Study on the Crack Detectability Based on Koch Differential Pick-up Planar Eddy Current Probe

doi:10.3901/JME.2023.10.017

Abstract

Abstract: Flexible planar eddy current probes are broadly used for the inspection of cracks which located on the surface and subsurface of components with complex shape. The flexible planar eddy current probe designed by conventional coil structure has a high rate of missed detection for short cracks in special orientations. In order to improve the detection sensitivity to cracks in different orientations and restrain the lift-off noise during the testing process, the planar Koch differential pick-up eddy current probe is proposed via combining the idea of differential pick-up with Koch fractal geometry. Through finite element analysis, the detectability performances of the probe to cracks with different orientations, lengths, widths, depths are researched. At the same time, the Koch differential pick-up probe is compared with the differential pick-up probe designed by conventional circular coil. The result of finite element analysis shows that:for the inspection of crack with 5 mm in length in 90° orientation, the peak-to-peak value (V_pp) of signal output from Koch probe is 71.8% larger than that of circular probe; the V_pp of signal output from Koch probe is 41.0% larger than that of circular probe for the inspection of crack with 3 mm in length; the V_pp of signal output from Koch probe is 142.6% larger than that of circular probe when detecting crack with 0.1 mm in width; when the crack is larger than 0.8 mm in depth, the V_pp of signal output from Koch probe is more than 1.5 times of circular probe. The results of finite element analysis and experiment show that the planar eddy current probe designed by Koch coil possesses more conspicuous edge for the inspection of short cracks compared with the circular coil.

Key words: eddy current testing, differential pick-up probe, Koch curve, fractal geometry, nondestructive testing

CLC Number:

TH878

CHEN Guolong, CAO Zheng, ZHANG Shuaishuai, JIN Wuyin. Study on the Crack Detectability Based on Koch Differential Pick-up Planar Eddy Current Probe[J]. Journal of Mechanical Engineering, 2023, 59(10): 17-29.

References

[1] 陈振茂. 电磁无损检测数值模拟方法[M]. 北京:机械工业出版社,2017. CHEN Zhenmao. Numerical simulation method for electromagnetic nondestructive testing[M]. Beijing:China Machine Press,2017.
[2] XIE Ruifang,CHEN Dixiang,PAN Mengchun,et al. Fatigue crack length sizing using a novel flexible eddy current sensor array[J]. Sensors,2015,15(12):32138-32151.
[3] ZHANG Weipeng,WANG Chenglong,XIE Fengqin,et al. Defect imaging curved surface based on flexible eddy current array sensor[J]. Measurement,2019,151(1-2):107280.
[4] CHEN Tao,HE Yuting,DU Jinqiang. A high-sensitivity flexible eddy current array sensor for crack monitoring of welded structures under varying environment[J]. Sensors,2018,18(6):1780.
[5] GOLDFINE N. Innovative sensors for measuring materials properties[J]. Materials and Processing Report,1992,7:5-7.
[6] ZILBERSTEIN V,SCHLICKER D,WALRATH K,et al. MWM eddy current sensors for monitoring of crack initiation and growth during fatigue tests and in service[J]. International Journal of Fatigue,2001,23:477-485.
[7] GOLDFINE N,SCHLICKER D,SHEIRETOV Y,et al. Conformable eddy-current sensors and arrays for fleetwide gas turbine component quality assessment[J]. Journal of Engineering for Gas Turbines & Power,2001,124(4):904-909.
[8] ZILBERSTEIN V,SHAY I,LYONS R,et al. Validation of multi-frequency eddy current MWM sensors and MWM-arrays for coating production quality and refurbishment assessment[C]//ASME Turbo Expo 2003,collocated with the 2003 International Joint Power Generation Conference,June 16-19,2003,Atlanta,Georgia,USA. 2003:1-10.
[9] SHEIRETOV Y K. Deep penetration magnetoquasistatic sensors[D]. Boston:Massachusetts Institute of Technology,2005.
[10] SUN Zhenguo,CAI Dong,ZOU Cheng,et al. A flexible arrayed eddy current sensor for inspection of hollow axle inner surfaces[J]. Sensors,2016,16(952):1-9.
[11] ZHANG Huayu,MA Longyu,XIE Fengqin. A method of steel ball surface quality inspection based on flexible arrayed eddy current sensor[J]. Measurement,2019,144:192-202.
[12] SHE Saibo,HE Yunze,CHEN Yifang,et al. Flexible floral eddy current probe for detecting flaws in metal plate[J]. IEEE Sensors Journal,2020,20(18):10521-10529.
[13] ZHANG Na,YE Chaofeng,PENG Lei,et al. Eddy current probe with three-phase excitation and integrated array TMR sensors[J]. IEEE Transactions on Industrial Electronics,2020,68(6):5325-5336.
[14] 殷晓康,李盈盈,张晓瑞,等. 基于平面线圈电容电感效应的双模式检测技术[J]. 机械工程学报,2021,57(14):168-176. YIN Xiaokang,LI Yingying,ZHANG Xiaorui,et al. Dual modality inspection technique based on capacitive-inductive effect of planar coil[J]. Journal of Mechanical Engineering,2021,57(14):168-176.
[15] RODADO L S,SANTOS T G,RAMOS P M,et al. A new dual driver planar eddy current probe with dynamically controlled induction pattern[J]. NDT & E International,2015,70:29-37.
[16] 陈国龙,张卫民,秦峰,等. 十字交叉旋转场涡流传感器的设计与实现[J]. 中国科技论文,2015,10(22):2624-2627. CHEN Guolong,ZHANG Weimin,QIN Feng,et al. The design and implementation of crisscross rotation eddy current probe[J]. China Sciencepaper,2015,10(22):2624-2627.
[17] CHEN Guolong,ZHANG Weimin,JIN Wuyin,et al. A novel rotational field eddy current planar probe with two-circular sector pickup coils[J]. Sensors,2019,19(21):4628.
[18] 陈国龙,张卫民,庞炜涵,等. 基于科赫雪花图形激励装置的涡流传感器工作原理分析[J]. 传感技术学报,2015,28(10):1454-1458. CHEN Guolong,ZHANG Weimin,PANG Weihan,et al. Analysis on the working principle of eddy current probe using the Koch curve exciting coils[J]. Chinese Journal of Sensors and Actuators,2015,28(10):1454-1458.
[19] CHEN Guolong,CAO Zheng,ZHANG Weimin. A novel planar differential Koch fractal eddy current probe with parallel wound topological structure[J]. Journal of Sensors,2021,2021:1-13.
[20] 于霞,张卫民,邱忠超,等. 飞机发动机叶片缺陷的差激励涡流传感器检测[J]. 北京航空航天大学学报,2015,41(9):1582-1588. YU Xia,ZHANG Weimin,QIU Zhongchao,et al. Differential excitation eddy current sensor testing for aircraft engine blades defect[J]. Journal of Beijing University of Aeronautics and Astronautics,2015,41(9):1582-1588.
[21] ZHANG Shurui,UCHIMOTO T,TAKAGI T,et al. Mechanism study for directivity of TR probe when applying eddy current testing to ferro-magnetic structural materials[J]. NDT & E International,2021,122:102464.