2004 Fiscal Year Final Research Report Summary
Development of Nondestructive Evaluation System Using the Excitation Type High Sensitivity Magnetic Sensor to Ddetect Fatigue Damage of Metallic Material
| Project/Area Number |
15560371
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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, Professor, 制御情報工学科, 教授 (80107838)
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| Co-Investigator(Kenkyū-buntansha) |
KANADA Tsugunori Oita National College of Technology, Department of Computer and Control Engineering, Professor, 制御情報工学科, 教授 (70040756)
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)
YAKUSHIJI Terutoshi Oita National College of Technology, Department of Mechanical Engineering, Professor, 機械工学科, 教授 (90210228)
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| Project Period (FY) |
2003 – 2004
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| Keywords | Non-destructive Evaluation / Excitation Type Magnetic Sensor / SUS304 / SUS316 / Austenite / Martensite / Bending Stress / Fatigue Damage |
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| Research Abstract |
In this project, we have elucidated the following results for the evaluation of fatigue damage in an austenitic stainless steel using the FG magnetic sensor and we developed the non-destructive evaluation system using the excitation type high sensitivity magnetic sensor to detect fatigue damage of metallic material.
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.
The eddy current probe which is a new magnetic sensor to detect fatigue damage on austenitic stainless steels consists of an excitation coil and two pick-up coils wound on a ferrite core. The size of the EC probe is 10 mm x 4 mm x 8 mm.
Results of this project are shown as follows:
1) The value of B_<zmax> clearly increases with the increase of the bending stress (σ_a) and N.
2) The value of B_<zmax> is a useful parameter to estimate the amount of fatigue damage.
3) We could detect the small leakage magnetic flux density on the specimens such as SUS304, SUS304L, SUS316 and SUS316L caused by the residual magnetization by using the FG magnetic sensor.
4) The residual magnetization in SUS316 series is about ten times smaller than SUS304 series.
5) This new eddy current probe was surely able to catch the change in electromagnetic properties such as magnetic permeability caused by the transformation from austenite to martensite in SUS304.
6) The value of Rc_<max> obviously depends on the number of stress cycles.
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