scholarly journals Closure to “Discussion of ‘Thermal Analysis of Elastohydrodynamic Lubrication of Line Contacts Using the Ree-Eyring Fluid Model’” (1991, ASME J. Tribol., 113, pp. 242–243)

1991 ◽  
Vol 113 (2) ◽  
pp. 243-244
Author(s):  
Shao Wang ◽  
C. Cusano ◽  
T. F. Conry
Keyword(s):  
Thermal Analysis ◽  
Fluid Model ◽  
Elastohydrodynamic Lubrication ◽  
Line Contacts

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 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.

Couette Dominance Used for Non-Newtonian Elastohydrodynamic Lubrication

1994 ◽  
Vol 116 (1) ◽  
pp. 47-55 ◽  
Author(s):  
C. M. Myllerup ◽  
A. A. Elsharkawy ◽  
B. J. Hamrock
Keyword(s):  
Newtonian Fluid ◽  
Fluid Model ◽  
Elastohydrodynamic Lubrication ◽  
Shear Strain Rate ◽  
High Shear Stress ◽  
Line Contacts ◽  
Stress Boundary Conditions ◽  
Stress Boundary ◽  
Good Agreement ◽  
Low Shear

The perturbational approach that assumes Couette dominance in non-Newtonian elastohydrodynamic lubrication analysis is discussed. The assumption is found valid for non-Newtonian fluid models exhibiting Newtonian properties at low shear strain rate. A general non-Newtonian fluid model which meets that requirement is incorporated into elastohydrodynamic lubrication analysis of line contacts by using the perturbational approach. In the case of a circular fluid model the results obtained from the perturbational approach are in good agreement with those obtained from the direct approach. However, a better convergence and the possibility of avoiding using stress boundary conditions at high shear stress can be achieved by using the perturbational approach. Results are presented for various values of the shape exponent in the general model, and it transpires that this also is an important parameter of the fluid model.

Combined Effects of Shear Thinning and Viscous Heating on EHL Characteristics of Rolling/Sliding Line Contacts

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Punit Kumar ◽  
M. M. Khonsari
Keyword(s):  
Film Thickness ◽  
Thermal Effect ◽  
Fluid Model ◽  
Elastohydrodynamic Lubrication ◽  
Shear Thinning ◽  
Viscous Heating ◽  
Shear Thinning Fluids ◽  
Line Contacts ◽  
Power Law Index ◽  
Good Agreement

The combined influence of shear thinning and viscous heating on the behavior of film thickness and friction in elastohydrodynamic lubrication (EHL) rolling/sliding line contacts is investigated numerically. The constitutive equation put forward by Carreau is incorporated into the model to describe shear thinning. An extensive set of numerical simulations is presented. Comparison of the film thickness predictions with published experiments reveals good agreement, and it is shown that thermal effect plays an important role in the precise estimation of EHL film thickness and friction coefficient. Parametric simulations show that thermal effect in shear-thinning fluids is strongly affected by the power-law index used in the Carreau equation. Comparisons of prediction of the Newtonian fluid model are presented to quantify the degree to which it overestimates the film thickness.

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.

Simulation of Plasto-Elastohydrodynamic Lubrication in Line Contacts of Infinite and Finite Length

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Tao He ◽  
Jiaxu Wang ◽  
Zhanjiang Wang ◽  
Dong Zhu
Keyword(s):  
Surface Roughness ◽  
Finite Length ◽  
3D Model ◽  
Three Dimensional ◽  
Elastohydrodynamic Lubrication ◽  
Axial Direction ◽  
Contact Length ◽  
Line Contact ◽  
Line Contacts ◽  
3D Surface Topography

Line contact is common in many machine components, such as various gears, roller and needle bearings, and cams and followers. Traditionally, line contact is modeled as a two-dimensional (2D) problem when the surfaces are assumed to be smooth or treated stochastically. In reality, however, surface roughness is usually three-dimensional (3D) in nature, so that a 3D model is needed when analyzing contact and lubrication deterministically. Moreover, contact length is often finite, and realistic geometry may possibly include a crowning in the axial direction and round corners or chamfers at two ends. In the present study, plasto-elastohydrodynamic lubrication (PEHL) simulations for line contacts of both infinite and finite length have been conducted, taking into account the effects of surface roughness and possible plastic deformation, with a 3D model that is needed when taking into account the realistic contact geometry and the 3D surface topography. With this newly developed PEHL model, numerical cases are analyzed in order to reveal the PEHL characteristics in different types of line contact.

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