Lubrication of 2D Soft Elasto Hydrodynamic Contacts: Extension of the Amplitude Reduction Theory

2011 ◽  
Author(s):  
F. Mora ◽  
P. Sainsot ◽  
A. A. Lubrecht ◽  
Y. le Chenadec
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Lubricant Film ◽  
Operating Conditions ◽  
Quantitative Prediction ◽  
Reduction Theory ◽  
Lubricant Film Thickness

This paper is an extension of the Amplitude Reduction Theory to soft ElastoHydrodynamic contacts. The ART permits a quantitative prediction of the influence of surface roughness on the lubricant film thickness modification as a function of the operating conditions.

A Mixed-Lubrication Study of Journal Bearing Conformal Contacts

1997 ◽  
Vol 119 (3) ◽  
pp. 456-461 ◽  
Author(s):  
Qian (Jane) Wang ◽  
Fanghui Shi ◽  
Si C. Lee
Keyword(s):  
Film Thickness ◽  
Contact Pressure ◽  
Contact Area ◽  
Numerical Solutions ◽  
Mixed Lubrication ◽  
Lubricant Film ◽  
Operating Conditions ◽  
Asperity Contact ◽  
Lubricant Film Thickness ◽  
Asperity Contacts

Numerical analyses of finite journal bearings operating with large eccentricity ratios were conducted to better understand the mixed lubrication phenomena in conformal contacts. The average Reynolds equation derived by Patir and Cheng was utilized in the lubrication analysis. The influence function, calculated numerically using the finite element method, was employed to compute the bearing deformation. The effects of bearing surface roughness were incorporated in the present analysis for the calculations of the asperity contact pressure and the asperity contact area. The numerical solutions of the hydrodynamic and asperity contact pressures, lubricant film thickness, and asperity contact area were evaluated based on a simulated bearing-journal geometry. The calculations revealed that the asperity contact pressure may vary significantly along both the width and the circumferential directions. It was also shown that the asperity contacts and the lubricant film thickness were strongly dependent on the bearing width, asperity orientation, and operating conditions.

The Effects of Three-Dimensional Model Surface Roughness Features on Lubricant Film Thickness in EHL Contacts

2003 ◽  
Vol 125 (3) ◽  
pp. 533-542 ◽  
Author(s):  
Jian W. Choo ◽  
Romeo P. Glovnea ◽  
Andrew V. Olver ◽  
Hugh A. Spikes
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Three Dimensional ◽  
Lubricant Film ◽  
Imaging Method ◽  
Dimensional Model ◽  
Lubricant Film Thickness ◽  
Model Surface ◽  
Three Dimensional Model ◽  
Spacer Layer

The Spacer Layer Imaging method has been used to investigate the influence of three-dimensional roughness features on the thickness and shape of elastohydrodynamic (EHL) films. An array of near-hemispherical bumps was employed to represent asperities. A micro-EHL film developed at the bumps whose orientation depended on that of the inlet boundary at the location at which the bump had entered the contact. Rolling-sliding conditions induced a micro-EHL film with a classical horseshoe shape at the bumps. The flow of lubricant around the bumps appeared to differ between thin and thick films.

Numerical Solution of Mixed Thermal Elastohydrodynamic Lubrication in Point Contacts With Three-Dimensional Surface Roughness

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Xiaopeng Wang ◽  
Yuchuan Liu ◽  
Dong Zhu
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Three Dimensional ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Lubricant Film ◽  
Operating Conditions ◽  
Thickness Variation ◽  
Wide Range ◽  
Film Lubrication

Elastohydrodynamic lubrication (EHL) is a common mode of fluid-film lubrication in which many machine elements operate. Its thermal behavior is an important concern especially for components working under extreme conditions such as high speeds, heavy loads, and surfaces with significant roughness. Previous thermal EHL (TEHL) studies focused only on the cases with smooth surfaces under the full-film lubrication condition. The present study intends to develop a more realistic unified TEHL model for point contact problems that is capable of simulating the entire transition of lubrication status from the full-film and mixed lubrication all the way down to boundary lubrication with real machined roughness. The model consists of the generalized Reynolds equation, elasticity equation, film thickness equation, and those for lubricant rheology in combination with the energy equation for the lubricant film and the surface temperature equations. The solution algorithms based on the improved semi-system approach have demonstrated a good ability to achieve stable solutions with fast convergence under severe operating conditions. Lubricant film thickness variation and temperature rises in the lubricant film and on the surfaces during the entire transition have been investigated. It appears that this model can be used to predict mixed TEHL characteristics in a wide range of operating conditions with or without three-dimensional (3D) surface roughness involved. Therefore, it can be employed as a useful tool in engineering analyses.

scholarly journals The Effect of Texture Floor Profile on the Lubricant Film Thickness in a Textured Hard-On-Soft Bearing With Relevance to Prosthetic Hip Implants

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Quentin Allen ◽  
Bart Raeymaekers
Keyword(s):  
Film Thickness ◽  
Polyethylene Wear ◽  
Texture Feature ◽  
Lubricant Film ◽  
Operating Conditions ◽  
Design Parameters ◽  
Contact Friction ◽  
Hip Implants ◽  
Lubricant Film Thickness ◽  
Texture Parameters

