Transient EHL of Two Surfaces under Elliptical Contact with Non-Newtonian Lubricant

2012 ◽  
Vol 452-453 ◽  
pp. 1291-1295 ◽  
Author(s):  
Mongkolwongrojn Mongkol ◽  
Panichakorn Jesda
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Research Work ◽  
Elastohydrodynamic Lubrication ◽  
Coefficient Increase ◽  
Minimum Film Thickness ◽  
Speed Change ◽  
Elliptical Contact ◽  
Raphson Method ◽  
Sudden Load

This paper presents the effects of a sudden load change and sudden speed change on the performance characteristics of two surfaces under elliptical contact with elastohydrodynamic lubrication. The non-Newtonian lubricant for the research work are modeled based on Carreau viscosity model. The time dependent modified Reynolds equation and elastic equation were formulated for compressible fluid. Perturbation method, Newton Raphson method and full adaptive multigrid method were implemented and solved to obtain the film pressure, film thickness profiles and friction coefficient in the contact regime at various applied loads and speeds. Simulation results show the friction coefficient increase significantly under sudden loads. The minimum film thickness and friction coefficient both decrease significantly as speed is decreased.

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.

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.

Comparison of tribological performance of roller follower and flat follower under mixed elastohydrodynamic lubrication regime

2016 ◽  
Vol 231 (8) ◽  
pp. 986-996 ◽  
Author(s):  
Amir Torabi ◽  
Saleh Akbarzadeh ◽  
Mohammadreza Salimpour
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Numerical Model ◽  
Film Thickness ◽  
Thermal Effects ◽  
Elastohydrodynamic Lubrication ◽  
Hydrodynamic Pressure ◽  
Minimum Film Thickness ◽  
Cam Follower ◽  
Key Parameter

In this study, a numerical model is developed to show the performance improvement of a cam–follower mechanism when using a roller type follower compared to the flat-faced follower. Nonconformal geometry besides the thermal effects due to the shearing of the lubricant film results in formation of a thin film in which the asperities contribute in carrying the load. The numerical model is developed in which the geometry, load, speed, lubricant properties, and the surface roughness profile is taken as input and the film thickness and friction coefficient as a function of cam angle are predicted. The asperities are assumed to have elastic, elasto-plastic, and plastic deformation. Simulation results indicated that the thermal effects cannot be neglected. Surface roughness is also a key parameter that affects the pressure distribution, film thickness, and friction coefficient. Finally, asperity and hydrodynamic pressure is reported and the performance of the two mechanisms is compared. Roller follower has a considerable preference in terms of friction coefficient compared to flat-faced follower. The minimum film thickness, however, is slightly larger in the flat follower.

Transient Thermo-Elastohydrodynamic Lubrication of Rough Surface in Soft Material

2013 ◽  
Vol 651 ◽  
pp. 505-510 ◽  
Author(s):  
Khanittha Wongseedakaew
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Film Thickness ◽  
Rough Surface ◽  
Contact Region ◽  
Elastohydrodynamic Lubrication ◽  
Soft Material ◽  
Pressure Profiles ◽  
Finite Different Method ◽  
Raphson Method

This paper presents the effects of transient rough surface thermo-elastohydrodynamic lubrication (TEHL) of rollers for soft material with non-Newtonian fluid base on power law model. The time independent modified Reynolds equation, energy equation and elasticity equation were solved numerically using finite different method, Newton-Raphson method and multigrid multilevel method to obtain the film pressure profiles, film thickness profiles and friction coefficient in the contact region. The simulation results show surface roughness has effect on film thickness but its effect on film temperature is insignificant. The minimum film thickness decreases while the coefficient increases when the amplitude of surface roughness increases. Meanwhile, increasing applied loads causes the friction coefficient to decrease.

