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331 results on '"Kang, Yihua"'

19. Bottom Crack Detection with Real-Time Signal Amplitude Correction Using EMAT-PEC Composite Sensor.

Author

Guo, Yizhou, Hu, Yu, Wang, Kai, Song, Yini, Feng, Bo, Kang, Yihua, and Duan, Zhaoqi

Subjects
ELECTROMAGNETIC testing, ACOUSTIC transducers, FINITE element method, SIGNAL detection, SIGNALS & signaling, ULTRASONIC testing
Abstract

During electromagnetic ultrasonic testing, it is difficult to recognize small-size bottom cracks by time of flight (ToF), and the lift-off fluctuation of the probe affects the accuracy and consistency of the inspection results. In order to overcome the difficulty, a novel composite sensor of an electromagnetic acoustic transducer (EMAT) and pulse eddy current (PEC) is designed. We use the amplitude of a bottom echo recorded by EMAT to identify the tiny bottom crack as well as the amplitude of PEC signals picked up by the integrated symmetric coils to measure the average lift-off of the probe in real time. Firstly, the effects of lift-off and bottom cracks on the amplitude of bottom echo are distinguished by combining the theoretical analysis and finite element method (FEM). And then an amplitude correction method based on the fusion of EMAT and PEC signals is proposed to reduce the impact of lift-off on the defect signal. The experimental results demonstrate that the designed composite sensor can effectively detect a bottom crack as small as 0.1 mm × 0.3 mm. The signal fusion method can accurately correct the amplitude of defect signals and the relative error is less than ±8%. [ABSTRACT FROM AUTHOR]

Published
2024
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37. A Novel Leakage Magnetic Field Enhancement Method Based on Permeability Perturbation

Author

Wang, Rongbiao, Tang, Jian, Yu, Haozhi, Feng, Bo, Kang, Yihua, and Song, Kai

Abstract

The magnetic flux leakage (MFL) testing method is widely applied in detecting ferromagnetic materials, such as steel pipes. In order to protect the magnetic sensor, nonferromagnetic wear-resistant materials are placed between the sensor and the tested workpiece by conventional MFL. However, the leakage magnetic field (LMF) decays exponentially in the air, reducing the sensitivity. To improve the sensitivity of MFL, a novel approach for enhancing the LMF based on permeability perturbation is proposed in this article. The ferromagnetic materials are used as the medium between the sensor and the workpiece. The ferromagnetic medium generates a magnetic permeability perturbation area under the effect of the LMF, changing the magnetic reluctance in this local area. The difference in the magnetic reluctance in the medium influences the magnetizing field, and an additional LMF is formed, which enhances the LMF. Experiments found that the enhancement effects of different magnetic mediums with different magnetic characteristics were different. Different materials’ enhancement mechanism was analyzed by considering the saturated magnetization. Compared with conventional MFL, the method proposed in this article can increase the LMF and improve the sensitivity of MFL.

Published
2024
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