Defect evaluation in mild steel plate using harmonic ratio induced by square wave excitation field and nonlinear magnetization
Similar to multi-frequency techniques in eddy current and magnetic flux leakage testings, the harmonic evaluation technique using a square wave excitation field improves the defect detection performance of conductive materials compared to single-frequency techniques. However, in the case of mild ste...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English English |
| Published: |
Institute of Electrical and Electronics Engineers Inc.
2024
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| Subjects: | |
| Online Access: | http://umpir.ump.edu.my/id/eprint/42134/ http://umpir.ump.edu.my/id/eprint/42134/1/Defect%20evaluation%20in%20mild%20steel%20plate%20using%20harmonic%20ratio.pdf http://umpir.ump.edu.my/id/eprint/42134/2/Defect%20evaluation%20in%20mild%20steel%20plate%20using%20harmonic%20ratio%20induced%20by%20square%20wave%20excitation%20field%20and%20nonlinear%20magnetization_ABS.pdf |
| Summary: | Similar to multi-frequency techniques in eddy current and magnetic flux leakage testings, the harmonic evaluation technique using a square wave excitation field improves the defect detection performance of conductive materials compared to single-frequency techniques. However, in the case of mild steel, its nonlinear frequency-dependant magnetization impacts the intensity and phase of the induced harmonics. In this work, we propose a harmonic ratio technique using a square wave excitation field to enhance defect detection in mild steel. A custom-made probe with a planar differential tunnel magnetoresistance sensor and inductor arrays was developed to assess the harmonic responses induced by artificial slits on a 12-mm mild steel. The harmonic dependency on the slit depth, excitation frequency, and intensity was evaluated. The results showed that the ratio of the two highest harmonics exhibited a correlation with slit depth, accompanied by a significant reduction in baseline signal drift as compared to the single-frequency detection mode. It was shown that the proposed harmonic ratio technique, leveraging a square wave excitation field, significantly enhances sensitivity and immunity to background signal drift, thereby improving defect detection capabilities in mild steel. |
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