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REFINED MATHEMATICAL MODEL OF A BINARY GAS BEARING IN WIDE RANGE OF KNUDSEN NUMBERS
Drozdov, Y.N.,Yemelyanov, I.A. 경북대학교 트라이볼로지연구소 2001 INTERNATIONAL SYMPOSIUM ON HIGH PERFORMANCE OF TRI Vol.2001 No.-
The experimental technique for high strength yarn's cut resistance measurement was proposed Transverse cut tests at various angles of cutter blade inclination were performed on Zylon, Kevlar and Spectra yarns to evaluate the cut resistance of high strength fabrics and to investigate the failure mechanism involved in the cutting process. The effects of blade angle of inclination on the yarn's cut resistance were presented. In tests with a utility blade ( 2 ㎛ radius of curvature), Zylon required 4 times as much energy per linear density than other two materials, for cut-through at 0° angle of inclination. This fracture energy decreased sharply with increased inclination angle, as did the strain corresponding to the initiation of fiber failure.
NEW EVALUATION METHOD FOR SURFCE ENERGY WITH μm SIZE LIQUID DROPLETS
Umehara, N.,Yamaguchi, uichiro,Kato, Koji 경북대학교 트라이볼로지연구소 2001 INTERNATIONAL SYMPOSIUM ON HIGH PERFORMANCE OF TRI Vol.2001 No.-
New evaluation method of surface energy with an ESEM was proposed. In this method, condensed liquid droplets were used for the measurement of contact angle. Two different contact angles with water and diiodemethane droplets on the specimen provided surface energy of the specimen. The surface energy obtained with this method is the same as the values by the conventional method with micro-syringe. Therefore, this method can use for the evaluation of the surface energy. Contact angles of water droplets are independent of the diameter of the droplets. On the other hand, contact angles of diiodemethane decrease with diameter of that if the diameter is more than 100μm.
DYNAMIC MODELING OF FRICTION CHARACTERISTIC BETWEEN PILE AND SOIL
TUAN, NGUYEN ANH,NGAN, NGUYEN HONG 경북대학교 트라이볼로지연구소 2001 INTERNATIONAL SYMPOSIUM ON HIGH PERFORMANCE OF TRI Vol.2001 No.-
The mechanical properties, fracture behaviors and micro-mechnism of damage have been studied for three spheroidized steels. It is shown that void formation and growth induced by decohesion at the interface between the ferrite matrix and non-metallic particles or by particle cracking are the main reasons for the failure of these materials during plastic deformation. Experimental results show that the void volume fractions of these materials increase as strain increases, with the increasing rate being larger for the material with more carbide particles. Analytical expressions of strain hardening exponent and fracture strain for plastically damaged materials with second-phase particles are derived, and shown to be in good agreement with experimental data.
Damage and Fracture for Spheroidized Steels during Uniaxial Tensile Testing
Zhou, Fei.,Suh, Chang-Min,Kim, Seock-Sam 경북대학교 트라이볼로지연구소 2001 INTERNATIONAL SYMPOSIUM ON HIGH PERFORMANCE OF TRI Vol.2001 No.-
The mechanical properties, fracture behaviors and micro-mechnism of damage have been studied for three spheroidized steels. It is shown that void formation and growth induced by decohesion at the interface between the ferrite matrix and non-metallic particles or by particle cracking are the main reasons for the failure of these materials during plastic deformation. Experimental results show that the void volume fractions of these materials increase as strain increases, with the increasing rate being larger for the material with more carbide particles. Analytical expressions of strain hardening exponent and fracture strain for plastically damaged materials with second-phase particles are derived, and shown to be in good agreement with experimental data.