Theoretical Investigation of Transient Lubrication in Spur Gear

2013 ◽  
Vol 420 ◽  
pp. 36-41
Author(s):  
Jesda Panichakorn ◽  
Khanittha Wongseedakaew
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Initial Conditions ◽  
Contact Region ◽  
Elastohydrodynamic Lubrication ◽  
Spur Gear ◽  
Gear Teeth ◽  
Pressure Profiles ◽  
Finite Different Method ◽  
Raphson Method

This paper presents performance characteristics of transient thermo-elastohydrodynamic lubrication (TEHL) in line contact with Newtonian fluids. The time-dependent modified Reynolds equation, energy equation and elasticity equation with initial conditions were solved numerically using finite different method, Newton-Raphson method and multigrid multilevel method for an involutes spur gear to obtain the film pressure profiles, film thickness profiles, film temperature and friction coefficient in the contact region. In this analysis, the load is applied on either two pairs or one pair of gear teeth. The simulation results show that at approach point, the film thickness is minimized and film temperature rapidly increases. Film temperature and friction coefficient were suddenly increase when the transition from two pairs to one pair and vice versa are modeled as a step variation of load. The friction coefficient and film temperature were occurrence at pitch point. Film temperature and friction coefficient increase but film thickness decreases when applied load increases. For increasing of speeds, film thickness and film temperature increase but friction coefficient decreses.

scholarly journals A thermal resistances-based approach for thermal-elastohydrodynamic calculations in point contacts

2017 ◽  
Vol 232 (11) ◽  
pp. 2088-2102 ◽  
Author(s):  
Eduardo de la Guerra Ochoa ◽  
Javier Echávarri Otero ◽  
Enrique Chacón Tanarro ◽  
Benito del Río López
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Thermal Effects ◽  
Good Accuracy ◽  
Computational Cost ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Point Contacts ◽  
New Approach ◽  
Ball On Disc

This article presents a thermal resistances-based approach for solving the thermal-elastohydrodynamic lubrication problem in point contact, taking the lubricant rheology into account. The friction coefficient in the contact is estimated, along with the distribution of both film thickness and temperature. A commercial tribometer is used in order to measure the friction coefficient at a ball-on-disc point contact lubricated with a polyalphaolefin base. These data and other experimental results available in the bibliography are compared to those obtained by using the proposed methodology, and thermal effects are analysed. The new approach shows good accuracy for predicting the friction coefficient and requires less computational cost than full thermal-elastohydrodynamic simulations.

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.

Size effect on thermal elastohydrodynamic lubrication of industrial chain bush-pin hinge pair

2019 ◽  
Vol 71 (9) ◽  
pp. 1080-1085 ◽  
Author(s):  
Mingyu Zhang ◽  
Jing Wang ◽  
Yi Liu ◽  
Longjie Dai ◽  
Zhaohua Shang
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Temperature Rise ◽  
Elastohydrodynamic Lubrication ◽  
Curvature Radius ◽  
Line Contact ◽  
Content Type ◽  
Oil Film ◽  
Industrial Chain ◽  
Infinite Line

Purpose The purpose of this paper is to use elastohydrodynamic lubrication (EHL) theory to study the variation of the equivalent curvature radius “R” on the change of oil film thickness, pressure, temperature rise and friction coefficient in the contact zone between bush-pin in industrial chain drive. Design/methodology/approach In this paper, the contact between bush and pin is simplified as infinitely long line contact. The lubrication state is studied by numerical simulation using steady-state line contact thermal EHL. The two constitutive equations, namely, Newton fluid and Ree–Eyring fluid are used in the calculations. Findings It is found that with the increase of equivalent curvature radius, the thickness of oil film decreases and the temperature rise increases. Under the same condition, the friction coefficient of Newton fluid is higher than that of Ree–Eyring fluid. When the load increases, the oil film thickness decreases, the temperature rise increases and the friction coefficient decreases; and the film thickness increases with the increase of the entraining speed under the condition “R < 1,000 mm”. Research limitations/implications The infinite line contact assumption is only an approximation. For example, the distances between the two inner plates are 5.72 mm, by considering the two parts assembled into the inner plates, the total length of the bush is less than 6 mm. The diameter of the pin and the bore diameter of the bush are 3.28 and 3.33 mm. However, the infinite line contact is also helpful in understanding the general variation of oil film characteristics and provides a reference for the future study of finite line contact of chain problems. Originality/value The change of the equivalent radius R on the variation of the oil film in the contact of the bush and the pin in industrial chain drive was investigated. The size effect influences the lubrication characteristic greatly in the bush-pin pair.

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