| Project/Area Number |
11650439
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Measurement engineering
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| Research Institution | Oita National College of Technology |
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Principal Investigator |
OKA Mohachiro Oita National College of Technology, Department of Computer and Control Engineering, Associate Professor, 制御情報工学科, 助教授 (80107838)
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| Co-Investigator(Kenkyū-buntansha) |
ENOKIZONO Masato Oita University, Faculty of Engineering, Department of Electric and Electronics Engineering, Professor, 工学部・電気電子工学科, 教授 (40136784)
KANADA Tsugunori Oita National College of Technology, Department of Computer and Control Engineering, Professor, 制御情報工学科, 教授 (70040756)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2000: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1999: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Keywords | Non-destructive evaluation / Magnetic sensor / Hybrid magnetic sensor / Fatigue / Bending stress / Natural crack / MI element / FG magnetic sensor / 勾配磁気センサ / 渦電流 / 裏側欠陥 / 欠陥属性推定 |
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| Research Abstract |
In this project, we developed the non-destructive evaluation system used the hybrid magnetic sensor for natural cracks on a reverse-side of thick metallic plates. The hybrid magnetic sensor consists of a gradio-magneto sensor and an exciting system. This new hybrid magnetic sensor using MI elements shows high sensitivity and stability. On the other hand, in order to estimate the amount of bending fatigue damage on austenitic stainless steel plates, we have investigated the relationship between plane bending stress and residual magnetization caused by martensitic structure in austenitic stainless steel plates. Magnetic flux density in the Z component caused by residual magnetization at 1 mm above a specimen is measured by using a high sensitivity thin-film flux-gate magnetic sensor. It can detect a very small magnetic flux density. From our experiments, the magnetic flux density at 1 mm above a specimen caused by residual magnetization has clear dependences on the increase of bending st
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ress and the number of stress cycles. Results of this project are shown as follows :
1) The hybrid magnetic sensor with a U-shaped exciting core made of laminated silicon steel plate clearly detect a 1 mm depth, 5 mm length, 0.5 mm width reverse-side defect on a 5 mm thick steel plate.
2) The hybrid magnetic sensor with a U-shaped exciting core made of ferrite can clearly detect a 1 mm depth reverse-side defect on a 5 mm thick stainless steel plate.
3) The change of the Z component of the magnetic flux density (δB_z) clearly increases with increase in the bending stress and the number of stress cycles. The value of δB_z depends on the bending stress.
4) The value of δBz (=B_<zmax>-B_<zmin>). obviously depends on the bending stress.
5) The residual magnetization in austenitic stainless steel plates depends on the amount of the bending fatigue damage.
6) If the bending stress is less than the fatigue limit, martensitic structure in austenitic stainless steel plates is gradually induced by the cyclic bending stress.
7) Martensite transformation is induced even over 1.0x10^7 cycles of bending, less than the fatigue limit. Less
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