transform, with characteristics of time-frequency localization and multiple scales, is a useful and effective method for identifying singularity of the signals and adapts to detect the transient signal or extract non-stationary information in the signals with strong periodic interference and noise. The reconstructing signal SNR will be increased greatly in eddy current detecting of leak hole in the pipeline with wavelet packet analysis of the signal by constructing the self-defined cost function based on maximum SNR to obtain optimal wavelet packet basis function. This ensures good detection and location of leak hole in the pipeline.

Evaluating the III-Posedness of Inverse Problem to Size Flaws from Eddy Current NDT Signals Obtained with an Absolute Type Probe

2014 ◽  
Vol 619 ◽  
pp. 337-341
Author(s):  
Noritaka Yusa ◽  
Hiroki Shishido ◽  
Hidetoshi Hashizume
Keyword(s):  
Eddy Current ◽  
Signal To Noise Ratio ◽  
Constant Width ◽  
Three Dimensional ◽  
Coil Diameter ◽  
Dimensional Finite Element ◽  
The Difference ◽  
Lift Off ◽  
Three Dimensional Finite Element ◽  
Non Destructive

This study discusses the applicability of eddy current testing to the non-destructive evaluation of the depth of a flaw. Three-dimensional finite element simulations are carried out to calculate eddy current signals due to a flaw, and subsequent calculations correlate the difference between signals due to two flaws with the difference between the depths of the flaws. Standard deviation of the difference between the depths of the flaws is used to discuss the ill-posedness of the problem. A flaw is modeled as a sufficiently long rectangular region with a constant width and uniform electrical conductivity; an absolute pancake probe is considered. This study reveals that lift-off and coil diameter do not have a large effect on the ill-posedness, which supports that it is reasonable to decide parameters in actual inspections so that signal-to-noise ratio is maximized. The results obtained also indicate the difficulty in evaluating the depth of a flaw deeper than 1 mm using the signals obtained using an absolute pancake probe.

scholarly journals Analysis of Lift-Off Effect on Transmitter-Receiver Probe in Eddy Current Testing

2020 ◽  
Author(s):  
Qing Zhang ◽  
Xin Li ◽  
Guiyun Tian
Keyword(s):  
Analytical Model ◽  
Eddy Current ◽  
Signal To Noise Ratio ◽  
Ferromagnetic Materials ◽  
Eddy Current Testing ◽  
Probe Design ◽  
Deep Penetration ◽  
Current Testing ◽  
Straight Line ◽  
Lift Off

The Transmitter-Receiver Probe (TR probe), which has improved signal-to-noise ratio, deep penetration depth, and directional measurement is used in pulsed eddy current testing (PECT). Whereas, the lift-off effect on the TR probe is one of the main obstacles. The purpose of this paper is to analyze the lift-off effects on the TR probe and presents a feature for lift-off estimation. Firstly, an analytical model of a TR probe is given based on previous studies. Secondly, on the basics of the analytical model, the spectrum of the PECT signal is studied, and the lift-off effects on the TR probe are analyzed. Then, the lift-off effects under different coil distances are studied and a D Intersect Point (DIP) is proposed for the lift-off estimation. Results show that the TR probe can be used to reduce the lift-off effect for the non-ferromagnetic materials and the ferromagnetic materials. And both the DIP time and amplitude can be used for lift-off estimation. However, the DIP time is better, as its evolution curve with lift-off is a straight line with the same slope. The study is believed to be helpful for the TR probe design, the lift-off measurement, and the thickness assessment and defect quantification.

scholarly journals Rotating Focused Field Eddy-Current Sensing for Arbitrary Orientation Defects Detection in Carbon Steel

Sensors ◽  
2020 ◽  
Vol 20 (8) ◽  
pp. 2345 ◽  
Author(s):  
Zhiyuan Xu ◽  
Xiang Wang ◽  
Yiming Deng
Keyword(s):  
Magnetic Field ◽  
Carbon Steel ◽  
Eddy Current ◽  
Signal To Noise Ratio ◽  
Signal Amplitude ◽  
Element Model ◽  
Rotating Magnetic Field ◽  
Design Parameters ◽  
Arbitrary Orientation ◽  
Focusing Effect

This paper presents a rotating focused field eddy-current (EC) sensing technique, which leverages the advantages of magnetic field focusing and rotating magnetic field, for arbitrary orientation defects detection. The sensor consists of four identical excitation coils orthogonally arranged in an upside-down pyramid configuration and a giant magneto-resistive (GMR) detection element. The four coils are connected to form two figure-8-shaped focusing sub-probes, which are fed by two identical harmonic currents with 90 degrees phase difference. A finite element model-based study of arbitrary orientation defects detection was performed to understand the probe operational characteristics and optimize its design parameters. Probe prototyping and experimental validation were also carried out on a carbon steel plate specimen with four prefabricated surface-breaking defects. In-situ spot inspection with the probe rotating above the defect and a manual line-scan inspection were both conducted. Results showed that the probe has the capability of detecting defects with any orientations while maintaining the same sensitivity and the defect depth can be quantitatively evaluated by using the signal amplitude. Compared with the existing rotating field probes, the presented probe does not require additional excitation adjustment or data fusion. Meanwhile, due to its focusing effect, it can generate a strong rotating magnetic field at the defect location with a weak background noise, thus yielding superior signal-to-noise ratio.

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