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The Stribeck curve is an overall view of friction variation in the entire range of lubrication, including the hydrodynamic, mixed, and boundary lubrication. This paper presents the results of research on the friction of a journal-bearing conformal contact system in the form of Stribeck curves through numerical simulation. The surface roughness of the journal and the bearing and material elasticity and thermoelasticity are included in the modeling, and their influences on the results of Stribeck curves are discussed. A three-dimensional Stribeck surface is constructed to illustrate the load effect on friction for the modeled journal-bearing structure.
KEY WORDS
Stribeck Curve; Conformal Contact; Journal Bearing
(ProQuest-CSA LLC: ... denotes formulae omitted.)
INTRODUCTION
Most heavy-duty elements operate in a wide range of lubrication regimes, including full-film, mixed, and boundary lubrication. The Stribeck curve is an overall view of friction variation in the entire range of lubrication. The concept of systematically describing friction variation in lubrication was due to the German Professor, Richard Stribeck, who in 1902 confirmed the existence of a minimum friction through his extensive journal-bearing friction experiments. Ludwig Gumbel later in 1914 summarized the Stribeck results into a single curve by means of dimensionless parameters. Mayo Hersey (1) showed that friction due to viscous shear was a unique function of the product of viscosity (ç) by rotational speed (N) divided by the average load (P), which is called the Hersey number. Such a plot with friction coefficient plotted against the Hersey number is now commonly known as the Stribeck curve. Professor Dowson (2) summarized in his book the history of the development of the Stribeck curve concept.
The understanding and utilization of Stribeck curves have advanced from friction expressions to the division of lubrication regimes (Luengo, et al. (3)). Reddy, et al. (4) presented a Stribeck diagram of friction for a tilting pad journal bearing. Recently, Xiao, et al. (5) studied the friction behavior of a rolling contact in terms of Stribeck curves. Figure 1 schematically illustrates the concept of the Stribeck curve cited from Williams (6), in which the friction coefficient is expressed as a function of the Hersey number (nN/P). The diagram shows the existence of the minimum friction coefficient, regimes of lubrication, and the trend of friction variation. It seems that...