1993 Fiscal Year Final Research Report Summary
Resonance method under fluid pressure to determine pressure derivatives of elastic constants and its application to the earth's interior
| Project/Area Number |
04640404
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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 |
固体地球物理学
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| Research Institution | Ehime University |
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Principal Investigator |
OHNO Ichiro Ehime Univ., Faculty of Sci., Professor, 理学部, 教授 (00116914)
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| Co-Investigator(Kenkyū-buntansha) |
HANAYAMA Yoichi Ehime Univ., Faculty of Eng., Professor, 工学部, 教授 (00036386)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Elastic constants / Pressure derivative / Renonance method / Gas pressure / Steel / Sintered material / Earth's interior |
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| Research Abstract |
1. Experiments under gas pressure and pressure derivatives of elastic constants
Measurements of cavity resonance were carried out up to 0.1GPa under helium gas pressure, using a steel sphere as test material, and pressure dependence of several toroidal (TM) and spheroidal modes (SM) were obtained. Pressure gradient of regidity was determined from TM data as dG/dP=1.80 (〕SY.+-.〔) 0.03. Pressure derivative of bulk modulus was determined from SM data as dKs/dP=4.27 (〕SY.+-.〔) 0.27, assuming the specimen-gas coupling is negligible. The determined values are very reasonable for steel, and this approves the validity of the present method of cavity resonance.
2. Measurements in water and perspective to higher pressure
It has revealed that not only TM but some SM can be detected in the measurements with the cavity filled with water at 1atm. Since the impedance of water at 1atm corresponds to that helium gas at about 1GPa, this fact gives a promising perspective to higher pressure.
3. A New data acquisition system
A new data anquistion system based on Fourier transform (FT) method (Suzuki et al., 1993) was established with a digitizing oscilloscope. It was demonstrated that spectral peaks of almost all modes can be detected with the new system.
4. Application to sintered samples
Spherical samples were prepared from polycrystalline pyrope synthesized and sintered at high temperature and high pressure, and elastic constants were determined. It was shown that we can obtain valid values of elastic constants from polycrystalline samples by preparing samples with various porosities and by extrapolating to zero porosity.
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[Publications] Suzuki, I., M.Kumazawa, Y.Inouye, I.Ohno, H.Oda, K.Sasaki, T.Sugawara, Y.Syono, H.Kumagai, and N.Suda: "Elasticity measuements on the material analogous to iron in the inner core of the earth by FT-ultrasonic spectroscopy" Conference Proceedings for the Association for the International Advancement of High Pressure. 69-72 (1993)
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