1. Fractal in Surface Roughening of Sheet Metal under Uniaxial Tension, Tomoyuki TAKAYAMA*, Yasushi KUROSAKI and Masahito MATSUI: Proc. of IMMM '97, Tsu, pp. 437-­442, 1998.
   
   Free surface roughening of aluminum and killed steel sheets under uniaxial tension is examined from the viewpoint of fractal geometry. As fractal analysis methods, the power spectrum and box­counting techniques are employed and applied to surface profile curves obtained with a stylus profilometer. It is found that with an increase in plastic strain, long­wavelength components of the surface profiles become dominant, but their fractal structure (fractal dimension) tends to be constant. Based on information from the power spectrum fractal, a method for simulating the surface profile is presented and its validity confirmed. Thus, surface­roughening behaviour with an increase in plastic strain can be adequately simulated by a computer.
   
   
2. Fractal Characteristics of Free Surface Profiles of Metal Sheets under Equi-Biaxial Tension, Yasushi KUROSAKI, Masahito MATSUI, Tomoyuki TAKAYAMA* and Akira NAKANISHI*: JSME International Journal, Series C, Vol. 41, No. 3, pp. 485-492, 1998.
   
   Free surface profiles of aluminum sheets under equi-biaxial tension are examined by employing three kinds of fractal analyses, i.e., the zeroset, power spectrum and box-counting methods. With an increase in plastic strain, long-wavelength components of the surface profiles become dominant, and their fractal structure tends to become constant beyond a certain strain. It is found that both surface roughness and fractal dimensions depend on the equivalent strain, independent of the stress ratio. A method for simulating the surface roughening behavior is presented by utilizing the power spectrum method.
   
   
3. Laser Light Scattering Measurement of Lubricants at High Pressure and Evaluation of Mechanical Properties  (3rd Report, Evaluation of Shear Modulus, Refractive Index and Dynamic Density by Brillouin Scattering) [in Japanese], Yuichi NAKAMURA, Kiyoshi NISHIBE*, Osamu HAMASAKA*, Ikuya FUJISHIRO*, and Yasushi KUROSAKI : Trans. of JSME, Ser. C, 64-623, pp.2647-2652, 1998.
   
   Shear modulus, refractive index, and dynamic density of the order of GHz frequency were evaluated by measuring Brillouin scattering light under high pressure, employing a diamond-anvil high-pressure cell and a laser light scattering optical system improved on the previous one. The sound velocity on transverse mode and shear modulus were obtained for polyphenylether up to 4 GPa. The change of refractive index became small with pressure and reached to a constant value at 3 GPa. The dynamic density change by pressure was a half smaller than static one and its difference decreased with raising temperature. Application of a viscoelastic model with a bulk viscosity for these features was attempted.
   
   
4. Evaluation of Viscosity and Phase Transition on Mineral Oils up to 1.9 GPa and 150 ℃ by DAC, Yuichi NAKAMURA, Ikuya FUJISHIRO*, and Shigeaki NOMURA* : Rev. of High Pressure Sci. & Tech., Proc. of Joint AIRAPT-16&HPCJ-38 Int. Conf., Kyoto, 7, pp.1204-1206, 1998.
   
   Viscosity and phase transition for several paraffinic and naphthenic mineral oils were obtained up to 1.9 GPa and 150℃ using a diamond-anvil cell. Phase transition temperature in heating was higher than that in cooling. In the results of viscosity measurements, the differences due to chemical components (paraffinic or naphthenic) and molar weight were found out. The difference due to treating process in oil manufacture (solvent extraction or hydrotreating) was found at 1.6 GPa.
   
   
5. Evaluation of Viscosity for Synthetic Traction Oils by DAC and Traction Characteristics, Yuichi NAKAMURA, Ikuya FUJISHIRO*, Hiroyasu TSUBO*: Macro/Micro/Meso Mechanical Properties of Materials, Proc. IMMM'97, pp. 505-512, 1998.
   
