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  • Other Sources  (8)
  • 1
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    Thermal elastohydrodynamic lubrication of line contacts (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A numerical solution to the problem of thermal elastohydrodynamic lubrication of line contacts was obtained by using a finite difference formulation. The solution procedure consists of simultaneous solution of the thermal Reynolds equation, the elasticity equation, and the energy equation subject to appropriate boundary conditions. Pressure distribution, film shape, and temperature distribution were obtained for fully flooded conjunctions, a paraffinic lubricant, and various dimensionless speed parameters while the dimensionless load and materials parameters were held constant. Reduction in the minimum film thickness due to thermal effects (as a ratio of thermal to isothermal minimum film thickness) is given by a simple formula as a function of the thermal loading parameter Q: H(min)/H(min, I) = 10/10 + Q(0.4). Plots of pressure distribution, film shape, temperature distribution, and flow are shown for some representative cases.
    Keywords: MECHANICAL ENGINEERING
    Type: ASLE Transactions; 28; 159-169;
    Format: text
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  • 2
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    Starvation effects on the hydrodynamic lubrication of rigid nonconformal contacts in combined rolling and normal motion (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The effect of inlet starvation on the hydrodynamic lubrication of lightly loaded rigid nonconformal contacts in combined rolling and normal motion is determined through a numerical solution of the Reynolds' equation for an isoviscous, incompressible lubricant. Starvation is effected by systematically reducing the fluid inlet level. The pressures are taken to be ambient at the inlet meniscus boundary and Reynolds' boundary condition is applied for film rupture in the exit region. Results are presented for the dynamic performance of the starved contacts in combined rolling and normal motion for both normal approach and separation. During normal approach the dynamic load ratio (i.e. ratio of dynamic to steady state load capacity) increases considerably with increase in the inlet starvation. The effect of starvation on the dynamic peak pressure ratio is relatively small. Further, it has been observed that with increasing starvation, film thickness effects become significant in the dynamic behavior of the nonconformal contacts. For significantly starved contacts the dynamic load ratio increases with increase in film thickness during normal approach and a similar reduction is observed during separation. A similar effect is noted for the dynamic peak pressure ratio.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ASLE Transactions (ISSN 0569-8197); 30; 91-99
    Format: text
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  • 3
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    Starvation effects on the hydrodynamic lubrication of rigid nonconformal contacts in combined rolling and normal motion (1986)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The effect of inlet starvation on the hydrodynamic lubrication of lightly loaded rigid nonconformal contacts in combined rolling and normal motion is determined through a numerical solution of the Reynolds' equation for an isoviscous, incompressible lubricant. Starvation is effected by systematically reducing the fluid inlet level. The pressures are taken to be ambient at the inlet meniscus boundary and Reynolds' boundary condition is applied for film rupture in the exit region. Results are presented for the dynamic performance of the starved contacts in combined rolling and normal motion for both normal approach and separation. During normal approach the dynamic load ratio (i.e. ratio of dynamic to steady state load capacity) increases considerably with increase in the inlet starvation. The effect of starvation on the dynamic peak pressure ratio is relatively small. Further, it has been observed that with increasing starvation, film thickness effects become significant in the dynamic behavior of the nonconformal contacts. For significantly starved contacts the dynamic load ratio increases with increase in film thickness during normal approach and a similar reduction is observed during separation. A similar effect is noted for the dynamic peak pressure ratio.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-87174 , E-2817 , NAS 1.15:87174 , USAAVSCOM-TR-85-C-20
    Format: application/pdf
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  • 4
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    Hydrodynamic lubrication of rigid nonconformal contacts in combined rolling and normal motion (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A numerical solution to the problem of hydrodynamic lubrication of rigid point contacts with an isoviscous, incompressible lubricant was obtained. The hydrodynamic load-carrying capacity under unsteady (or dynamic) conditions arising from the combined effects of squeeze motion superposed upon the entraining motion was determined for both normal approach and separation. Superposed normal motion considerably increases net load-carrying capacity during normal approach and substantially reduces net load-carrying capacity during separation. Geometry was also found to have a significant influence on the dynamic load-carrying capacity. The ratio of dynamic to steady state load-carrying capacity increases with increasing geometry parameter for normal approach and decreases during separation. The cavitation (film rupture) boundary is also influenced significantly by the normal motion, moving downstream during approach and upstream during separation. For sufficiently high normal separation velocity the rupture boundary may even move upstream of the minimum-film-thickness position. Sixty-three cases were used to derive a functional relationship for the ratio of the dynamic to steady state load-carrying capacity in terms of the dimensionless normal velocity parameter (incorporating normal velocity, entraining velocity, and film thickness) and the geometry parameter.
