Fluid Rheological Effects in Sliding Elastohydrodynamic Point Contacts With Transient Loading: 1—Film Thickness

Sanborn, D. M.; Winer, W. O.

doi:10.1115/1.3451560

Cited by 47 publications

(18 citation statements)

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“…Temperature rise due to single heat source (°C) A Area of element in thermal analysis (m 2 ) C Jaeger heat transfer coefficient (km 2 The temperature rise caused by fluid shear from sliding (case i) has been studied extensively, e.g. [2][3][4][5], whereas less attention has been paid to cases (ii) and (iii), which can occur under pure rolling conditions.…”

Section: List Of Symbols Amentioning

confidence: 99%

Compression Heating and Cooling in Elastohydrodynamic Contacts

2009

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In this study, the infrared temperature mapping technique, originally developed by Sanborn and Winer (Trans ASME J Tribol 93: [262][263][264][265][266][267][268][269][270][271] 1971) and extended by Spikes et al. (Tribol Lett 17(3):593-605, 2004), has been made more sensitive and used to study the temperature rise of elastohydrodynamic contacts in pure rolling. Under such conditions lubricant shear heating within the contact is considered negligible and this allows temperature changes due to lubricant compression to be investigated. Pure rolling surface temperature distributions have been obtained for contacts lubricated with a range of lubricants, included a group I, and group II mineral oil, a polyalphaolefin (group IV), the traction fluid Santotrac 50 and 5P4E, a five-ring polyphenyl-ether. Resulting maps show the temperature rise in the contact increases in the inlet due to compression heating and then decreases and in most cases becomes negative in the exit region due to the effect of decompression. Temperature changes increase with entrainment speed but in the current tests are always very small, and less than 1°C. Contact temperature rises from compression were compared to those from sliding contacts (where a slide-roll ratio of 0.5 was applied). Here the contribution to the contact temperature from compression is shown to decrease dramatically with entrainment speed. The lubricant 5P4E is found to behave differently from other lubricants tested in that it showed a peak in temperature at the outlet. This effect becomes more pronounced with increasing speed, and has tentatively been attributed to a phase change in the exit region. Using moving heat source theory, the measured temperature distributions have been converted to maps showing rate of heat input into each surface and the latter compared with theory. Qualitative agreement between theory and experiment is found, and a more accurate theoretical comparison is the subject of ongoing study.

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Section: List Of Symbols Amentioning

confidence: 99%

Compression Heating and Cooling in Elastohydrodynamic Contacts

2009

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“…As a result, the nonNewtonian characteristics of lubricants have become important. Sanborn and Winer [1] reported experimental confirmation of the essential features. They found that a dimple forms at the center of contact.…”

Section: Introductionmentioning

confidence: 85%

Elastohydrodynamic Lubrication of Circular Contacts at Impact Loading with Generalized Newtonian Lubricants

et al. 2007

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In this article, pure squeeze elastohydrodynamic lubrication (EHL) motion of circular contacts with power law model lubricant is explored at impact loading. The coupled transient modified Reynolds, the elasticity deformation, and the ball motion equations are solved simultaneously, thus obtaining the transient pressure profiles, film shapes, normal squeeze velocities, and accelerations. The simulation results reveal that the greater the flow index (n), the earlier the pressure spike and the dimple form, while the maximum pressure and the film thickness increase, and the diameter of the dimple, the maximum value of the impact force, the rebounding velocity, and the acceleration decrease. Further, this analysis numerically demonstrates that the contact central pressure for a ball impacting and rebounding from a lubricated surface reached two peaks during the total impact period. As the flow index increases, the primary and the secondary peak increase, and the first and second peaks form earlier; as the total impact time decreases. Moreover, the phase shift between the time of the peak value of the squeeze acceleration and the zero value of the squeeze velocity increase with increasing flow index.

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“…The experimental data of [20,21] also show a film thickness sensitivity to stress greater than theoretical for maximum Hertz stresses 9 2 greater than about 1.04x10 N/m (150,000 psi). These data, obtained by an optical interferometry technique with sliding point contacts tend to confirm the measurements obtained by the X-ray technique of [10,11].…”

Section: Introductionmentioning

confidence: 97%

“…There has been, however, increasingly more attention directed at obtaining these pressure-viscosity data in recent years [21,26,28,29].…”

Section: Effect Of Lubricant On Film Thickness Correlationmentioning

confidence: 99%