Surface Roughness and Structural Inertia in a Mode-Based Mass-Conserving Elastohydrodynamic Lubrication Model

1997 ◽  
Vol 119 (3) ◽  
pp. 449-455 ◽  
Author(s):  
S. Boedo ◽  
J. F. Booker
Keyword(s):  
Surface Roughness ◽  
Performance Evaluation ◽  
Film Thickness ◽  
Computational Model ◽  
Elastohydrodynamic Lubrication ◽  
Mode Shapes ◽  
Connecting Rod ◽  
Roughness Effects ◽  
Structural Inertia ◽  
Structural Motion

Detailed formulations are presented for a mass-conserving, mode-based computational model which includes effects of structural inertia and surface roughness. Performance evaluation of a big end connecting rod hearing is shown to require only a few mode shapes, from which it is found that body forces arising from structural motion strongly influence film thickness history at operating engine speeds. Surface roughness effects on nominal film thickness are found to be small, even in assumed regions of partial lubrication.

A Mode-Based Elastohydrodynamic Lubrication Model With Elastic Journal and Sleeve

1999 ◽  
Vol 122 (1) ◽  
pp. 94-102 ◽  
Author(s):  
S. Boedo ◽  
J. F. Booker
Keyword(s):  
Performance Evaluation ◽  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Relative Displacement ◽  
Mode Shapes ◽  
Combined Effects ◽  
Connecting Rod ◽  
Film Pressure ◽  
Bearing System

A mass-conserving, mode-based elastohydrodynamic lubrication model, which includes combined effects of journal and sleeve elasticity, is described. Application to a sample cylindrical bearing system (geometrically similar to automotive main and connecting rod bearings) shows that relative displacement of an elastic journal and sleeve can be represented by a set of mode shapes which are qualitatively similar to those obtained with a rigid journal, while the corresponding mode eigenvalues are found to be dependent on journal elasticity. Performance evaluation under steady and pure squeeze loading shows that a sufficiently compliant hollow journal can reduce film pressure and improve film thickness when compared with its rigid counterpart. [S0742-4787(00)01301-1]

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.

Theoretical Investigation in an Artificial Hip Joint under Elastohydrodynamic Lubrication

2015 ◽  
Vol 736 ◽  
pp. 140-145
Author(s):  
Khanittha Wongseedakaew
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Hip Joint ◽  
Initial Conditions ◽  
Surface Condition ◽  
Elastohydrodynamic Lubrication ◽  
Human Movement ◽  
Approximation Technique ◽  
Artificial Hip Joint ◽  
Artificial Hip

This paper describes the transient analysis of artificial hip joint during human movement under elastohydrodynamic lubrication (EHL) with non-Newtonian lubricants based on a Carreau model. During walking, the load and velocity are varying with time. The numerical schemes employed perturbation method, Newton-Raphson method and multi-grid multilevel with full approximation technique to solve the time-dependent modified Reynolds equation and elasticity equation with initial conditions. The aim of this study was investigated the characteristics of elastohydrodynamic lubrication, profile of film pressure and film thickness profile in human artificial hip joint during human movement. Numerical results show the transient film thicknessincreased and then decreased because of reverse motion. In smooth surface condition, film thickness for Newtonian fluids is slightly higher than the film thickness for non-Newtonian fluid. The amplitude of surface roughness has significant effect on the film thickness,the minimum film thickness decreased when the amplitude of surface roughness increases.

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

Film Thickness and Asperity Load Formulas for Line-Contact Elastohydrodynamic Lubrication With Provision for Surface Roughness

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
M. Masjedi ◽  
M. M. Khonsari
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Reynolds Equation ◽  
Surface Deformation ◽  
Elastohydrodynamic Lubrication ◽  
Load Ratio ◽  
Material Surface ◽  
Line Contact ◽  
Wide Range ◽  
Minimum Film Thickness

Three formulas are derived for predicting the central and the minimum film thickness as well as the asperity load ratio in line-contact EHL with provision for surface roughness. These expressions are based on the simultaneous solution to the modified Reynolds equation and surface deformation with consideration of elastic, plastic and elasto-plastic deformation of the surface asperities. The formulas cover a wide range of input and they are of the form f(W, U, G, σ¯, V), where the parameters represented are dimensionless load, speed, material, surface roughness and hardness, respectively.

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.

Sign in / Sign up

Export Citation Format

Share Document