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 Thermal Properties of a Coated Elastohydrodynamic Lubrication Line Contact Under Various Slide-to-Roll Ratios

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Huaiju Liu ◽  
Caichao Zhu ◽  
Zonglin Gu ◽  
Zhanjiang Wang ◽  
Jinyuan Tang
Keyword(s):  
Mechanical Properties ◽  
Thermal Properties ◽  
Elastohydrodynamic Lubrication ◽  
Temperature Fields ◽  
Line Contact ◽  
Oil Film ◽  
Line Contacts ◽  
Energy Equations ◽  
Thermal Conductivities

A numerical thermal elastohydrodynamic lubrication (EHL) model is developed for coated line contacts by considering both the mechanical properties and the thermal properties of the coating and the substrate. The temperature fields within the oil film and within the solids are solved by deriving the energy equations for the solids and the oil film. Heat continuity conditions are satisfied at the interfaces between the solids and the oil film, and the coating/substrate interfaces. Effects of the slide-to-roll ratio (SR), the thermal conductivities of the coating bodies, and the oil film on temperature fields are studied.

Wildhaber-Novikov Circular Arc Gears: Elastohydrodynamics

1993 ◽  
Vol 115 (3) ◽  
pp. 487-492 ◽  
Author(s):  
H. P. Evans ◽  
R. W. Snidle
Keyword(s):  
Film Thickness ◽  
Elastic Deformation ◽  
Elastohydrodynamic Lubrication ◽  
Major Axis ◽  
Operating Conditions ◽  
Circular Arc ◽  
Rolling Velocity ◽  
Oil Film ◽  
Practical Design ◽  
Thinning Effect

The paper describes an elastohydrodynamic lubrication (EHL) analysis of heavily loaded contacts between the teeth of Wildhaber-Novikov (W-N) circular arc gears. The contacts occurring in gears of this type are elliptical in shape with lubricant entrainment in the direction of the major axis of the contact. The results shown refer to a particular practical design and cover a range of operating conditions encountered in practice. Because of the high rolling velocity in W-N gears a relatively thick oil film is predicted over most of the contact. Severe thinning of the film occurs at the sides of the contact, however. Results of the full EHL analysis are compared with predictions using a published film thickness formula based upon analysis of moderately loaded elliptical contacts. It is suggested that the side-thinning effect is dependent upon the relative elastic deformation occurring in the contact.

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]

Influence of Different Viscosity Lubricant to Finite Line Contacts on Elastohydrodynamic Lubrication (EHL) under Oscillating

2012 ◽  
Vol 538-541 ◽  
pp. 1939-1944
Author(s):  
Yan Fei Wang ◽  
Tong Shu Hua ◽  
Hao Yang Sun
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Oil Film ◽  
Entrainment Velocity ◽  
Finite Line Contact ◽  
Line Contacts ◽  
Finite Line ◽  
Contact Roller ◽  
Two Parameters ◽  
Experimental Rig

To make further researches into the elastohydrodynamic lubrication properties of a finite line contact roller, oscillating experiments were carried out on made overload experimental rig for oil film measurement using optical interference technique. Film thickness and shape were measured in two kinds of viscosity polyisobutylene. This study indicates that both lubricant viscosity and roller entrainment velocity play an important role on EHL of finite line contacts. On motion, the more increase in viscosity or speed, the thicker the oil film thickness, simultaneity edge effect is distinctly intensified and film thickness increases less on roller end, difference of the film thickness is increased between roller end and the central. Above two parameters are significant for logarithmic profile roller in crowning design.

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 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.

The Application of Newton-Raphson Method to Thermal Elastohydrodynamic Lubrication of Line Contacts

1994 ◽  
Vol 116 (4) ◽  
pp. 733-740 ◽  
Author(s):  
R. Wolff ◽  
A. Kubo
Keyword(s):  
Film Thickness ◽  
Thermal Effects ◽  
Elastohydrodynamic Lubrication ◽  
Numerical Approach ◽  
Heavy Load ◽  
Rolling Velocity ◽  
Line Contacts ◽  
Pressure Spike ◽  
Newton Raphson ◽  
Raphson Method

The Newton-Raphson method was applied to solve the thermal EHD lubrication model of line contacts. By accounting for thermal effects in the Newton-Raphson scheme, a very stable numerical approach was obtained. Two models with viscosity constant and variable across the oil film were developed. The results under extremely heavy conditions of dimensionless load W = 52 * 10−5 (pH = 2 GPa) and dimensionless rolling velocity U = 20 * 10−11 are presented. They show that even for pure rolling, but under heavy load and high rolling velocity conditions, the thermal effects significantly reduce the minimum film thickness. The distributions of pressure, film thickness, and temperature for two rolling velocities and various loads are presented. They indicate that under high rolling velocity conditions the thermal effects have a strong influence on a pressure spike.

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.

Influence of piezo-viscous behavior and load on the effectiveness of inlet zone bump in unidirectional pure sliding EHL line contacts

2018 ◽  
Vol 70 (9) ◽  
pp. 1766-1773
Author(s):  
Punit Kumar
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Governing Equations ◽  
Local Pressure ◽  
Content Type ◽  
Elasticity Equations ◽  
Line Contacts ◽  
Lower Load ◽  
Inlet Zone ◽  
Lubricant Viscosity

Purpose The purpose of this paper is to introduce the concept of stationary inlet zone bump (IZB) for film thickness enhancement in unidirectional pure sliding elastohydrodynamic lubrication (EHL) line contacts and to investigate the effects of maximum Hertzian pressure (load) and piezo-viscous response on the effectiveness of IZB. Design/methodology/approach The numerical analysis involves the solution of Reynolds and elasticity equations. The well-established Doolittle–Tait equations are used herein to determine the lubricant viscosity and density as functions of local pressure, while the Carreau model is used to describe the lubricant rheology. The IZB is assumed to have a sinusoidal profile and it is present on the stationary surface. The governing equations are discretized using finite difference scheme and solved using the Newton–Raphson technique. Findings Two test oils, L7808 and SR600, with linear and exponential piezo-viscous responses in the inlet zone are considered here for comparison. The effectiveness of IZB in terms of film thickness enhancement is found to be more for SR600. Besides, IZB is found to be more effective at lower values of maximum Hertzian pressure. The bump needs to shift downstream at higher load to be as effective as at lower load. Originality/value This is the first paper to simulate EHL characteristics in the presence of a stationary IZB and to study the effect of various parameters on EHL effectiveness. The film thickness enhancement obtained here is remarkable and hence it is a novel and valuable contribution.

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.

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