1. Fractal Characteristics of Free Surface Profile of Sheet Metals under Biaxial Tension [in Japanese], Masahito MATSUI, Yasushi KUROSAKI and Kensuke OHASHI*: Journal of the JSTP, Vol. 41, No. 478, pp. 1103-1107, 2000.
   
   The uniaxial and biaxial tension tests that cause four kinds of strain ratios are conducted on aluminum and killed steel sheets, and their free surface profiles are examined by employing fractal analysis. With an increase in plastic strain, long-wavelength components of the surface profiles become dominant, and their fractal structure tends to be constant beyond a certain strain. It is confirmed that the fractal
   dimension of surfaces is uniquely determined from the equivalent strain independently of the strain ratios, which was pointed out earlier by the authors. The fractal dimensions of newly generated surfaces of aluminum and killed steel sheets are found to be nearly equal.
   
   
2. Measurements of Sound Velocity Dispersion on Lubricants and Estimation of Volume Viscoelasticity [in Japanese], Yuichi NAKAMURA, Yasukazu TAKEUCHI* : J. Japan Soc. of Tribologist, 45-3, pp.262-269, 2000.
   
   For obtaining dynamic properties of lubricants in EHL, an ultrasonic pulse wave apparatus was established and sound velocity in MHz frequency region was measured, and that in GHz requency region was also measured employing Brillouin scattering technique for several oils such as traction fluids up to 150 ℃ at atmosphere. GHz sound velocity was resulted to be larger than MHz one at 20 ℃ (frequency dispersion), and the difference decreased with temperature and vanished at 100 ℃. Bulk modulus dispersion from sound velocity and its vanishing could be expressed by BEL viscoelastic model and by volume viscosity change with temperature. Rough estimation of bulk modulus under high pressure using BEL model, was appropriate for expressing transient region of the existing experimental data.

Abstracts of Books and Reviews

1. Sound Velocity Dispersion for Lubricant Oils in Brillouin Light Scattering and Mechanical Properties at High Pressure up to 5 GPa, Yuichi NAKAMURA, Takahiro KIYONAGA*, Ikuya FUJISHIRO* and Yasushi KUROSAKI, Synopses of International Tribology Conference, Nagasaki, p.128, 2000.
   
   Using Brillouin light scattering technique, frequency dispersions of sound velocity (about 7 % increase) for some lubricant oils were obtained at atmospheric pressure with varying frequency ( from about 5 GHz to 10 GHz). The dispersions seemed to be induced by the viscosity and viscoelastic effect. The dispersion disappeared at high pressure immediately in a diamond-anvil high-pressure cell (DAC) device and the disappearance maintained up to 5 GPa in loading process. In unloading process, unpredictable large difference of sound velocity in orthogonal directions was observed. Hysteresis between loading and unloading may bring some influence on solidified oil film under Hertzian pressure profile. Dispersion of elastic modulus at high pressure was also evaluated based on reference data.
   
   
2. Laser Light Scattering Measurement of Lubricants at High Pressure and Evaluation of Mechanical Properties  (4th Report, Evaluation of High Viscosity of Solidfied Lubricants by Rayleigh Scattering and Photon Correlation Technique) [in Japanese], Yuichi NAKAMURA, Masayuki TSUNODA*, Tatsuya MATSUI*, and Ikuya FUJISHIRO* : Report of JSME Awards, J. of JSME, 103, 978, pp.286, 2000.
   
   Authors received JSME Award for a paper and its content is as follows. A new viscosity measuring system was designed and set up employing Rayleigh light scattering and a photon correlation technique using a diamond-anvil high-pressure cell. Two kinds of experiments were attempted. The one was the measurement for dilute suspensions of polystyrene latex spheres in liquid lubricants and a W/O emulsion. The other experiment was the measurement for 5P4E (polyphenyl ether) and DOP (dioctylphthalate) without mixing polystyrene spheres. Very weak but observable correlation functions concerning structural relaxation were observed and the viscosities of solidified lubricants (about 10⁹ Pa･s), obtained in very short time, were consistent with data of falling body method.