   Viscosity was measured by a falling sphere method in a diamond-anvil cell (easy generating high pressure) under high pressure up to 1.4 GPa at elevated temperature up to 155 ℃ for synthetic traction oils. The obtained results showed the linearity between logarithmic viscosity and pressure, and the reduction of slope with increasing temperature was observed. The evaluation of traction characteristics near practical conditions with the obtained viscosity revealed that shear strength of lubricants such as limiting shear stress might be considered.
   
   
6. Measurement of Pressure Distribution in Pressure Media under Very High Pressure by a Diamond Anvil Cell and Evaluation of Their Friction Factor [in Japanese], Takeru NAKASHIMA*, Shuichi SATOH*, Yuichi NAKAMURA and Yasushi KUROSAKI : J. Soc. Mat. Sci., Japan (Zairyou) 47-10, pp.1019-1024, 1998.
   
   Pressure distribution under very high pressure around 5 GPa were measured employing a diamond anvil type pressure generating cell for pressure transmitting media, such as, pyrophyllite, etc, which is important in manufacturing hard materials by pressure vessel. The difference of pressure distributions among 4 kinds of pressure media were observed. The order of the magnitude of FWHM was α-Fe₂O₃＜pyrophyllite＜ NaCl＜Cu. Simulation of the obtained pressure distributions using rigid plastic FEM was succeeded on the assumption that friction factor increases following the power law of pressure. These results are expected to contribute an efficient design of a ultra-high pressure generating apparatus.

Abstracts of Books and Reviews

1.  Development of Micro-piercing Technique by Viscoplastic Pressure Medium Process [in Japanese], Yasushi KUROSAKI: Form Tech Review, Vol. 8, No. 1, pp. 22-27, 1998.
   
   Nontraditional micropiercing techniques (VIP, VM and AFM) using the viscoplastic pressure medium, developed by the author, are reviewed. In micropiercing of metal foils, various applications, an accuracy of pierced holes and an estimation method for the piercing pressure are summarized. The processes are also shown to be applicable to piercing of normal or fine holes for glass sheets.
   
   
2. Viscoelastic Properties of Lubricating Oils [in Japanese], Yuichi NAKAMURA : J. Japan Soc. of Tribologist, 36-5, pp.296-301, 1998.
   
   Viscoelastic properties of lubricating oils, which is important in elastohydrodynamic lubrication and traction drives, were described focusing high pressure and the study employing a diamond-anvil cell. Stress relaxation experiments, frequency dispersion with Brillouin light scattering technique and with ultrasonic sound velocity measurements were described.
   
   
3. Estimation of Stress Distribution of Pressure Media in a Flat Belt Type High Pressure Apparatus by the Rigid Plastic Method [in Japanese], Shuichi SATOH*, Takeru NAKASHIMA*, and Yuichi NAKAMURA : The Review of High Pressure Science and Technology, 8-4, pp.273-279, 1998.
   
   A stress distribution of pressure media in a high pressure apparatus, flat belt type, was estimated by the rigid plastic method. Since it was so difficult to estimate the stress distribution of that primarily, because of the complicated inner structure of the pressure media, we tried to estimate stress distribution in a diamond anvil cell that had a simple structure. Some of pressure media, copper, pyrophyllite and salt, were used to study the effect of friction factors. The estimated stress distribution could be equal to the observed one using the supposition of the friction factor being proportional to the 3rd power of an inner pressure. Based on the result, simulation of belt type apparatus was performed.
   
   
4. What is Hydrodynamic Lubrication ? - Image of HL, EHL, Traction - [in Japanese], Yuichi NAKAMURA : Abst. of technical lecture "Key Points of Tribology Technology", pp.601-610, 1998.
   
   Basic theories and experimental data of hydrodynamic lubrication (HL) were described.  Application of HL to journal bearings and lubrication regime, oil starvation, grease EHL in elastohydrodynamic lubrication (EHL) were also described. For traction drives, traction test machines and traction coefficients in various conditions, behaviors of traction oils at traction contact area were introduced.