Analysis of Two Surfaces under Viscoelastic Contact

2013 ◽  
Vol 818 ◽  
pp. 77-82
Author(s):  
M. Mongkolwongrojn ◽  
J. Panichakorn ◽  
S. Supawanich ◽  
S. Chutima
Keyword(s):  
Film Thickness ◽  
Viscoelastic Material ◽  
Contact Region ◽  
Elastohydrodynamic Lubrication ◽  
Material Behaviors ◽  
Minimum Film Thickness ◽  
Heavy Loads ◽  
Element Technique ◽  
Cylindrical Roller ◽  
Viscoelastic Contact

This paper presents the analysis of the contact surfaces between a rigid cylinder and a soft plate for viscoelastic material. The contact pressure and deformation of the plate in contact region were determined using finite element technique. Moreover, the characteristics of two surfaces of cylindrical roller and plate under elastohydrodynamic lubrication with nonNewtonian fluid were examined using finite difference technique with full adaptive multigrid method . In this study the simulation of viscoelastic material in contact was under taken to determine the effects of material behaviors on the deformation of plate compared to the elastic materials. The results indicated that the deformation shapes were nonlinearly dependent with the applied loads. Furthermore, the deformation of elastic material would reach a certain value in a period of time whereas the deformation of viscoelastic material was increased inconsistently with time. The film pressure and film thickness profiles in the contact regime were investigated at various loads. The minimum film thickness occurs near the trailing edge of contact region and becomes very small under heavy loads.

Thermal Non-Newtonian Elastohydrodynamic Lubrication of Rolling Line Contacts

1991 ◽  
Vol 113 (3) ◽  
pp. 481-491 ◽  
Author(s):  
H. Salehizadeh ◽  
N. Saka
Keyword(s):  
Film Thickness ◽  
Contact Region ◽  
Elastohydrodynamic Lubrication ◽  
Pressure Profile ◽  
Shear Stresses ◽  
Hertz Contact ◽  
Minimum Film Thickness ◽  
Line Contacts ◽  
Pressure Spike ◽  
Heavy Loads

The two-dimensional thermal elastohydrodynamic equations were numerically solved for a Ree-Eyring type lubricant under pure rolling conditions. Profiles of lubricant pressure, film thickness, and temperature were obtained for medium to heavy loads and moderate to high rolling speeds. The pressure results generally show a small secondary peak near the outlet, but at the highest load considered no pressure spike is obtained and the pressure profile is almost Hertzian. The film thickness results show an increase in minimum film thickness with increasing rolling speeds, but at a lesser rate than those predicted for a Newtonian fluid under isothermal conditions. It is found that unless the lubricant becomes non-Newtonian in the inlet region, the reduction in minimum film thickness at high rolling speeds is completely due to thermal effect. The lubricant temperature profile and the amount of heat generated and dissipated in the contact region were also calculated. The lubricant temperature reaches a maximum just before the entrance to the Hertz contact region. Both shear and compression heating are found to be important in raising the lubricant temperature in the inlet. As the lubricant enters the Hertz contact zone, the temperature first drops rapidly, because of the rapid heat conduction to the rollers, and then remains almost constant for most of the Hertz contact. Near the exit where the pressure gradients are large, the lubricant temperature drops rapidly below the ambient because of lubricant expansion. The lubricant then heats up rapidly before leaving the contact area as a result of heat generated by shear stresses.

Rough Soft-EHL with Non-Newtonian Lubricant

2015 ◽  
Vol 736 ◽  
pp. 57-63
Author(s):  
Panichakorn Jesda ◽  
Wongseedakeaw Khanittha
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Film Thickness ◽  
Modulus Of Elasticity ◽  
Contact Region ◽  
Elastohydrodynamic Lubrication ◽  
Film Pressure ◽  
Coefficient Increase ◽  
Minimum Film Thickness ◽  
Effect Of Surface

This paper presents the effect of surface roughness on soft elastohydrodynamic lubrication in circular contact with non-Newtonian lubricant. The time independent modified Reynolds equation, elastic equation and lubricant viscosity equation were formulated for compressible fluid. Perturbation method, Newton-Raphson method, finite different method and full adaptive multigrid method were implemented to obtain the film pressure, film thickness profiles and friction coefficient in the contact region at various the amplitude of surface roughness, surface speed of sphere, modulus of elasticity and radius of sphere. The simulation results showed that the film thickness in contact region depended on the profile of surface roughness. The minimum film thickness decreased but maximum film pressure and friction coefficient increase when the amplitude of surface roughness and modulus of elasticity increased. For increasing surface speeds, the minimum film thickness and friction coefficient increase but maximum film pressure decreases. When radius of sphere increases, the minimum film thickness increases but maximum film pressure and friction coefficient decrease.

