| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Isao Okayama Univ., Dept.Earth Sci., Professor, 理学部, 教授 (60033198)
KIMURA Masaki Ehime Univ., Dept.Material Sci.Eng., Assistant Prof., 工学部, 助手 (50127891)
HANAYAMA Yoichi Ehime Univ., Dept.Material Sci.Eng., Professor, 工学部, 教授 (00036386)
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| Research Abstract |
A new data acquisition method, FT method, in the resonance method was put into practical use, where impulse input is fed to the sample and the respondent wave form is acquired as digital time series data, and the spectrum is obtained as Fourie transform. It was found the sinx/x-type impulse with suitable pulse width yields desirable spectra.
For a spherical sample of steel with the sample-gas-cavity container assembly, the pressure changes of eigenfrequencies were measured up to 100MPa under helium gas pressure. The data of pressure derivative of frequency, *f/*P,were obtained for three toroidal modes, 0T4,1T1 and 0T5, and three spheroidal modes, 1S2,1S3 and 1S4. The *f/*P's of toroidal modes yields immediately the pressure derivative of rigidity, G_0'=2.0 (1).
In order to reduce the pressure derivative of bulk modulus K_0' from *f/*P of spheroidal modes, the sample-gas-cavity container system was regarded as a spherical three-layd structure, and the eigenfrequencies were computed as a function of pressure by means of DISPER80 (Saito, 1988), asuuming various values of K_0'. Comparing the computed *f/*P with the measured one, we have K_0'=8-9. This is twice as large as the value K_0'=4-5 which was reduced by neglecting the coupling between the spheroidal modes and the soundings. This result demonstrates that it is necessary to treat the sample assembly as a spherical three-layrd structure in the reduction of K_0'from *f/*P of spheroidal modes. Through the present achievement to reduce K_0', the cavity resonance method has been established as a new method to measure pressure derivatives of elastic moduli of isotropic solids.
Elastic properties of rare gases and WC alloys, the pressure medium and the material of the cavity container, were measure under pressure and used in the present analysis of spheroidal modes.
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