Thermal Analysis of Elastohydrodynamic Lubrication of Line Contacts Using the Ree-Eyring Fluid Model

1991 ◽  
Vol 113 (2) ◽  
pp. 232-242 ◽  
Author(s):  
Shao Wang ◽  
C. Cusano ◽  
T. F. Conry
Keyword(s):  
Thermal Conductivity ◽  
Thermal Analysis ◽  
Control Volume ◽  
Fluid Model ◽  
Elastohydrodynamic Lubrication ◽  
Reduction Factor ◽  
Line Contacts ◽  
Eyring Equation ◽  
Maximum Temperatures ◽  
Control Volume Approach

A thermal Reynolds-Eyring equation is derived for elastohydrodynamic lubrication of line contacts. A control volume approach is used to analyze the inlet region where back-flow occurs. Numerical results are obtained and used to develop a formula for the thermal and non-Newtonian (Ree-Eyring) film thickness reduction factor. Results for maximum temperatures and traction coefficients are also presented. The pressure dependence of lubricant thermal conductivity is found to significantly affect the maximum lubricant temperature.

A Complete Solution for Thermal-Elastohydrodynamic Lubrication of Line Contacts Using Circular Non-Newtonian Fluid Model

1992 ◽  
Vol 114 (3) ◽  
pp. 540-551 ◽  
Author(s):  
Hsing-Sen S. Hsiao ◽  
Bernard J. Hamrock
Keyword(s):  
Boundary Conditions ◽  
Newtonian Fluid ◽  
Energy Equation ◽  
Control Volume ◽  
Fluid Model ◽  
Complete Solution ◽  
Circular Model ◽  
Line Contacts ◽  
Stress Boundary Conditions ◽  
Stress Boundary

A complete solution is obtained for elastohydrodynamically lubricated conjunctions in line contacts considering the effects of temperature and the non-Newtonian characteristics of lubricants with limiting shear strength. The complete fast approach is used to solve the thermal Reynolds equation by using the complete circular non-Newtonian fluid model and considering both velocity and stress boundary conditions. The reason and the occasion to incorporate stress boundary conditions for the circular model are discussed. A conservative form of the energy equation is developed by using the finite control volume approach. Analytical solutions for solid surface temperatures that consider two-dimensional heat flow within the solids are used. A straightforward finite difference method, successive over-relaxation by lines, is employed to solve the energy equation. Results of thermal effects on film shape, pressure profile, streamlines, and friction coefficient are presented.

Thermal Non-Newtonian Elastohydrodynamic Lubrication of Line Contacts Under Simple Sliding Conditions

1992 ◽  
Vol 114 (2) ◽  
pp. 317-327 ◽  
Author(s):  
Shao Wang ◽  
T. F. Conry ◽  
C. Cusano
Keyword(s):  
Film Thickness ◽  
Surface Temperature ◽  
Thermal Effects ◽  
Elastohydrodynamic Lubrication ◽  
Reduction Factor ◽  
Simple Formulation ◽  
Maximum Surface ◽  
Line Contacts ◽  
Traction Coefficient ◽  
Maximum Surface Temperature

A computationally simple formulation for the stationary surface temperature is developed to examine the thermal non-Newtonian EHD problem for line contacts under simple sliding conditions. Numerical results obtained are used to develop a formula for a thermal and non-Newtonian (Ree-Eyring) film thickness reduction factor. Results for the maximum surface temperature and traction coefficient are also presented. The thermal effects on film thickness and traction are found to be more pronounced for simple sliding than for combined sliding and rolling conditions.

Elastohydrodynamic Lubrication Between Rolling and Sliding Ceramic Cylinders: An Experimental Investigation1

2000 ◽  
Vol 122 (4) ◽  
pp. 721-724 ◽  
Author(s):  
T. Sperrfechter ◽  
R. Haller
Keyword(s):  
Thermal Conductivity ◽  
Film Thickness ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Elastohydrodynamic Lubrication ◽  
Ceramic Materials ◽  
Oil Film ◽  
Thin Film Sensors ◽  
Line Contacts ◽  
Clear Increase

The present work focuses on the investigation of the influence of bulk ceramic materials on the behavior of elastohydrodynamically (EHD) lubricated line contacts. The materials alumina Al2O3, zirconium oxide ZrO2 and aluminum nitride (AIN) are used. Comparative measurements were taken with steel disks made of 42CrMo4. Of primary importance are the material parameters Young’s modulus and thermal conductivity. The experimental variables pressure, temperature and oil film thickness in the EHD contact of a two disk test rig were measured with the aid of evaporated thin film sensors. As the results show, an increase in the Young’s modulus causes a clear increase of the pressure level. The oil film thickness distributions show a decline of the flattening width and of the constriction occurring at the contact outlet. The influence of the material with respect to its thermal conductivity dominates, above all, in the region of the load transmitting contact zone. The transition from a good to a bad conductor of heat causes a rise in temperature, more prominent for materials with lower thermal conductivities. This leads to viscosity decrease causing clearly reduced oil film thicknesses in the contact. [S0742-4787(00)01404-1]

A Circular Non-Newtonian Fluid Model: Part II—Used in Microelastohydrodynamic Lubrication

1990 ◽  
Vol 112 (3) ◽  
pp. 497-505 ◽  
Author(s):  
Rong-Tsong Lee ◽  
B. J. Hamrock
Keyword(s):  
Newtonian Fluid ◽  
Fluid Model ◽  
Elastohydrodynamic Lubrication ◽  
Hertzian Contact ◽  
Surface Irregularity ◽  
Good Prediction ◽  
Moving Surface ◽  
Stationary Surface ◽  
Lubrication Performance ◽  
Line Contacts

A circular non-Newtonian fluid model and system approach is used in this paper to study the effect of a stationary surface irregularity where the film shape has been modified in the conjunctions of line contacts. A modified transient Reynolds equation is developed in this paper and is used to study the effect of a moving surface irregularity in the problem of microelastohydrodynamic lubrication. Lubrication performance factors such as pressure and film profiles were studied for both a stationary and a moving surface irregularity in a lubricated conjunction. The shear stress and traction coefficient for various height of the surface irregularity were also studied for a stationary surface irregularity. Results show that the film shape obtained from full-film elastohydrodynamic lubrication theory still gave a good prediction except when the surface irregularity occurred at inlet (Xp = − 1.0), but it failed to explain the high pressure and film fluctuations around the surface irregularity which was in the Hertzian contact zone. A bump or a groove occurring in the outlet around (Xp = 1.0) significantly affected the location of the outlet boundary, and the depth of the nip film thickness in the outlet caused by the surface irregularity profoundly affected the pressure spike for both a stationary and a moving surface irregularity.

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