1995 Fiscal Year Final Research Report Summary
Nondestructive Estimation of Stress and flaws by combining Magnetic Field and Ultrasonics
| Project/Area Number |
06650105
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Materials/Mechanics of materials
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
MATSUMOTO Eiji Kyoto University, Graduate School of Engineering, Assoc.Professor, 工学研究科, 助教授 (30093313)
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| Co-Investigator(Kenkyū-buntansha) |
MOTOGI Shinya Osaka City University, Graduate School of Engineering, Assoc.Professor, 工学部, 助教授 (40221626)
SHIBATA Toshinobu Kyoto University, Graduate School of Engineering, Professor, 工学研究科, 教授 (40025929)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Acoustoelasticity / Magnetoacoustoelasticity / Stress Measurements / Nondestructive Evaluation / Magnetic Materials / Ultrasonic Waves / Magnetoelasticity / Magnetoacoustic Emission |
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| Research Abstract |
The purpose of the subject is to develop the magnetoacoustic nondestructive techniques proposed by the investigators in order to include the cases of strong stresses and fractures. The obtained result during the term of the project is the followings.
1. Stress evaluation by Magnetoacoustoelasticity
We showed that it is possible to separate the texture and the acoustic anisotropy in the speed change of ultrasonic waves by applying a suitable magnetic field. We proposed new technique of plane stress evaluation only by longitudinal waves by choosing the applied magnetic field.
2. Magnetoacoustic Emission (MAE) under the stress
We applied the stress to the magnetic material (low carbon steel) up to the plastic region, and measured MAE at each stress level under the periodic change of the magnetic field. The total count of MAE signals during one cycle of the magnetic field, is found to decrease according to the stress in the elastic region. In a result, the nondestructive evaluation of the stress using MAE is suitable for low stress levels in the elastic region. In addition to the extension test, we also measured the stress dependence of MAE under compression test. It is shown that the MAE count during one cycle of the magnetic field is symmetry with respect to the sign of the uniaxial stress. Possibility of flaw estimation by MAE is left as a future subject.
3. Constitutive Equations of the magnetic materials
As for the rate dependence of the magnetization, we proposed a rate type constitutive equation and verified that the indential response of the magnetization agrees with the experimental data. We also created the experimental instrument of two-dimensional magnetization tests. We showed that the proposed three-dimensional constitutive equations with nonlinear, anisotropic and hysteretic effects well describes the experimental results of magnetization under rotating magnetic field.
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