EFFECTS OF SURFACE FORCES ON SQUEEZE EHL MOTION BETWEEN ELASTIC BALL AND ELASTIC COATED SURFACE

2016 ◽  
Vol 40 (5) ◽  
pp. 821-833
Author(s):  
Li-Ming Chu ◽  
Jaw-Ren Lin ◽  
Hsiang-Chen Hsu ◽  
Yuh-Ping Chang
Keyword(s):  
Elastic Modulus ◽  
Film Thickness ◽  
Pressure Distribution ◽  
Contact Region ◽  
Load Condition ◽  
Elastohydrodynamic Lubrication ◽  
Surface Force ◽  
Surface Forces ◽  
Operating Conditions ◽  
Transient Pressure

The effects of surface forces (SF) and coated layers (CL) on pure squeeze elastohydrodynamic lubrication (EHL) motion of circular contacts are explored under constant load condition by using the finite difference method (FDM) and the Gauss–Seidel iteration method. The transient pressure profiles, surface force, film shapes, and elastic deformation during the pure squeeze process under various operating conditions in the TFEHL regime are discussed. The simulation results reveal that the difference between SFEHL model and EHL model is apparent as the film thickness is thinner than 5 nm. The oscillation phenomena in pressure and film thickness come mainly from the action of solvation forces. At contact region, the greater elastic modulus and smaller coating thicknesses, the greater pressure distribution, and the smaller film thickness. The film thicknesses are found reverse at outside the contact zone. At the exit region, i.e. the minimum film thickness region, it is valid that the greater the elastic modulus and the smaller the coating thicknesses, the greater the solvation pressure distribution. The effects of surface forces become significant as the film thickness becomes thinner.

Effects of Surface Roughness and Surface Force on the Thin Film Elastohydrodynamic Lubrication of Circular Contacts

2012 ◽  
Vol 67 (6-7) ◽  
pp. 412-418
Author(s):  
Li-Ming Chu ◽  
Jaw-Ren Lin ◽  
Jiann-Lin Chen
Keyword(s):  
Thin Film ◽  
Surface Roughness ◽  
Film Thickness ◽  
Contact Region ◽  
Load Condition ◽  
Elastohydrodynamic Lubrication ◽  
Surface Force ◽  
Surface Forces ◽  
Hertzian Contact ◽  
Deformation Equation

The effects of surface roughness and surface force on thin film elastohydrodynamic lubrication (TFEHL) circular contact problems are analyzed and discussed under constant load condition. The multi-level multi-integration (MLMI) algorithm and the Gauss-Seidel iterative method are used to simultaneously solve the average Reynolds type equation, surface force equations, the load balance equation, the rheology equations, and the elastic deformation equation. The simulation results reveal that the difference between the TFEHL model and the traditional EHL model increase with decreasing film thickness. The effects of surface forces become significant as the film thickness becomes thinner. The surface forces have obvious effects in the Hertzian contact region. The oscillation phenomena in pressure and film thickness come mainly from the action of solvation forces

Elastohydrodynamic lubrication analysis of a functionally graded layered bearing surface, with particular reference to ‘cushion form bearings’ for artificial knee joints

2003 ◽  
Vol 217 (3) ◽  
pp. 191-198 ◽  
Author(s):  
S S Virdee ◽  
F C Wang ◽  
H Xu ◽  
Z M Jin
Keyword(s):  
Elastic Modulus ◽  
Film Thickness ◽  
Pressure Distribution ◽  
Single Layer ◽  
Elastohydrodynamic Lubrication ◽  
Functionally Graded ◽  
Operating Conditions ◽  
Knee Joints ◽  
Bearing Surface ◽  
Elasticity Equation

Elastohydrodynamic lubrication of a functionally graded layered (FGL) bearing surface, whose elastic modulus increases with depth from the bearing surface, was investigated in this study. The finite difference method was employed to solve the Reynolds equation, simultaneously with the elasticity equation of the bearing surface, under circular point contacts. The finite element method was adopted to solve the elasticity equation for the FGL bearing surface. The displacement coefficients thus obtained were used to calculate the elastic deformation of the bearing surface, required for the elastohydrodynamic lubrication analysis. Good agreement of the predicted film thickness and pressure distribution was obtained, between the present method and a previous study for a single layered bearing surface with a uniform elastic modulus. The general numerical methodology was then applied to an FGL bearing surface with both linear and exponential variations in elastic modulus, with particular reference to the ‘cushion form bearing’ for artificial knee joints. The predicted film thickness and pressure distribution were shown to be quite close to those obtained for a single layer under typical operating conditions representative of artificial knee joints, provided that the elastic modulus of the single layer was chosen to be the average elastic modulus of the graded layer.