Effect of Nano and Micro Particle Additives on Rough Surface TEHL with Non-Newtonian Lubricant

2015 ◽  
Vol 736 ◽  
pp. 45-52
Author(s):  
Panichakorn Jesda
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Contact Region ◽  
Elastohydrodynamic Lubrication ◽  
Approximation Technique ◽  
Thermal Enhancement ◽  
Friction Heating ◽  
Load Carrying ◽  
Coefficient Increase ◽  
Minimum Film Thickness

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" />This paper presents the results of a analysis of rough thermo-elastohydrodynamic lubrication (TEHL) of line contact with non-Newtonian lubricant blended with Al2O3nanoparticles and MoS2 microparticles. The simultaneous systems of time independent modified Reynolds equation, elasticity equation, load carrying with micro particle equation and energy equation were solved numerically using multigrid multilevel with full approximation technique. In this study, the effect of Al2O3nanoparticle and MoS2microparticle additives and surface roughness were implemented to obtain film thickness, film pressure, film temperature, friction coefficient and load carrying with microparticle in the contact region. The simulation results showed that the maximum film temperature and friction coefficient increase slightly but the minimum film thickness decreases slightly with an increase in Al2O3nanoparticle concentration due to thermal enhancement of nanofluid. For increasing of microparticle concentration, the minimum film thickness and friction coefficient decrease because the increasing of friction heating of MoS2microparticle.

Analysis of the lubricating mechanism for tilting rollers in rolling bearings

2011 ◽  
Vol 225 (11) ◽  
pp. 1059-1070 ◽  
Author(s):  
X-L Liu ◽  
P Yang ◽  
P-R Yang
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Grid Method ◽  
Infinite Plane ◽  
Rolling Bearings ◽  
Velocity Parameter ◽  
Light Load ◽  
Minimum Film Thickness ◽  
Cylindrical Roller ◽  
Lubricating Mechanism

In practice, the tilting roller occurs widely in rolling bearings. In order to investigate the lubricating mechanism of tilting rollers in rolling bearings, a contact between a tilting cylindrical roller and an infinite plane is assumed in the present paper. Using the multi-grid method, a numerical solution has been obtained for the isothermal elastohydrodynamic lubrication of the contact. The film thickness and pressure with different tilt angles have been given. Results show that the property of the tilting roller’s lubrication is different from that of the parallel roller contact investigated in the past, and asymmetry is common both for the film thickness and the oil pressure under tilting conditions. Moreover, the larger the tilt angle, the smaller the minimum film thickness, and the more easily the local wear occurs in bearings. The effects of the maximum Hertzian pressure, velocity parameter, and length and end profile radius of the roller on the lubricating performance of the contact have been discussed. The conclusion can be made that better lubrication of tilting roller contact needs light load, high velocity parameter, short length, and larger end profile radius of the roller. Comparisons between the starved and fully flooded lubrication in the tilting roller contact have been given, and it has been found that starvation status can worsen the lubrication and reduce the life of roller bearings.

Effects of Surface Roughness on Elastohydrodynamic Lubrication in Elliptical Contact with Non-Newtonian Fluids

2012 ◽  
Vol 482-484 ◽  
pp. 1057-1061
Author(s):  
Sountaree Rattapasakorn ◽  
Jesda Panichakorn ◽  
Mongkol Mongkolwongrojn
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Film Thickness ◽  
Contact Region ◽  
Elastohydrodynamic Lubrication ◽  
Film Pressure ◽  
Minimum Film Thickness ◽  
Roughness Amplitude ◽  
Elliptical Contact ◽  
Effect Of Surface

This paper presents the effect of surface roughness on the performance characteristics of elastohydrodynamic lubrication with non-Newtonian fluid base on Carreau viscosity model in elliptical contact. The time independent modified Reynolds equation and elastic equation were formulated for compressible fluid. Perturbation method, Newton Raphson method and full adaptive multigrid method were implemented to obtain the film pressure, film thickness profiles and friction coefficient in the contact region at various amplitude of combined surface roughness, applied loads, speeds and elliptic ratio. Simulation results show surface roughness amplitude has significant affected the film pressure in the contact region. The minimum film thickness decreases but friction coefficient increases when the combined roughness and applied loads increases. The minimum film thickness and friction coefficient both increase as the relative velocity of the ball and the plate is increase. For increasing the elliptic ratio, the minimum film thickness increases but the friction coefficient decreases.

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.

