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RESEARCH PAPERS

A New Model of Thermoelastohydrodynamic Lubrication in Dynamically Loaded Journal Bearings

[+] Author and Article Information
Aurelian Fatu

Laboratoire de Mécanique des Solides, Université de Poitiers, UMR CNRS 6610, 4, Avenue de Varsovie, 16021 Angoulême Cedex, Franceafatu@iutang.univ-poitiers.fr

Mohamed Hajjam, Dominique Bonneau

Laboratoire de Mécanique des Solides, Université de Poitiers, UMR CNRS 6610, 4, Avenue de Varsovie, 16021 Angoulême Cedex, France

J. Tribol 128(1), 85-95 (Aug 17, 2005) (11 pages) doi:10.1115/1.2114932 History: Received February 28, 2005; Revised August 17, 2005

A comprehensive method of thermoelastohydrodynamic (TEHD) lubrication analysis for dynamically loaded journal bearings is presented. An algorithm for mass conserving cavitation is included, and the effect of viscosity variation with the temperature is taken into account. The Reynolds equation in the film is solved using the finite element (FE) discretization. Thermal distortions as well as the elastic deformation of the bearing surfaces are computed using the FE method. The temperature of the lubrication film is treated as a time-dependent three-dimensional variable with a parabolic variation with respect to the film thickness. In order to compute the temperature of the film and its surrounding solid surfaces, a new heat flux conservation algorithm is proposed. An important element in this analysis is the consideration of thermal boundary layers for solids. It is known that the thermal transients on the film-solid interfaces and the dynamic loading have the same period (one cycle). However, beyond the thermal boundary layers, the time scale for thermal transient in the journal and bushing are several orders of magnitude greater than those for the oil film. The Fourier series approximates the instantaneous temperature fields in the solid boundary layers. In this way, the mean heat flux that passes into the solid can be computed and a steady-state heat conduction equation can be used to obtain thermal fields inside the solids. Finally, solving the complex problem of big-end connecting-rod bearing TEHD lubrication proves the efficiency of the algorithm. Oil film temperatures are found to vary considerably over the time and space.

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Copyright © 2006 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

Boundary conditions for one film mesh element

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Figure 2

Film temperature variation in the middle bearing—Mitsui comparison

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Figure 3

Sinusoidal bearing loads at 6500rev∕min

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Figure 4

Schema of the solid interfaces

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Figure 5

Thermal field in the middle plane for 0deg rotational angle. Oil supply boundary conditions: (a) computed supply temperature with a parabolic variation, (b) computed supply temperature with a linear variation, (c) imposed supply temperature with a parabolic variation, (d) imposed supply temperature with a linear variation

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Figure 6

Thermal field in the middle plane for 0deg rotational angle. Edge bearing boundary conditions: (a) imposed temperature for the bearing edges and (b) computed temperature (average film) for the bearing edges

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Figure 7

Load diagram for a connecting rod bearing at 6500rev∕min

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Figure 8

Minimum film thickness, elastic deformation and thermal deformation, variation with the crank angle

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Figure 9

Thermal field in the middle plane for 0, 180, 360, and 540deg crank angles

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Figure 10

Thermal field on the solid surfaces

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Figure 11

Temperature variation in the film thermal boundary layer

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Figure 12

Orbit diagram and minimum film thickness variation for a con-rod big-end bearing: comparison between TEHD and EHD study

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