{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,25]],"date-time":"2026-03-25T21:48:26Z","timestamp":1774475306053,"version":"3.50.1"},"reference-count":28,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2022,5,9]],"date-time":"2022-05-09T00:00:00Z","timestamp":1652054400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China (NSFC)","doi-asserted-by":"publisher","award":["51875226"],"award-info":[{"award-number":["51875226"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Magnetic flux leakage (MFL) testing is widely used in non-destructive testing of ferromagnetic components. In view of the serious attenuation of the leakage magnetic field (LMF) caused by the transmission of LMF in the lift-off layer between the measuring point and the workpiece, this paper introduces an MFL detection method based on the slotted ferromagnetic lift-off layer (SFLL). The conventional non-ferromagnetic lift-off layer is changed to a ferromagnetic lift-off layer with a rectangular slot. The magnetic sensor is fixed above the slot and scans the workpiece together with the lift-off layer. First, the detection mechanism of the new method was studied by an equivalent LMF coil model. The permeability perturbation effect and the magnetization enhancement effect were analyzed in the new method. Based on the detection mechanism, the lift-off tolerance of the new method was investigated. Then, the LMF enhancement and lift-off tolerance of the new method in the steel plate detection model were studied. Finally, experiments were conducted to compare the new method with the conventional method. The simulation and experimental results show that the slotted ferromagnetic lift-off layer enhances the amplitude of the MFL signal and is tolerant to the lift-off value. This method provides a new idea for optimizing the design of the MFL sensor and improving the sensitivity of MFL detection at a large lift-off value.<\/jats:p>","DOI":"10.3390\/s22093587","type":"journal-article","created":{"date-parts":[[2022,5,10]],"date-time":"2022-05-10T00:30:28Z","timestamp":1652142628000},"page":"3587","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":17,"title":["Mechanism of Magnetic Flux Leakage Detection Method Based on the Slotted Ferromagnetic Lift-Off Layer"],"prefix":"10.3390","volume":"22","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9658-209X","authenticated-orcid":false,"given":"Jian","family":"Tang","sequence":"first","affiliation":[{"name":"School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5339-1522","authenticated-orcid":false,"given":"Rongbiao","family":"Wang","sequence":"additional","affiliation":[{"name":"Key Laboratory of Nondestructive Testing, Ministry of Education, Nanchang Hangkong University, Nanchang 330063, China"}]},{"given":"Gongzhe","family":"Qiu","sequence":"additional","affiliation":[{"name":"School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China"}]},{"given":"Yu","family":"Hu","sequence":"additional","affiliation":[{"name":"School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2622-4769","authenticated-orcid":false,"given":"Yihua","family":"Kang","sequence":"additional","affiliation":[{"name":"School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China"}]}],"member":"1968","published-online":{"date-parts":[[2022,5,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"46","DOI":"10.1016\/j.ndteint.2016.03.006","article-title":"Current Deflection NDE for the Inspection and Monitoring of Pipes","volume":"81","author":"Jarvis","year":"2016","journal-title":"NDT E Int."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"77","DOI":"10.1016\/j.ndteint.2006.07.002","article-title":"Application of Eddy Currents Induced by Permanent Magnets for Pipeline Inspection","volume":"40","author":"Nestleroth","year":"2007","journal-title":"NDT E Int."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"66","DOI":"10.1016\/j.ijpvp.2018.09.006","article-title":"A Reference Free Ultrasonic Phased Array to Identify Surface Cracks in Welded Steel Pipes Based on Transmissibility","volume":"168","author":"Zhou","year":"2018","journal-title":"Int. J. Press. Vessel. Pip."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"164650","DOI":"10.1016\/j.ijleo.2020.164650","article-title":"Numerical Simulation of Laser-Generated Ultrasonic Waves for Detection Surface Defect on a Cylinder Pipe","volume":"212","author":"Zeng","year":"2020","journal-title":"Optik"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"3307","DOI":"10.1007\/s00170-020-06467-4","article-title":"Automated Vision System for Magnetic Particle Inspection of Crankshafts Using Convolutional Neural Networks","volume":"112","author":"Tout","year":"2021","journal-title":"Int. J. Adv. Manuf. Technol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1784\/insi.2012.55.1.29","article-title":"An Automatic Magnetic Particle Inspection System for Detecting Defects in Mooring Chains","volume":"55","author":"Xin","year":"2013","journal-title":"Insight"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"84","DOI":"10.1007\/s10921-020-00730-0","article-title":"A Novel Magnetic Flux Leakage Testing Method Based on AC and DC Composite Magnetization","volume":"39","author":"Wang","year":"2020","journal-title":"J. Nondestruct. Eval."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"63","DOI":"10.1186\/s10033-021-00579-y","article-title":"Magnetic Flux Leakage Course of Inner Defects and Its Detectable Depth","volume":"34","author":"Wu","year":"2021","journal-title":"Chin. J. Mech. Eng."