Abstract Polyethylene wear debris limits the longevity of prosthetic hip implants. We design a pattern of axisymmetric texture features to increase hydrodynamic pressure and lubricant film thickness and, thus, reduce solid-on-solid contact, friction, and wear in hard-on-soft prosthetic hip implant bearings. Specifically, we study the effect of the texture floor profile on the lubricant film thickness using a soft elastohydrodynamic lubrication model. We compute the optimum texture parameters that maximize the lubricant film thickness for different texture floor profiles, as a function of bearing operating conditions. Flat texture floor profiles create thicker lubricant films than sloped or curved texture floor profiles for their respective optimum texture design parameters. We find that the texture feature volume is the most important parameter in terms of maximizing the lubricant film thickness, because a linear relationship exists between the texture feature volume with optimum texture parameters and the corresponding optimum lubricant film thickness, independent of the texture floor profile.

scholarly journals Maximizing the Lubricant Film Thickness Between a Rigid Microtextured and a Smooth Deformable Surface in Relative Motion, Using a Soft Elasto-Hydrodynamic Lubrication Model

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Quentin Allen ◽  
Bart Raeymaekers
Keyword(s):  
Film Thickness ◽  
Hydrodynamic Lubrication ◽  
Elastohydrodynamic Lubrication ◽  
Hydrodynamic Pressure ◽  
Lubricant Film ◽  
Operating Conditions ◽  
Design Parameters ◽  
Lubricant Film Thickness ◽  
Texture Density ◽  
Film Lubrication

Abstract We design a pattern of microtexture features to increase hydrodynamic pressure and lubricant film thickness in a hard-on-soft bearing. We use a soft elastohydrodynamic lubrication model to evaluate the effect of microtexture design parameters and bearing operating conditions on the resulting lubricant film thickness and find that the maximum lubricant film thickness occurs with a texture density between 10% and 40% and texture aspect ratio between 1% and 14%, depending on the bearing load and operating conditions. We show that these results are similar to those of hydrodynamic textured bearing problems because the lubricant film thickness is almost independent of the stiffness of the bearing surfaces in full-film lubrication.

Pitting of Gears and Discs

1974 ◽  
Vol 188 (1) ◽  
pp. 673-682 ◽  
Author(s):  
R. A. Onions ◽  
J. F. Archard
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Surface Finish ◽  
Lubricant Film ◽  
Lubricant Film Thickness ◽  
Probable Reason ◽  
Controlled Conditions

Pitting tests using 127 mm (5 in) centres distance gear rig under controlled conditions are described. These are compared with similar disc tests using the same materials and lubricants. Tests of both types confirm Dawson's conclusion that an important factor influencing pitting life is the ratio of surface roughness to the calculated lubricant film thickness. It has been shown that using a hunting tooth ratio, particularly when associated with a rough harder surface and a surface finish oriented normal to the motion, increases the likelihood of wear. Most importantly, the results show that using disc tests can greatly overestimate the pitting life of gears. These experiments and other evidence from the literature suggest that the most probable reason for these differences between gears and discs lies in dynamic gear loads.

scholarly journals On the Temperature and Lubricant Film Thickness Distribution in EHL Contacts with Arbitrary Entrainment

Lubricants ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 101 ◽  
Author(s):  
Milan Omasta ◽  
Jakub Adam ◽  
Petr Sperka ◽  
Ivan Krupka ◽  
Martin Hartl
Keyword(s):  
Film Thickness ◽  
Thermal Effects ◽  
Film Formation ◽  
Thickness Distribution ◽  
Thickness Measurement ◽  
Lubricant Film ◽  
Operating Conditions ◽  
Lubricant Film Thickness ◽  
Machine Parts ◽  
Film Thickness Measurement

An understanding of mechanisms which are responsible for elastohydrodynamic lubricant film formation under high sliding conditions is necessary to increase durability of machine parts. This work combines thin-film colorimetric interferometry for lubricant film thickness measurement and infrared microscopy for in-depth temperature mapping through the contact. The results describe the effect of operating conditions such as speed, slide-to-roll ratio, ambient temperature, and sliding direction on lubricant film thickness and temperature distribution. Film thickness data shows how much the film shape is sensitive to operating conditions when thermal effects are significant, while the temperature profiles provides an explanation of this behavior.

Ultrasonic Measurement of Rolling Bearing Lubrication Using Piezoelectric Thin Films

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Bruce W. Drinkwater ◽  
Jie Zhang ◽  
Katherine J. Kirk ◽  
Jocelyn Elgoyhen ◽  
Rob S. Dwyer-Joyce
Keyword(s):  
Film Thickness ◽  
High Frequency ◽  
Lubricant Film ◽  
Operating Conditions ◽  
Rolling Element Bearing ◽  
Lubricant Layer ◽  
Lubricant Film Thickness ◽  
Oil Film ◽  
Deep Groove ◽  
Lubricated Contact

This paper describes the measurement of lubricant-film thickness in a rolling element bearing using a piezoelectric thin film transducer to excite and receive ultrasonic signals. High frequency (200 MHz) ultrasound is generated using a piezoelectric aluminum nitride film deposited in the form of a very thin layer onto the outer bearing raceway. This creates a transducer and electrode combination of total thickness of less than 10 μm. In this way the bearing is instrumented with minimal disruption to the housing geometry and the oil-film can be measured noninvasively. The high frequency transducer generates a fine columnar beam of ultrasound that has dimensions less than the typical lubricated contact ellipse. The reflection coefficient from the lubricant-layer is then measured from within the lubricated contact and the oil-film thickness extracted via a quasistatic spring model. The results are described on a deep groove 6016 ball bearing supporting an 80 mm shaft under normal operating conditions. Good agreement is shown over a range of loads and speeds with lubricant-film thickness extracted from elastohydrodynamic lubrication theory.

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