Influence of Surface Waviness on the Thermal Elastohydrodynamic Lubrication of an Eccentric-Tappet Pair

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
J. Wang ◽  
C. H. Venner ◽  
A. A. Lubrecht
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Surface Waviness ◽  
Film Pressure ◽  
Oil Film ◽  
Working Cycle ◽  
Temperature Oscillations ◽  
Minimum Film Thickness ◽  
Traction Coefficient ◽  
Oil Film Pressure

The effect of single-sided and double-sided harmonic surface waviness on the film thickness, pressure, and temperature oscillations in an elastohydrodynamically lubricated eccentric-tappet pair has been investigated in relation to the eccentricity and the waviness wavelength. The results show that, during one working cycle, the waviness causes significant fluctuations of the oil film, pressure, and temperature, as well as a reduction in minimum film thickness. Smaller wavelength causes more dramatic variations in oil film. The fluctuations of the pressure, film thickness, temperature, and traction coefficient caused by double-sided waviness are nearly the same compared with the single-sided waviness, but the variations are less intense.

Film thickness in elastohydrodynamically lubricated slender elliptic contacts: Part I – numerical studies of central film thickness

2021 ◽  
pp. 135065012110477
Author(s):  
Marius Wolf ◽  
Sergey Solovyev ◽  
Fatemi Arshia
Keyword(s):  
Film Thickness ◽  
State Of The Art ◽  
Experimental Studies ◽  
Elastohydrodynamic Lubrication ◽  
Large Parameter ◽  
Numerical Studies ◽  
Minimum Film Thickness ◽  
Subsequent Publication ◽  
New Formula ◽  
Increasing Load

In this paper, analytical equations for the central film thickness in slender elliptic contacts are investigated. A comparison of state-of-the-art formulas with simulation results of a multilevel elastohydrodynamic lubrication solver is conducted and shows considerable deviation. Therefore, a new film thickness formula for slender elliptic contacts with variable ellipticity is derived. It incorporates asymptotic solutions, which results in validity over a large parameter domain. It captures the behaviour of increasing film thickness with increasing load for specific very slender contacts. The new formula proves to be significantly more accurate than current equations. Experimental studies and discussions on minimum film thickness will be presented in a subsequent publication.

Roughness Amplitude Reduction Under Non-Newtonian EHL Conditions

2005 ◽  
Author(s):  
A. D. Chapkov ◽  
C. H. Venner ◽  
A. A. Lubrecht
Keyword(s):  
Film Thickness ◽  
Pressure Fluctuations ◽  
Elastohydrodynamic Lubrication ◽  
Operating Conditions ◽  
Quantitative Prediction ◽  
Point Contacts ◽  
Minimum Film Thickness ◽  
Roughness Amplitude ◽  
Average Film Thickness ◽  
Ehl Contact

The influence of surface roughness on the performance of bearings and gears operating under ElastoHydrodynamic Lubrication (EHL) conditions has become increasingly important over the last decade, as the average film thickness decreased due to various influences. Surface features can reduce the minimum film thickness and thus increase the wear. They can also increase the temperature and the pressure fluctuations, which directly affects the component life. In order to describe the roughness geometry inside an EHL contact, the amplitude reduction of harmonic waviness has been studied over the last ten years. This theory currently allows a quantitative prediction of the waviness amplitude and includes the influence of wavelength and contact operating conditions. However, the model assumes a Newtonian behaviour of the lubricant. The current paper makes a first contribution to the extension of the roughness amplitude reduction for EHL point contacts including non-Newtonian effects.

Effect of oil starvation on the isothermal impact problem

2017 ◽  
Vol 232 (10) ◽  
pp. 1332-1339
Author(s):  
Duohuan Wu ◽  
Jing Wang ◽  
Peiran Yang ◽  
Ton Lubrecht
Keyword(s):  
Film Thickness ◽  
Pressure Gradient ◽  
Thickness Distribution ◽  
Elastohydrodynamic Lubrication ◽  
Maximum Pressure ◽  
Numerical Techniques ◽  
Minimum Film Thickness ◽  
The Impact ◽  
Impact Motion ◽  
Impact Problem

In this study, the effect of oil starvation on isothermal elastohydrodynamic lubrication of an impact motion is explored with the aid of numerical techniques. During the impact process, on comparison with the fully lubricated results, the pressure and film thickness are much lower and the entrapped film shape does not happen. The rebound is delayed by the oil starvation assumption. During the rebound process, a periphery entrapment is seen in the starved film thickness distribution. Under the starved condition, the maximum pressure gradient is higher. The central film thickness and minimum film thickness exhibit different variations compared with the results by fully flooded assumption.

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