Study of High Definition Thermal Transfer Ink Ribbon
HIBINO, Ikuo 경북대학교 트라이볼로지연구소 2001 INTERNATIONAL SYMPOSIUM ON HIGH PERFORMANCE OF TRI Vol.2001 No.-
Analysis was made of the thermal transfer printing process and 600-dpi high-definition thermal transfer ink ribbons. The results of analysis of this printing process revealed that four factors would play an important role in high-definition thermal transfer ink ribbons: (1) enough rupture strength of ink under printing pressure, (2) adhesive strength of ink and paper, (3) thinning of the ink layer and (4) adhesive strength between the heated part of ink and the basefilm. Using 2.5 ㎛-thick PET film as the basefilm, a 600-dpi high-definition thermal transfer ink ribbon has been developed, with a 1.3 ㎛-thick thermoplastic resin layer based on ethylene-vinyl acetate copolymer superimposed on a 0.9 ㎛-thick wax layer. The ink transfer properties of the ink ribbon were evaluated using a pendulum-type viscoelastic properties measuring instrument, with attention focused on the logarithmic decrement -temperature property.
Antioxidation action of ZnDDP blended with MoDDP in mineral oil
Da-Chang Du,Kim, Seock-Sam,Chun, Jung-Sik,Suh, Chang-Min,Kwon, Wan-Seop 경북대학교 트라이볼로지연구소 2001 INTERNATIONAL SYMPOSIUM ON HIGH PERFORMANCE OF TRI Vol.2001 No.-
The flow analyzed is that of viscous gas within a clearance of binary thrust bearing with spiral grooves having identical geometry at both working surfaces. The boundary conditions for velocity take into account the slip effects of the first and second orders according to Cercignani-Sliozkin method. The essentially nonlinear equation is obtained for determination of dominating pressure in active zone of binary models; the equation is fit for a wide range of Knudsen numbers. The algorithms are developed for calculation of the integral characteristics of binary thrust bearing. The refined data are presented concerning the optimal parameters and advantages of binary bearings. According to the optimization data the computational tables are constructed which permit to realize the design of the experimental models of binary thrust bearing without additional calculations.
IWABUCHI, AKIRA 경북대학교 트라이볼로지연구소 2001 INTERNATIONAL SYMPOSIUM ON HIGH PERFORMANCE OF TRI Vol.2001 No.-
In this paper, I would like to introduce the summary of the national research project on Next Generation Manufacturing and Production Process of Dies, sponsored by NEDO, Japanese Government from October, 1998 to March, 2000. We thought that the die production technology is the key to maintain the high level of Japanese industries. The project consisted of five research groups of die design technology, super-precision machining, corrosion protection in EDM, mold releasing agent, and production processes, and totally 19 sub-themes were carried out. We tried to confirm the performance of new polishing methods, and made new truing tool of profile-grinding. In relation to tribology, we tried to understand the wear mechanism of cemented carbide during operation against soft metals.
Residual Stress and Fatigue Characteristics in Ceramic Coatings Produced by PVD
Suh, Chang-Min,Hwang, Byung-Won,Kim, Sung-Ho 경북대학교 트라이볼로지연구소 2000 INTERNATIONAL SYMPOSIUM ON HIGH PERFORMANCE OF TRI Vol.2001 No.-
The residual stress of TiN and TiAlN ceramic coatings that were coated on 1Cr-1Mo-0.25V steels was measured using the X-ray diffraction method. The ceramic coatings were deposited by arc-ion plating. The behavior of the compressive residual stress formed in the coated layer was investigated before and after stress-relief heat treatment. In order to establish the relationship between fatigue strength and residual stress, fatigue tests of the TiAlN-coated and uncoated specimens were performed at room and elevated temperatures. The effect of hardness on the fatigue characteristics was also investigated. As a result, it was apparent that compressive residual stress has an effect on increasing the fatigue strength.
EXAMINATION OF THE FRICTION FORCE IN PNEUMATIC CYLINDERS
TUAN, NGUYEN ANH,TRUONG, NGUYEN MINH 경북대학교 트라이볼로지연구소 2001 INTERNATIONAL SYMPOSIUM ON HIGH PERFORMANCE OF TRI Vol.2001 No.-
The frictional force inside pneumatic cylinders has a significant influence on the motion characteristics of the pneumatic cylinder transmission. Therefore, it's very difficult to determine this force, especially at high speed and high acceleration of the piston. In this paper, a dynamic method to determine the friction force in pneumatic cylinders is described.