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.

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.

Solving the Incompressible and Isothermal Problem in Elastohydrodynamic Lubrication Through an Integral Equation

1968 ◽  
Vol 90 (1) ◽  
pp. 262-270 ◽  
Author(s):  
K. Herrebrugh
Keyword(s):  
Integral Equation ◽  
Film Thickness ◽  
Numerical Solution ◽  
Analytic Functions ◽  
Large Range ◽  
Nonlinear Function ◽  
Elastohydrodynamic Lubrication ◽  
Elasticity Equations ◽  
Single Integral ◽  
Constant Viscosity

It will be shown that the hydrodynamic and elasticity equations in elastohydrodynamic lubrication can be coupled to one single integral equation of the following form: H(x)=f(x)−T∫abK(x,ξ)F{H(ξ)}dξ in which f(x) and K(x, ξ) are both known analytic functions inside [a, b], and F(H) is in general a nonlinear function of the dimensionless film thickness. A numerical solution of this integral equation for constant viscosity is presented for a large range of loading conditions.

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.

Non-Newtonian Elastohydrodynamic Lubrication of Point Contact

1991 ◽  
Vol 113 (4) ◽  
pp. 703-711 ◽  
Author(s):  
Kyung Hoon Kim ◽  
Farshid Sadeghi
Keyword(s):  
Film Thickness ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Two Dimensional ◽  
Point Contacts ◽  
Dimensionless Velocity ◽  
Simultaneous System ◽  
Elasticity Equations ◽  
Minimum Film Thickness ◽  
Pressure Spike

A numerical solution to the problem of isothermal non-Newtonian elastohydrodynamic lubrication of rolling/sliding point contacts has been obtained. The multigrid technique is used to solve the simultaneous system of two-dimensional modified Reynolds and elasticity equations. The effects of various loads, speeds, and slide to roll ratios on the pressure distribution, film thickness, and friction force have been investigated. Results for the dimensionless load W = 4.6 × 10−6 and 1.1 × 10−6, and the dimensionless velocity U = 3 × 10−10 and 3 × 10−11 are presented. The results indicate that slide to roll ratio has negligible effect on the minimum film thickness, however, it significantly reduces the pressure spike.

Thermal Elastohydrodynamic Lubrication of Rolling/Sliding Line Contacts

1992 ◽  
Vol 114 (4) ◽  
pp. 706-713 ◽  
Author(s):  
R. Wolff ◽  
T. Nonaka ◽  
A. Kubo ◽  
K. Matsuo
Keyword(s):  
Variable Viscosity ◽  
Elastohydrodynamic Lubrication ◽  
Longitudinal Direction ◽  
Rolling Velocity ◽  
Oil Film ◽  
Simultaneous System ◽  
Elasticity Equations ◽  
Line Contacts ◽  
Influence Of Temperature On ◽  
Constant Viscosity

The solution of thermal elastohydrodynamic lubrication of rolling/sliding line contacts has been obtained. The Newton-Raphson technique was used to solve the simultaneous system of Reynolds and elasticity equations. The energy equation with boundary conditions was solved by the finite-difference method. Two models were developed: one with a constant viscosity across the oil film and another with a variable viscosity across the oil film. Different viscosity formulas such as modified WLF, Roelands, and Barus can be used in these models. Viscosity measurements were also performed over wide ranges of pressure and temperature. A very good fitting of experimentally measured viscosity by modified WLF formula was obtained. The oil film shape and minimum film thickness were calculated for pure rolling and high slip. For high slip and high rolling velocity, a tapered wedge shape of EHL film (in the longitudinal direction) was obtained. These results show a good correlation with measurements reported in other papers. They show that there is a significant influence of temperature on the oil film shape.

Effect of Surface Roughness on the Point Contact EHL

1988 ◽  
Vol 110 (1) ◽  
pp. 32-37 ◽  
Author(s):  
D. Zhu ◽  
H. S. Cheng
Keyword(s):  
Reynolds Equation ◽  
Point Contact ◽  
Roughness Parameter ◽  
Elastohydrodynamic Lubrication ◽  
Surface Pattern ◽  
Roughness Parameters ◽  
Elasticity Equation ◽  
Asperity Contacts ◽  
Surface Irregularities ◽  
Effect Of Surface

In this paper a full numerical solution for the partial elastohydrodynamic lubrication in elliptical contacts is presented, and the procedure of computation is briefly described. The average Reynolds equation developed by Patir and Cheng, the elasticity equation, and the pressure-viscosity relationship are solved simultaneously. The asperity contacts are also taken into account by using the model contributed by Greenwood and Tripp. The distribution of surface irregularities is assumed to be Gaussian. The effects of various roughness parameters on the film thickness are investigated. Special attention is given to the surface pattern parameter and hydrodynamic roughness parameter.

Non-Newtonian Thermal Elastohydrodynamic Lubrication

1991 ◽  
Vol 113 (2) ◽  
pp. 390-396 ◽  
Author(s):  
P. C. Sui ◽  
F. Sadeghi
Keyword(s):  
Film Thickness ◽  
Numerical Solution ◽  
Reynolds Equation ◽  
Fluid Model ◽  
Traction Force ◽  
Elastohydrodynamic Lubrication ◽  
Simultaneous System ◽  
Energy Equations ◽  
Rheology Model ◽  
Generalized Reynolds Equation

A numerical solution to the problem of thermal and non-Newtonian fluid model in elastohydrodynamic lubrication is presented. The generalized Reynolds equation was modified by the Eyring rheology model to incorporate the non-Newtonian effects of the fluid. The simultaneous system of modified Reynolds, elasticity and energy equations were numerically solved for the pressure, temperature and film thickness. Results have been presented for loads ranging from W = 7 × 10−5 to W = 2.3 × 10−4 and the speeds ranging from U* = 2 × 10−11 to U* = 6 × 10−11 at various slip conditions. Comparison between the isothermal and thermal non-Newtonian traction force has also been presented.

Axisymmetric flow near the critical point on the moving boundary

2010 ◽  
Vol 7 ◽  
pp. 182-190
Author(s):  
I.Sh. Nasibullayev ◽  
E.Sh. Nasibullaeva
Keyword(s):  
Fluid Flow ◽  
Finite Difference ◽  
Boundary Conditions ◽  
Numerical Solution ◽  
Axial Velocity ◽  
Moving Boundary ◽  
Axisymmetric Flow ◽  
Boundary Motion ◽  
Newton Raphson ◽  
Raphson Method

In this paper the investigation of the axisymmetric flow of a liquid with a boundary perpendicular to the flow is considered. Analytical equations are derived for the radial and axial velocity and pressure components of fluid flow in a pipe of finite length with a movable right boundary, and boundary conditions on the moving boundary are also defined. A numerical solution of the problem on a finite-difference grid by the iterative Newton-Raphson method for various velocities of the boundary motion is obtained.

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