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Effect of starvation on film thickness and traction under elastohydrodynamic rolling and sliding conditionsTraction measurements under starved elastohydrodynamic conditions were obtained for a point-contact geometry. Simultaneous measurements of the film thickness and the location of the inlet lubricant boundary were made. Optical interferometry was used to measure film thickness. The thickness of a starved film for combined rolling and sliding conditions varies with the location of the inlet boundary in the same way as previously found for pure rolling conditions. When the fluid velocity distribution is calculated in the inlet region by a Reynolds lubrication analysis, backflow is seen to occur over a portion of the inlet region. Backflow is essential for the establishment of a flooded condition. The location of certain fluid velocity conditions within the inlet region, as suggested in the literature, does not adequately describe the onset of starvation. For the same slide-roll ratio a starved film was observed to possess greater traction than a flooded film. Traction measurements under starved conditions were also compared with those under flooded conditions for equivalent shear rates in the Hertzian region. When the shear rates within the Hertzian region were low and the film was severely starved, the measured tractions were lower than expected. This may be due to large shear stresses developed by the large pressure gradients that are generated in the inlet region when it is severely starved.
Document ID
19760003387
Acquisition Source
Legacy CDMS
Document Type
Other - NASA Technical Note (TN)
Authors
Wedeven, L. D.
(NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
September 3, 2013
Publication Date
October 1, 1975
Subject Category
Mechanical Engineering
Report/Patent Number
E-8412
NASA-TN-D-8087
Accession Number
76N10475
Funding Number(s)
PROJECT: RTOP 505-04
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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