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"163","DOI":"10.1016\/j.measurement.2018.03.064","article-title":"A New Measurement System Using Magnetic Flux Leakage Method in Pipeline Inspection","volume":"123","author":"Ege","year":"2018","journal-title":"Measurement"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"31036","DOI":"10.3390\/s151229845","article-title":"Theory and Application of Magnetic Flux Leakage Pipeline Detection","volume":"15","author":"Shi","year":"2015","journal-title":"Sensors"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"4995","DOI":"10.1109\/JSEN.2016.2556221","article-title":"Novel Rotating Current Probe With GMR Array Sensors for Steam Generate Tube Inspection","volume":"16","author":"Ye","year":"2016","journal-title":"IEEE Sens. J."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Feng, Q., Li, R., Nie, B., Liu, S., Zhao, L., and Zhang, H. (2016). Literature Review: Theory and Application of In-Line Inspection Technologies for Oil and Gas Pipeline Girth Weld Defection. Sensors, 17.","DOI":"10.3390\/s17010050"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"108443","DOI":"10.1016\/j.measurement.2020.108443","article-title":"Magnetic Flux Detection and Identification of Bridge Cable Metal Area Loss Damage","volume":"167","author":"Ni","year":"2021","journal-title":"Measurement"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"505","DOI":"10.1784\/insi.2012.54.9.505","article-title":"Study on the Lift-off Effect on MFL Signals with Magnetic Circuit Model and 3D FEM","volume":"54","author":"Wang","year":"2012","journal-title":"Insight"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1287","DOI":"10.1007\/s12206-013-0312-7","article-title":"Jinyi Lee; Jongwoo Jun; Jungmin Kim; Minhhuy Le Electromagnetic Nondestructive Testing at High Lift-off Using a Magnetic Image Conduit","volume":"27","author":"Lee","year":"2013","journal-title":"J. Mech. Sci. Technol."},{"key":"ref_16","first-page":"1","article-title":"Highly Sensitive Magnetic Sensor Based on Anisotropic Magnetoresistance Effect","volume":"54","author":"Wang","year":"2018","journal-title":"IEEE Trans. Magn."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"683","DOI":"10.1784\/insi.2014.56.12.683","article-title":"Finite Element Model-Based Approach for Magnetic Flux Leakage Testing of Steel Plates Using 2D Tandem GMR Array Sensors","volume":"56","author":"Singh","year":"2014","journal-title":"Insight"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Mohd Noor Sam, M.A.I., Jin, Z., Oogane, M., and Ando, Y. (2019). Investigation of a Magnetic Tunnel Junction Based Sensor for the Detection of Defects in Reinforced Concrete at High Lift-Off. Sensors, 19.","DOI":"10.3390\/s19214718"},{"key":"ref_19","first-page":"1","article-title":"A Novel Electromagnetic Testing Method Based on the Magnetic Field Interaction","volume":"55","author":"Sun","year":"2019","journal-title":"IEEE Trans. Magn."},{"key":"ref_20","first-page":"44","article-title":"A Large Lift-off Nondestructive Testing Method Based on the Interaction between AC Magnetic Field and MFL Field","volume":"Volume 44","author":"Wang","year":"2019","journal-title":"Proceedings of the 23rd International Workshop on Electromagnetic Nondestructive Evaluation, ENDE 2018"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"630","DOI":"10.4028\/www.scientific.net\/KEM.270-273.630","article-title":"Numerical Consideration of Magnetic Camera for Quantitative Nondestructive Evaluation","volume":"270\u2013273","author":"Lee","year":"2004","journal-title":"KEM"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Wu, J., Fang, H., Li, L., Wang, J., Huang, X., Kang, Y., Sun, Y., and Tang, C. (2017). A Lift-Off-Tolerant Magnetic Flux Leakage Testing Method for Drill Pipes at Wellhead. Sensors, 17.","DOI":"10.3390\/s17010201"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"348","DOI":"10.1016\/j.ndteint.2010.01.005","article-title":"A New MFL Principle and Method Based on Near-Zero Background Magnetic Field","volume":"43","author":"Sun","year":"2010","journal-title":"NDT E Int."},{"key":"ref_24","unstructured":"Yilai, M., Li, L., Kaiwen, J., and Xulin, Z. (2013, January 16\u201317). The Application of Magnetic Shielding Effect in Drill Pipe Magnetic Leakage Flux Testing. Proceedings of the 2013 Fifth International Conference on Measuring Technology and Mechatronics Automation, Hong Kong, China."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Wu, J., Fang, H., Huang, X., Xia, H., Kang, Y., and Tang, C. (2017). An Online MFL Sensing Method for Steel Pipe Based on the Magnetic Guiding Effect. Sensors, 17.","DOI":"10.3390\/s17122911"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"113091","DOI":"10.1016\/j.sna.2021.113091","article-title":"A Novel Magnetic Flux Leakage Method Based on the Ferromagnetic Lift-off Layer with through Groove","volume":"332","author":"Tang","year":"2021","journal-title":"Sens. Actuators A-Phys."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"68","DOI":"10.1007\/s10921-017-0447-z","article-title":"A Permeability-Measuring Magnetic Flux Leakage Method for Inner Surface Crack in Thick-Walled Steel Pipe","volume":"36","author":"Deng","year":"2017","journal-title":"J. Nondestruct. Eval."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"54","DOI":"10.1016\/j.sna.2010.03.038","article-title":"Magnetic Compression Effect in Present MFL Testing Sensor","volume":"160","author":"Sun","year":"2010","journal-title":"Sens. Actuators A-Phys."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/9\/3587\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T23:08:06Z","timestamp":1760137686000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/9\/3587"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,5,9]]},"references-count":28,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2022,5]]}},"alternative-id":["s22093587"],"URL":"https:\/\/doi.org\/10.3390\/s22093587","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,5,9]]}}}