    Keywords: MECHANICAL ENGINEERING
    Type: ASME PAPER 84-TRIB-13 , ASME, Transactions, Journal of Tribology (ISSN 0742-4787); 107; 97-103
    Format: text
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  • 5
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    Remote Pulsed-Laser Raman Spectroscopy System for Mineral Analysis (2001)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: We have measured Raman spectra of carbonate, silicate, and hydrous silicate and sulfate minerals, our new remote-pulsed Raman system, indicating that it can be used to analyze the minerals on planetary surfaces to a distance of 10 to 66 meters. Additional information is contained in the original extended abstract.
    Keywords: Lunar and Planetary Science and Exploration
    Type: Lunar and Planetary Science XXXII; LPI-Contrib-1080
    Format: text
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  • 6
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    Thermal elastohydrodynamic lubrication of line contacts (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A numerical solution to the problem of thermal elastohydrodynamic lubrication of line contacts was obtained by using a finite difference formulation. The solution procedure consists of simultaneous solution of the thermal Reynolds equation, the elasticity equation, and the energy equation subject to appropriate boundary conditions. Pressure distribution, film shape, and temperature distribution were obtained for fully flooded conjunctions, a paraffinic lubricant, and various dimensionless speed parameters while the dimensionless load and materials parameters were held constant. Reduction in the minimum film thickness due to thermal effects (as a ratio of thermal to isothermal minimum film thickness) is given by a simple formula as a function of the thermal loading parameter Q: H(min)/H(min,I) = 10/10+ Q(0.4). Plots of pressure distribution, film shape, temperature distribution, and flow are shown for some representative cases.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-83424 , E-1617 , NAS 1.15:83424
    Format: application/pdf
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  • 7
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    A Combined Remote LIBS and Raman Spectroscopic Study of Minerals (2002)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: In this paper, we explore the use of remote LIBS combined with pulsed-laser Raman spectroscopy for mineral analysis at a distance of 10 meters. Samples analyzed include: carbonates (both biogenic and abiogenic), silicates, and sulfates. Additional information is contained in the original extended abstract.
    Keywords: Lunar and Planetary Science and Exploration
    Type: Lunar and Planetary Science XXXIII; LPI-Contrib-1109
    Format: text
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  • 8
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    Hydrodynamic lubrication of rigid nonconformal contacts in combined rolling and normal motion (1984)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A numerical solution to the problem of hydrodynamic lubrication of rigid point contacts with an isoviscous, incompressible lubricant was obtained. The hydrodynamic load-carrying capacity under unsteady (or dynamic) conditions arising from the combined effects of squeeze motion superposed upon the entraining motion was determined for both normal approach and separation. Superposed normal motion considerably increases net load-carrying capacity during normal approach and substantially reduces net load-carrying capacity during separation. Geometry was also found to have a significant influence on the dynamic load-carrying capacity. The ratio of dynamic to steady state load-carrying capacity increases with increasing geometry parameter for normal approach and decreases during separation. The cavitation (film rupture) boundary is also influenced significantly by the normal motion, moving downstream during approach and upstream during separation. For sufficiently high normal separation velocity the rupture boundary may even move upstream of the minimum-film-thickness position. Sixty-three cases were used to derive a functional relationship for the ratio of the dynamic to steady state load-carrying capacity in terms of the dimensionless normal velocity parameter (incorporating normal velocity, entraining velocity, and film thickness) and the geometry parameter.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-83578 , E-1926 , NAS 1.15:83578 , AVRADCOM-TR-84-C-2 , Joint Lubrication Conf.; Oct 22, 1984 - Oct 24, 1984; San Diego, CA; United States
    Format: application/pdf
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