D. M. Sanborn

Infrared Temperature Mapping in Elastohydrodynamic Lubrication

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.

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

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...

Temperature Measurements in Sliding Elastohydrodynamic Point Contacts

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.

Direct surface temperature measurement by infrared radiation in elastohydrodynamic contacts and the correlation with the blok flash temperature theory

Abstract An infrared microdetector was employed to measure surface temperatures in elastohydrodynamic contacts with Hertz pressures up to 2 GPa, sliding velocities up to 6.0 m s−1 and rolling velocities up to 1.25 m s−1 with slide/roll ratios from −2 to +2. Different surface roughnesses were also employed. The lambda ratio (mean film thickness to composite surface roughness) was varied from 20 to considerably less than 1. The surfaces employed were AISI 52100 steel against Al2O3 and the lubricant was a typical naphthenic hydrocarbon. High maximum surface temperatures have been observed (to 300 °C). Analysis of the data shows very good correlation with the Blok flash temperature theory for simple sliding (∑ = ± 2). An extension of this theory to include two moving surfaces at unequal temperatures predicts the ball surface temperature quite accurately.

Effects of Load, Speed, and Surface Roughness on Sliding EHD Contact Temperatures

An infrared technique has been used to determine the effects of load, speed and surface roughness on temperature in a sliding elastohydrodynamic (EHD) point contact. Ball surface temperatures are reported for sliding speeds of 0.35 to 5.08 m/s at 0.52 to 2.03 GN/per sq m maximum pressure with surface roughness in the range 0.01 to 0.38 micron c.l.a. The relationship between asperity interaction, as measured by relocation surface profilimetry and high frequency temperature measurements, and the ratio of film thickness to surface roughness has also been studied.

Surface Temperature Measurements in Rolling and Sliding EHD Contacts

A number of devices in which concentrated contact conditions occur have relatively small amounts of slip or none at all. A knowledge of contact temperatures developed under these conditions is essential to understanding the lubricant rheology and also the fluid film failure. In this study, moving surface temperature measurements in rolling and sliding EHD point contacts were made using an available infrared technique. Film thickness and traction have also been measured. Slide-to-roll ratios of −2 to +2 have been studied. By using a different kinematic configuration, stationary surface temperatures have also been measured. It has been shown that, while surface temperature rises in the low slip region are relatively small, stationary surface temperatures are significantly higher than the moving surface temperatures. Flash temperature theory has been extended to cover the combined rolling and sliding conditions. Correlation between the predicted and the measured values has also been performed. Presented at t...

Asperity interactions in EHD contacts

Infrared temperature measurements, ferrographic analysis, and surface profilimetry were used to monitor asperity interactions in a sliding EHD point contact. The contact temperature and surface profile signals obtained both before and after a run-in period are compared in the frequency domain by means of a Fourier analyzer. The interaction of surface asperities is accompanied by the presence of a high frequency component in the infrared signal. It is also shown that only a relatively narrow band of wavelengths of the surface profile spectrum are relevant in the interaction process.

Dynamics of roller bearings considering elastohydrodynamic forces

The life and load carrying capacity of roller bearings are highly influenced by the sliding velocities at the contacts between rollers and races. In this investigation, a computational model was developed to predict traction forces, forces on the cage, sliding and spinning speeds of the roller when the bearing is lubricated with a fluid of known traction coefficient characteristics as functions of pressure and velocities. Presented at the JSLE/ASLE International Lubrication Conference in Tokyo, Japan, June 9–11, 1975.