Micro-EHL in Lubricated Concentrated Contacts

Schipper, Dirk J.; Vroegop, P.H.; Gee, A.W.J. de; Bosma, R.H.

doi:10.1115/1.2920269

Cited by 19 publications

(4 citation statements)

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“…By including the increasing conformity of the two bodies the load carrying capacity of the system is increased due to running in under mild conditions as the temperature field is lowered. This effect is also observed in the study done by Schipper et al [17]. This effect will be discussed more intensively in the results section of this article.…”

Section: Theorysupporting

confidence: 78%

Transition from mild to severe wear including running in effects

Bosman

Schipper

2011

Wear

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Section: Theorysupporting

confidence: 78%

Transition from mild to severe wear including running in effects

Bosman

Schipper

2011

Wear

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“…7. The fluid film shear stress ô is expressed in terms of Newtonian and non-Newtonian behaviour and recognizes the existence of a limiting shear stress [30]. ó is the normal or Hertzian stress acting on the contact; hence, ô f = ó represents the traction coefficient.…”

Section: Contact Surface Shear Stressmentioning

confidence: 99%

Life ratings for ball and roller bearings

Harris

Barnsby

2001

Proceedings of the Institution of Mechanical Engineers, Part J:

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Since the beginning of the twentieth century, bearing manufacturers and users have sought to predict the fatigue endurance of ball and roller bearings. The first generally accepted method to predict bearing life and rate bearings accordingly was published in 1947 by Lundberg and Palmgren (LP). This method was adopted in the United States as the basis for a Standard in 1956, and it remains the basis for the current ISO Standard. The LP theory, however, pertains only to bearings manufactured from AISI 52100 through-hardened steel, and it permits ratings for bearings loaded solely by the Hertz stresses associated with simple applied loading. To accommodate the various steels from which bearings are manufactured and the effect of lubrication on fatigue life, the life calculated according to the LP method was adjusted by life modification factors; this multiplicative life factor concept was inserted into the ISO Standard during the 1970s. Even with these life factors, fatigue lives experienced in many bearing applications substantially exceeded the predictions. In 1985, Ioannides and Harris (IH) proposed a method based on the LP theory, but including a fatigue limit stress. Life predicted according to their method could ideally be infinite if the fatigue limit stress is not exceeded. Moreover, as opposed to the LP theory, which relies on Hertz stresses alone, the IH method permitted consideration of the totality of stresses acting on the rolling contact members. The IH method has now been further developed into an even more generalized Stress-Life method. This method, which is still based on the LP formulation, employs a single stress-life factor to modify the LP predicted fatigue life. In the fatigue life prediction for a bearing application, the stress-life factor integrates the effect on life of all applied, induced and material residual stresses together with empirically determined fatigue limit stresses. This paper details the historical development of bearing life ratings culminating in the detailed methods of application of the stress-life method.

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“…Schipper et al. 19 suggested that micro-EHL is possible with the boundary lubrication condition below a certain value of surface roughness. The occurrence of micro-EHL indicates the presence of a thin lubrication film between the interacting asperities.…”

Section: Resultsmentioning

confidence: 99%

Tribological behavior of polyacetal composite filled with rice bran ceramics particles under water lubrication

Shibata

Takeshi

Yamaguchi

et al. 2017

Journal of Composite Materials

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We investigated the tribological behavior of polyacetal polyoxymethylenecomposite filled with rice bran ceramics particles under water lubrication, compared to those of polyoxymethylene composites filled with glass beads and glass fibers. Furthermore, the local contact pressure between a particle and the paired ball was calculated based on a simple contact model. The polyoxymethylene/rice bran ceramics composite showed low wear (ws < 10−8 mm2/N) and low friction (μ < 0.10) under water lubrication, irrespective of the normal load and sliding velocity. On a Stribeck curve, the lubrication condition of the polyoxymethylene/rice bran ceramics composite appeared to be near hydrodynamic lubrication. The specific wear rates of the polyoxymethylene/rice bran ceramics composite were the lowest of the composites, regardless of the bearing characteristic number. A smooth worn surface was observed for both the polyoxymethylene/rice bran ceramics composite and the paired ball. The dimensionless roughness parameters of the polyoxymethylene/rice bran ceramics composite were smaller than 1.0, irrespective of the bearing characteristic number. The friction coefficients of the polyoxymethylene composites decreased exponentially with decreasing dimensionless roughness parameter; the low friction of the polyoxymethylene/rice bran ceramics composite resulted from the small roughness parameters. The rice bran ceramics particles indicated a small contact pressure per particle, which was nearly half the Vickers hardness of the steel ball. As a result, the rice bran ceramics particles rarely damaged the steel ball with increasing surface roughness. Therefore, the low friction of the polyoxymethylene composite filled with the rice bran ceramics particles was attributable to the decrease in the roughness, e.g., polishing without the formation of a transfer film and the filler detachment.

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Micro-EHL in Lubricated Concentrated Contacts

Cited by 19 publications

References 0 publications

Transition from mild to severe wear including running in effects

Transition from mild to severe wear including running in effects

Life ratings for ball and roller bearings

Tribological behavior of polyacetal composite filled with rice bran ceramics particles under water lubrication

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