The methods of measuring the rheological properties of EHD lubricants are reviewed, but for pressures in excess of 1.0 GPa there is currently no simple alternative to the disc machine. A technique has been developed which enables disc machine traction tests to be carried out at constant mean film temperature. Isothermal tests provide further evidence for the existence of a limiting shear stress τc at which the fluid shears in the manner of a plastic solid. At stresses below this limit the experimental data are found to be in very good accord with the non-linear Maxwell rheological model based on the Eyring theory of fluid flow proposed by Johnson and Tevaarwerk and by Hirst and Moore. The model incorporates three fluid properties: shear modulus G, viscosity τ and Eyring stress τ0. Disc machine measurements of τ, τ0 and the limiting shear stress τc for three fluids—a mineral oil HVI 650, a synthetic polyphenyl ether 5P4E and a traction fluid Santotrac 50—are presented for a range of pressures (0.6–2.5 GPa)...

The Rheological Properties of Elastohydrodynamic Lubricants

https://deepblue.lib.umich.edu/bitstream/handle/2027.42/24617/0000027.pdf?sequence=1&isAllowed=y

A review of scuffing and running-in of lubricated surfaces, with asperities and oxides in perspective

A review of the experimental techniques for the measurement of heat and temperatures generated in some manufacturing processes and tribology

Elastohydrodynamic and micro-elastohydrodynamic lubrication

New numerical results, based upon the concept of solidification, are produced which match the intriguing dimple observed by Kaneta in elastohydrodynamic lubrication of point contacts under pure sli...

On lubricant transport conditions in elastohydrodynamic conjuctions

A preliminary investigation into the possible role of glass transition and glassy state behavior of lubricants in EHD contacts is reported. Measurements of the glass transition of lubricants as a function of pressure by two methods are presented along with a discussion indicating possible implications of the results to EHD lubrication.

Glass Transitions in Lubricants: Its Relation to Elastohydrodynamic Lubrication (EHD)

An improved technique for the measurement of temperature distributions in an EHD conjunction is presented. The technique reported here employs the infrared radiation emitted by the EHD conjunction and appears more rigorous, more reliable, and less cumbersome than that reported previously by the authors. Detailed mapping of fluid temperature (averaged through the thickness) and the ball surface temperature can be obtained. These temperature distributions have been reported for a naphthenic mineral oil for peak Hertz pressures of 1.05 and 1.51 GN/sq m (148 and 219 kpsi), at sliding speeds ranging from 0.35 to 12.7 m/s (13.4 to 500 ips) and a bath temperature of 40 C.

Infrared Temperature Mapping in Elastohydrodynamic Lubrication

A capillary viscometer was used to measure viscosity as a function of pressure, temperature, and shear stress for a number of lubricants. Measurements were made at 38 C, 99 C, and 149 C (100 F, 210 F, and 300 F), gauge pressure to 5.5 × 108 N/m2 (8 × 104 psi), and shear stresses to 106 N/m2 (14.5 psi). At 38 C (100 F), the order of the pressure-viscosity coefficients for the unformulated fluids was: fluorinated polyether > synthetic hydrocarbon > naphthenic mineral oil > synthetic paraffinic oil (lot 4) > C-ether ≅ synthetic paraffinic oil (lot 3) > polyalkyl aromatic > advanced ester. All pressure viscosity coefficients decreased with increasing temperature. Fair agreement was obtained when pressure-viscosity coefficients at 38 C (100 F) and 6.9 × 107 N/m2 (104 psi) were compared to data from other investigators using different techniques (optical elastohydrodynamics, oscillating crystal, and low shear capillary viscometry). Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME...

Pressure-viscosity measurements for several lubricants to 550 meganewtons per square meter /80,000 PSI/ and 149 C /300 F/

Techniques using the infrared radiation emitted by a sliding elastohydrodynamic (EHD) point contact to measure oil film and surface temperature are discussed. Temperature distributions in the EHD contact are presented for a naphthenic mineral oil at 1.04 GN/sq m (150,000 psi) Hertz pressure and several sliding velocities. Film temperatures as high as 360 C are reported at locations near the points of minimum film thickness in the contact side lobes.

D. M. Sanborn

Papers

Glass Transitions in Lubricants: Its Relation to Elastohydrodynamic Lubrication (EHD)

Infrared Temperature Mapping in Elastohydrodynamic Lubrication

Pressure-viscosity measurements for several lubricants to 550 meganewtons per square meter /80,000 PSI/ and 149 C /300 F/

Temperature Measurements in Sliding Elastohydrodynamic Point Contacts

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