Thermal Elastohydrodynamic Lubrication of Rough Surfaces

1990 ◽  
Vol 112 (2) ◽  
pp. 341-346 ◽  
Author(s):  
F. Sadeghi ◽  
Ping C. Sui
Keyword(s):  
Energy Equation ◽  
Control Volume ◽  
Rough Surfaces ◽  
Elastohydrodynamic Lubrication ◽  
Radius Of Curvature ◽  
Transient Effects ◽  
Heavy Load ◽  
Elasticity Equations ◽  
Ehd Lubrication ◽  
Control Volume Finite Element

A numerical solution to the problem of thermal and compressible elastohydrodynamic (EHD) lubrication of rolling/sliding rough surfaces was obtained by neglecting the transient effects. The technique involves the simultaneous solution of thermal Reynolds and modified elasticity equations using the Newton-Raphson technique, and the energy equation using the control volume finite element method. The effects of various loads, amplitude of asperity, and radius of curvature of asperity have been investigated. Results have been presented for moderate dimensionless load of W = 9.03 × 10−5 to heavy load of W = 2.3 × 10−4 at the speed of U* = 9.2 × 10−11. The results indicate that surface roughness significantly affect the pressure, temperature, and traction in EHD lubrication.

Thermal Elastohydrodynamic Lubrication of Rolling/Sliding Contacts

1990 ◽  
Vol 112 (2) ◽  
pp. 189-195 ◽  
Author(s):  
F. Sadeghi ◽  
P. C. Sui
Keyword(s):  
Finite Element ◽  
Temperature Effects ◽  
Energy Equation ◽  
Control Volume ◽  
Elastohydrodynamic Lubrication ◽  
Sliding Contacts ◽  
Simultaneous System ◽  
Elasticity Equations ◽  
Newton Raphson ◽  
Control Volume Finite Element

A complete numerical solution of thermal compressible elastohydrodynamic lubrication of rolling/sliding contacts has been obtained. The Newton-Raphson technique is used to solve the simultaneous system of Reynolds and elasticity equations. The control volume finite element modeling was employed to solve the energy equation and its boundary conditions. The effects of various loads, speeds, and slip conditions on the lubricant temperature, film thickness, and friction force have been investigated. The results indicate that the temperature effects are significant and cannot be neglected.

Time Dependent Line EHD Lubrication Using the Multigrid/Multilevel Technique

1992 ◽  
Vol 114 (1) ◽  
pp. 68-74 ◽  
Author(s):  
K. F. Osborn ◽  
F. Sadeghi
Keyword(s):  
Elastohydrodynamic Lubrication ◽  
Time Dependent ◽  
Operating Parameters ◽  
Response Behavior ◽  
Steady State Condition ◽  
Elasticity Equations ◽  
Ehd Lubrication ◽  
Line Contacts ◽  
Lubricated Contact ◽  
Analysis Models

A numerical solution of time dependent compressible elastohydrodynamic lubrication of line contacts has been obtained. The results show the effects of various operating parameters on the transient response behavior of a lubricated contact. The analysis models a startup situation where the surfaces are initially at rest and in contact. Then, with the contacts operating at a given load and speed, the analysis is run until the pressure and film thickness reach a steady-state condition. A multigrid/multilevel technique is used to simultaneously solve the time dependent Reynolds and elasticity equations. The effects of various loads and speeds have been investigated. Results are presented for nondimensional loads ranging from W = 2.0 × 10−5 to W = 2.3 × 10−4 and nondimensional speeds ranging from U = 1.0 × 10−12 to U = 1.0 × 10−10.

Compressible Elastohydrodynamic Lubrication of Rough Surfaces

1989 ◽  
Vol 111 (1) ◽  
pp. 56-62 ◽  
Author(s):  
F. Sadeghi ◽  
Ping C. Sui
Keyword(s):  
Numerical Solution ◽  
Rough Surfaces ◽  
Roughness Parameter ◽  
Elastohydrodynamic Lubrication ◽  
Surface Pattern ◽  
Simultaneous System ◽  
Elasticity Equations ◽  
Newton Raphson ◽  
Compression Effects

A complete numerical solution of compressible elastohydrodynamic lubrication of rough surfaces has been obtained. The Newton-Raphson technique is used to solve the simultaneous system of modified compressible Reynolds and elasticity equations. The effects of various loads, surface pattern, and roughness parameter have been investigated. Results have been presented for loads ranging from W = 2.0452 × 10−5 to W = 2.3 × 10−4 at the speed of U = 1.0 × 10−11. The results indicate that the compression effects are significant and cannot be neglected.

Theoretical analysis of a rolling-sliding elastohydrodynamic lubrication line contact with a subsurface inclusion

2019 ◽  
Vol 233 (8) ◽  
pp. 1197-1207
Author(s):  
Armando Félix Quiñonez ◽  
Guillermo E Morales Espejel
Keyword(s):  
Elastohydrodynamic Lubrication ◽  
Element Model ◽  
Von Mises Stress ◽  
Transient Effects ◽  
Mean Velocity ◽  
The Matrix ◽  
Soft Inclusion ◽  
The Mean ◽  
Von Mises ◽  
Fully Coupled

This work investigates the transient effects of a single subsurface inclusion over the pressure, film thickness, and von Mises stress in a line elastohydrodynamic lubrication contact. Results are obtained with a fully-coupled finite element model for either a stiff or a soft inclusion moving at the speed of the surface. Two cases analyzed consider the inclusion moving either at the same speed as the mean velocity of the lubricant or moving slower. Two additional cases investigate reducing either the size of the inclusion or its stiffness differential with respect to the matrix. It is shown that the well-known two-wave elastohydrodynamic lubrication mechanism induced by surface features is also applicable to the inclusions. Also, that the effects of the inclusion become weaker both when its size is reduced and when its stiffness approaches that of the matrix. A direct comparison with predictions by the semi-analytical model of Morales-Espejel et al. ( Proc IMechE, Part J: J Engineering Tribology 2017; 231) shows reasonable qualitative agreement. Quantitatively some differences are observed which, after accounting for the semi-analytical model's simplicity, physical agreement, and computational efficiency, may then be considered as reasonable for engineering applications.

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.

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