首页|Lift-Off Effect of Koch and Circular Differential Pickup Eddy Current Probes

Lift-Off Effect of Koch and Circular Differential Pickup Eddy Current Probes

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A flexible or planar eddy current probe with a differential structure can suppress the lift-off noise during the inspec-tion of defects.However,the extent of the lift-off effect on differential probes,including different coil structures,varies.In this study,two planar eddy current probes with differential pickup structures and the same size,Koch and circular probes,were used to compare lift-off effects.The eddy current distributions of the probes perturbed by 0° and 90° cracks were obtained by finite element analysis.The analysis results show that the 90° crack can impede the eddy current induced by the Koch probe even further at relatively low lift-off distance.The peak-to-peak values of the signal output from the two probes were compared at different lift-off distances using finite element analysis and experimental methods.In addition,the effects of different frequencies on the lift-off were studied experimentally.The results show that the signal peak-to-peak value of the Koch probe for the inspection of cracks in 90° orientation is larger than that of the circular probe when the lift-off distance is smaller than 1.2 mm.In addition,the influence of the lift-off distance on the peak-to-peak signal value of the two probes was studied via normalization.This indicates that the influence becomes more evident with an increase in excitation frequency.This research discloses the lift-off effect of differential planar eddy current probes with different coil shapes and proves the detection merit of the Koch probe for 90° cracks at low lift-off distances.

Eddy current testingDifferential pickup probeFractal Koch curveFlexible eddy current probe

Guolong Chen、Zheng Cao、Shuaishuai Zhang、Ji Wei、Wei Gao、Wuyin Jin

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School of Mechanical and Electrical Engineering,Lanzhou University of Technology,Lanzhou 730050,China

Gansu Provincial Natural Science Foundation of China国家自然科学基金国家自然科学基金Hongliu Youth Found of Lanzhou University of TechnologyGansu Provincial Outstanding Graduate Student Innovation Star of China

22JR5RA22951807086121620212021CXZX-453

2024

10.1186/s10033-024-01027-3

中国机械工程学报
中国机械工程学会

中国机械工程学报

CSTPCD
影响因子：0.765
ISSN：1000-9345
年,卷(期)：2024.37(2)