Pure Squeeze Motion in a Magneto-Elastohydrodynamic Lubricated Spherical Conjunction

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Li-Ming Chu ◽  
Jaw-Ren Lin ◽  
Wang-Long Li ◽  
Yuh-Ping Chang
Keyword(s):  
Magnetic Field ◽  
Load Condition ◽  
Elastohydrodynamic Lubrication ◽  
Transverse Magnetic ◽  
Constant Load ◽  
Operating Conditions ◽  
Transient Pressure ◽  
Electrically Conducting ◽  
Pressure Profiles ◽  
Effective Lubricant

The pure squeeze magneto-elastohydrodynamic lubrication (MEHL) motion of circular contacts with an electrically conducting fluid in the presence of a transverse magnetic field is explored under constant load condition. The differences between classical elastohydrodynamic lubrication and MEHL are discussed. The results reveal that the effect of an externally applied magnetic field is equivalent to enhancing effective lubricant viscosity. Therefore, as the Hartmann number increases, the enhancing effect becomes more obvious. Furthermore, the transient pressure profiles, film shapes, normal squeeze velocities, and effective viscosity during the pure squeeze process under various operating conditions are discussed.

Effects of Surface Forces on Pure Squeeze Elastohydrodynamic Lubrication Motion of Circular Contacts with Coated Layer

2015 ◽  
Vol 642 ◽  
pp. 104-109
Author(s):  
Li Ming Chu ◽  
Wang Long Li ◽  
Qie Da Chen ◽  
Chi Chen Yu ◽  
Chi Yang Yeh
Keyword(s):  
Finite Element Method ◽  
Film Thickness ◽  
Load Condition ◽  
Elastohydrodynamic Lubrication ◽  
Constant Load ◽  
Surface Forces ◽  
The Finite Element Method ◽  
Coated Layer ◽  
The Difference ◽  
Solvation Forces

The effects of surface forces (SF) on pure squeeze elastohydrodynamic lubrication (EHL) motion of circular contacts with coated layer are explored under constant load condition by using the finite element method (FEM) and the Gauss-Seidel iteration method. The difference between SFEHL model and EHL model is apparent as the film thickness is thinner than 5 nm. The oscillation phenomena in pressure and film thickness come mainly from the action of solvation forces. The effects of surface forces become significant as the film thickness becomes thinner.

Rheological Characteristics for Thin Film Elastohydrodynamic Lubrication

2005 ◽  
Vol 21 (2) ◽  
pp. 77-84 ◽  
Author(s):  
H.-M. Chu ◽  
R. T. Lee ◽  
S. Y. Hu ◽  
Y.-P. Chang
Keyword(s):  
Thin Film ◽  
Film Thickness ◽  
Pressure Distribution ◽  
Relative Viscosity ◽  
Elastohydrodynamic Lubrication ◽  
Surface Forces ◽  
Hertzian Contact ◽  
Surface Films ◽  
Thin Film Lubrication ◽  
The Status

ABSTRACTThis paper uses three lubrication models to explore the differential phenomenon in the status of thin film lubrication (TFL). According to the viscous adsorption theory, the modified Reynolds equation for thin film elastohydrodynamic lubrication (TFEHL) is derived. In this theory, the film thickness between lubricated surfaces is simplified as three fixed layers across the film, and the viscosity and density of the lubricant vary with pressure in each layer. Under certain conditions, such as a rough or concentrated contact of a nominally flat surface, films may be of nanometer scale. The thin film elastohydrodynamic lubrication (EHL) analysis is performed on a surface forces (SF) model which includes van der waals and solvation forces. The results show that the proposed TFEHL model can reasonably calculate the film thickness and the average relative viscosity under thin film EHL. The adsorption layer thickness and the viscosity influence significantly the lubrication characteristics of the contact conjunction. The differences in pressure distribution and film shape between surface forces model and classical EHL model were obvious, especially in the Hertzian contact area. The solvation force has the greatest influence on pressure distribution.

Elastohydrodynamic Lubrication of Elliptical Contacts for Materials of Low Elastic Modulus I—Fully Flooded Conjunction

1978 ◽  
Vol 100 (2) ◽  
pp. 236-245 ◽  
Author(s):  
Bernard J. Hamrock ◽  
Duncan Dowson
Keyword(s):  
Elastic Modulus ◽  
Film Thickness ◽  
Pressure Distribution ◽  
Elastohydrodynamic Lubrication ◽  
Line Contact ◽  
Low Elastic Modulus ◽  
Minimum Film Thickness ◽  
Contour Plots ◽  
Order Of Magnitude ◽  
Ellipticity Parameter

Our earlier studies of elastohydrodynamic lubrication of conjunctions of elliptical form are applied to the particular and interesting situation exhibited by materials of low elastic modulus. By modifying the procedures we outlined in an earlier publication, the influence of the ellipticity parameter k and the dimensionless speed U, load W, and material G parameters on minimum film thickness for these materials has been investigated. The ellipticity parameter was varied from 1 (a ball-on-plate configuration) to 12 (a configuration approaching a line contact). The dimensionless speed and load parameters were varied by 1 order of magnitude. Seventeen different cases were used to generate the following minimum- and central-film-thickness relations: H˜min=7.43(1−0.85e−0.31k)U0.65W−0.21H˜c=7.32(1−0.72e−0.28k)U0.64W−0.22 Contour plots are presented that illustrate in detail the pressure distribution and film thickness in the conjunction.

