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    Item type:Publication,
    Sintered frictional materials based on cu powders
    (2013-10-04)
    Yodkeaw, Thanyaporn
    ;
    Tosangthum, Nattaya
    ;
    Krataitong, Rungtip
    ;
    Morakotjinda, Monnapas
    ;
    Prapai, Jirapat
    Sintered frictional materials (SFMs) were fabricated by using powder metallurgical process. Powder formulations were experimented to investigate effects of Sn, C and ZrO<inf>2</inf> additions on mechanical and tribological properties of the sintered composites made for dry frictional materials applications. The developed SFMs consisted of non-lead friction material. Natural sand (SiO<inf>2</inf>) and ZrO<inf>2</inf> were employed instead of lead oxide to provide frictional components. Interrelationships between chemical composition, sintering temperature, friction coefficient, wear behavior and mechanical property of the SFMs have been studied. It was found that sintering temperature affected hardness property of the SFMs. The hardness was also affected by SFM compositions. Friction coefficient increased with increasing ZrO<inf>2</inf> content. Addition of natural sand resulted in decrease of the hardness of the SFMs. Graphite also affected hardness and friction coefficient of SFMs containing no sand. Employing prealloyed Cu-Sn powders provided SFMs with better mechanical properties compared to the SFMs made of admixed Cu and Sn powders. © (2013) Trans Tech Publications, Switzerland.
      1
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    Item type:Publication,
    Theoretical Prediction of Journal Center Motion Trajectory in Two-Lobe Hydrodynamic Journal Bearings23
    (1995-01-01) ;
    Prabkaew, Chamlong
    ;
    Hashimoto, Hiromu
    In this study, the theoretical prediction of a journal center motion trajectory for high-speed rotors supported by two-lobe hydrodynamic oil film journal bearings is presented for three different values of the noncircular ratios, 7 = 0, 0.5 and 1.0. In order to obtain values for the oil film forces used in the equations of motion for rotor-bearing systems, the Reynolds equation governing the oil film pressure generated in the bearing gap was solved using the semianalytical finite-element method for each time step. Furthermore, for each time step, the nonlinear equations of motion for a rigid rotor supported by two identical aligned bearings were solved using the improved Euler integration method. From the numerical results, the relations between the journal center motion trajectory and the corresponding pressure distribution were examined theoretically, and the effect of the noncircular ratio on the stability of rotor bearing systems was clarified for the cases of both balanced and unbalanced rotors. © 1995, The Japan Society of Mechanical Engineers. All rights reserved.
      3
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    Item type:Publication,
    Static Characteristics of High-Speed Slider Bearings Lubricated with Non-Newtonian Fluids (In the Case of Infinitely Long Bearings)
    (1995-01-01)
    Hashimoto, Hiromu
    ;
    In this paper, the static characteristics of infinitely long slider bearings lubricated with non-Newtonian fluids are examined theoretically by considering the fluid inertia effects. In the derivation of the modified Reynolds equation, the fluid inertia terms in the momentum equation for the lubricant film are averaged over the film thickness, and the Rabinowitsch empirical model is used as a constitutive equation of non-Newtonian fluids. Applying the modified Reynolds equation to the infinitely long slider bearings, the film pressure, load carrying capacity, friction force and inlet flow rate are obtained under various values of the dimensionless nonlinear factor and film thickness ratio, and the effects of fluid inertia on these static characteristics are discussed. © 1995, The Japan Society of Mechanical Engineers. All rights reserved.
      1