{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,16]],"date-time":"2025-10-16T03:55:59Z","timestamp":1760586959947,"version":"build-2065373602"},"reference-count":16,"publisher":"MDPI AG","issue":"13","license":[{"start":{"date-parts":[[2019,7,8]],"date-time":"2019-07-08T00:00:00Z","timestamp":1562544000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100002241","name":"Japan Science and Technology Agency","doi-asserted-by":"publisher","award":["Strategic Innovation Promotion Program"],"award-info":[{"award-number":["Strategic Innovation Promotion Program"]}],"id":[{"id":"10.13039\/501100002241","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Conventional eddy current testing (ECT) using a pickup coil probe is widely employed for the detection of structural cracks. However, the inspection of conventional ECT for steel structures is difficult because of the magnetic noise caused by the nonuniform permeability of steel. To combat this challenge, we have developed a small magnetic sensor probe with a dual-channel tunneling magnetoresistance sensor that is capable of reducing magnetic noise. Applying this probe to a complicated component of steel structures\u2014such as the welds joining a U-shaped rib and deck plate together\u2014requires the reduction of signal fluctuation caused by the distance (liftoff) variations between the sensor probe and the subject. In this study, the fundamental crack signal and the liftoff signal were investigated with the dual-channel sensor. The results showed that the liftoff signals could be reduced and differentiated from the crack signals by the differential parameters of the dual-channel sensor. In addition, we proposed an extraction technique for the crack signal using the Lissajous curve of the differential parameters. The extraction technique could be applied to the inspections not only for flat plates but also for welded angles to detect cracks without the influence of the liftoff signal.<\/jats:p>","DOI":"10.3390\/s19133001","type":"journal-article","created":{"date-parts":[[2019,7,8]],"date-time":"2019-07-08T03:01:31Z","timestamp":1562554891000},"page":"3001","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Extraction Method of Crack Signal for Inspection of Complicated Steel Structures Using A Dual-Channel Magnetic Sensor"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1525-894X","authenticated-orcid":false,"given":"Minoru","family":"Hayashi","sequence":"first","affiliation":[{"name":"Graduate School of Interdisciplinary Science and Engineering in Health Systems; Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Taisuke","family":"Saito","sequence":"additional","affiliation":[{"name":"Graduate School of Interdisciplinary Science and Engineering in Health Systems; Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yoshihiro","family":"Nakamura","sequence":"additional","affiliation":[{"name":"Graduate School of Natural Science and Technology; Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kenji","family":"Sakai","sequence":"additional","affiliation":[{"name":"Graduate School of Interdisciplinary Science and Engineering in Health Systems; Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Toshihiko","family":"Kiwa","sequence":"additional","affiliation":[{"name":"Graduate School of Interdisciplinary Science and Engineering in Health Systems; Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Izumi","family":"Tanikura","sequence":"additional","affiliation":[{"name":"Japan Construction Method and Machinery Research Institute, 3154 Obuchi, Fuji city, Shizuoka 417-0801, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Keiji","family":"Tsukada","sequence":"additional","affiliation":[{"name":"Graduate School of Interdisciplinary Science and Engineering in Health Systems; Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2019,7,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1155\/2014\/182496","article-title":"Defect Characterization Based on Eddy Current Technique: Technical Review","volume":"6","author":"Ghoni","year":"2014","journal-title":"Adv. Mech. Eng."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2525","DOI":"10.3390\/s110302525","article-title":"Non-Destructive Techniques Based on Eddy Current Testing","volume":"11","author":"Gil","year":"2011","journal-title":"Sensors"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1568","DOI":"10.1109\/JSEN.2017.2782799","article-title":"Low-Frequency Eddy-Current Testing for Detection of Subsurface Cracks in CF-188 Stub Flange","volume":"18","author":"Alatawneh","year":"2018","journal-title":"IEEE Sens. J."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"406","DOI":"10.1016\/j.proeng.2014.11.054","article-title":"Present and Future Impact of Magnetic Sensors in NDE","volume":"86","author":"Ramos","year":"2014","journal-title":"Procedia Eng."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Rifai, D., Abdalla, A.N., Ali, K., and Razali, R. (2016). Giant Magnetoresistance Sensors: A Review on Structures and Non-Destructive Eddy Current Testing Applications. Sensors, 16.","DOI":"10.3390\/s16030298"},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Bailey, J., Long, N., and Hunze, A. (2017). Eddy Current Testing with Giant Magnetoresistance (GMR) Sensors and a Pipe-Encircling Excitation for Evaluation of Corrosion under Insulation. Sensors, 17.","DOI":"10.3390\/s17102229"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"3315","DOI":"10.1109\/TMAG.2006.879754","article-title":"Low-Frequency Eddy Current Imaging Using MR Sensor Detecting Tangential Magnetic Field Components for Nondestructive Evaluation","volume":"42","author":"Tsukada","year":"2006","journal-title":"IEEE Trans. Magn."},{"key":"ref_8","first-page":"86","article-title":"Usage of Magnetic Field Sensors for Low Frequency Eddy Current Testing","volume":"5","author":"Hesse","year":"2005","journal-title":"Meas. Sci. Rev."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"323","DOI":"10.1016\/j.ndteint.2010.01.004","article-title":"Detection of back-side pit on a ferrous plate by magnetic flux leakage method with analyzing magnetic field vector","volume":"43","author":"Tsukada","year":"2010","journal-title":"NDT E Int."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1109\/TMAG.2017.2713880","article-title":"Detection of Inner Cracks in Thick Steel Plates Using Unsaturated AC Magnetic Flux Leakage Testing With a Magnetic Resistance Gradiometer","volume":"53","author":"Tsukada","year":"2017","journal-title":"IEEE Trans. Magn."},{"key":"ref_11","first-page":"1","article-title":"Small Eddy Current Testing Sensor Probe Using a Tunneling Magnetoresistance Sensor to Detect Cracks in Steel Structures","volume":"54","author":"Tsukada","year":"2018","journal-title":"IEEE Trans. Magn."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1362","DOI":"10.1109\/TIM.2010.2043981","article-title":"Liftoff Correction Based on the Spatial Spectral Behavior of Eddy-Current Images","volume":"59","author":"Ribeiro","year":"2010","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"167","DOI":"10.1109\/TIM.2017.2728338","article-title":"Reducing the Lift-Off Effect on Permeability Measurement for Magnetic Plates from Multifrequency Induction Data","volume":"67","author":"Lu","year":"2018","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"43","DOI":"10.1016\/j.ndteint.2016.10.001","article-title":"Evaluation of the lift-off robustness of eddy current imaging techniques","volume":"85","author":"Ricci","year":"2017","journal-title":"NDT E Int."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"821","DOI":"10.1109\/TIM.2018.2792848","article-title":"Fast Eddy Current Testing Defect Classification Using Lissajous Figures","volume":"67","author":"Laracca","year":"2018","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_16","unstructured":"Hayashi, M., Nakamura, Y., Sakai, K., Kiwa, T., and Tsukada, K. (2018, January 12\u201315). Detection method using a dual-channel magnetic sensor for steel cracks in complicated structures. Proceedings of the 7th Asia-Pacific Workshop on Structural Health Monitoring (APWSHM-2018), Hong Kong, China."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/13\/3001\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T13:03:28Z","timestamp":1760187808000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/13\/3001"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,7,8]]},"references-count":16,"journal-issue":{"issue":"13","published-online":{"date-parts":[[2019,7]]}},"alternative-id":["s19133001"],"URL":"https:\/\/doi.org\/10.3390\/s19133001","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2019,7,8]]}}}