Transient Air-Soft EHL of Rough Surface with Impact Sudden Load

2013 ◽  
Vol 394 ◽  
pp. 96-100
Author(s):  
Khanittha Wongseedakaew
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Rough Surface ◽  
Contact Region ◽  
Load Condition ◽  
Elastohydrodynamic Lubrication ◽  
Film Pressure ◽  
Pressure Profiles ◽  
The Impact ◽  
Sudden Load

This paper presents the effects of transient rough surface air-soft elastohydrodynamic lubrication (EHL) of rollers for soft material. The time independent modified Reynolds equation, and elasticity equation were solved numerically using finite different method, Newton-Raphson method and multigrid multilevel method to obtain the film pressure profiles and film thickness in the contact region. The effects of overload, surface roughness and time period are examined. The simulation results show surface roughness has effect on film thickness. The impact of sudden load condition is that the air film pressure increases but film thickness decreases. The minimum film thickness decreases when the amplitude of surface roughness increases. Increasing of impact from sudden loads resulted in minimal film thickness decrease.

Rough Air-Soft Elastohydrodynamic Lubrication

2013 ◽  
Vol 420 ◽  
pp. 30-35
Author(s):  
Khanittha Wongseedakaew ◽  
Jesda Panichakorn
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Modulus Of Elasticity ◽  
Contact Region ◽  
Elastohydrodynamic Lubrication ◽  
Multilevel Methods ◽  
Inlet Temperature ◽  
Film Pressure ◽  
Air Inlet ◽  
Air Film

This paper presents the effects of rough surface air-soft elastohydrodynamic lubrication (EHL) of rollers for soft material under the effect of air molecular slip. The time independent modified Reynolds equation and elasticity equation were solved numerically using finite different method, Newton-Raphson method and multigrid multilevel methods were used to obtain the film pressure profiles and film thickness in the contact region. The effects of amplitude of surface roughness, modulus of elasticity and air inlet temperature are examined. The simulation results showed surface roughness has effect on film thickness but it little effect to air film pressure. When the amplitude of surface roughness and modulus of elasticity increased, the air film thickness decreased but air film pressure increased. However, the air inlet temperature increased when the air film thickness increased.

A Starved Mixed Elastohydrodynamic Lubrication Model for the Prediction of Lubrication Performance, Friction and Flash Temperature With Arbitrary Entrainment Angle

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Wei Pu ◽  
Dong Zhu ◽  
Jiaxu Wang
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Flash Temperature ◽  
Machined Surface ◽  
Lubrication Performance ◽  
Wide Range ◽  
Starved Lubrication

In this study, a modified mixed lubrication model is developed with consideration of machined surface roughness, arbitrary entraining velocity angle, starvation, and cavitation. Model validation is executed by means of comparison between the obtained numerical results and the available starved elastohydrodynamic lubrication (EHL) data found from some previous studies. A comprehensive analysis for the effect of inlet oil supply condition on starvation and cavitation, mixed EHL characteristics, friction and flash temperature in elliptical contacts is conducted in a wide range of operating conditions. In addition, the influence of roughness orientation on film thickness and friction is discussed under different starved lubrication conditions. Obtained results reveal that inlet starvation leads to an obvious reduction of average film thickness and an increase in interasperity cavitation area due to surface roughness, which results in significant increment of asperity contacts, friction, and flash temperature. Besides, the effect of entrainment angle on film thickness will be weakened if the two surfaces operate under starved lubrication condition. Furthermore, the results show that the transverse roughness may yield thicker EHL films and lower friction than the isotropic and longitudinal if starvation is taken into account. Therefore, the starved mixed EHL model can be considered as a useful engineering tool for industrial applications.

CAE Correlation of Sealing Pressure of a Press-in-Place Gasket

2021 ◽  
Keyword(s):  
Internal Pressure ◽  
Pressure Distribution ◽  
Load Condition ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Test Results ◽  
Local Pressure ◽  
Cross Sectional ◽  
Pad Test ◽  
Sealing Pressure

The Press-in-Place (PIP) gasket is a static face seal with self-retaining feature, which is used for the mating surfaces of engine components to maintain the reliability of the closed system under various operating conditions. Its design allows it to provide enough contact pressure to seal the internal fluid as well as prevent mechanical failures. Insufficient sealing pressure will lead to fluid leakage, consequently resulting in engine failures. A test fixture was designed to simulate the clamp load and internal pressure condition on a gasket bolted joint. A Sensor pad using TEKSCAN equipment was used to capture the overall and local pressure distribution of the PIP gasket under various engine loading conditions. Then, the Sensor pad test results were compared with simulated CAE results from computer models. Through the comparisons, it is found that the gasket sealing pressure of test data and CAE data show good correlation for bolt load condition 500N when compared to internal pressure side load condition of 0.138 MPa & 0.276 MPa. Moreover, the gasket cross-sectional pressure distribution obtained by experimental tests and CAE models correlated very well with R2 ranging from 90 to 99% for all load cases. Both CAE and Sensor pad test results shows increase in sealing pressure when internal side pressure is applied to the gasket seal.

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