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.

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.

Pressure Distribution Within EHD Point Contacts Based on Measured Film Thickness

Tribology ◽  
2006 ◽  
Author(s):  
Radek Poliscuk ◽  
Michal Vaverka ◽  
Martin Vrbka ◽  
Ivan Krupka ◽  
Martin Hartl
Keyword(s):  
Film Thickness ◽  
Numerical Solution ◽  
Pressure Distribution ◽  
Elastic Deformation ◽  
Contact Fatigue ◽  
Lubricant Film ◽  
Rolling Contact ◽  
Lubricant Film Thickness ◽  
Machine Elements ◽  
Lubricated Contact

Surface topography significantly influences the behavior of lubricated contacts between highly loaded machine elements. Most oil- or grease- lubricated machine elements such as gears, rolling bearings, cams and traction drives operate in mixed lubrication conditions and the lubricant film thickness is directly related to the main practical performance parameters such as function, wear, contact fatigue and scuffing. For determination wear and especially contact fatigue, the values and distribution of the pressure in rolling contact are required. The theoretical studies usually involve the numerical solution of pressure and film thickness in the contact, using some physical mathematical model built around the Reynolds equation to describe the flow and the theory of elastic deformation of semi-infinite bodies. Such calculations can be extremely time consuming, especially when lubricant films are very thin and/or contact load very high. This study is aimed at obtaining pressure distribution within lubricated contact from measured film thickness. Lubricant film thickness distribution within the whole concentrated contact is evaluated from chromatic interferograms by thin film colorimetric interferometry. Consequently, an elastic deformation is separated from the film thickness, geometry and mutual approach of the surfaces. Calculation of the pressure distribution is based on inverse elasticity theory. EHD lubricated contact with smooth surfaces of solids was first investigated. Calculated pressure, distributions were compared with data obtained from full numerical solution to check the accuracy. The approach was also applied to surfaces with dents and their influence on distribution of pressure in lubricant film.

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.

Study of Scale Effect in a Starved Elastohydrodynamically Lubricated Contact

2016 ◽  
Vol 821 ◽  
pp. 138-143
Author(s):  
Petr Svoboda ◽  
David Kostal ◽  
Ivan Křupka ◽  
Martin Hartl
Keyword(s):  
Film Thickness ◽  
Scale Effect ◽  
Thickness Measurement ◽  
Lubricant Film ◽  
Scale Model ◽  
Lubricant Film Thickness ◽  
Film Distribution ◽  
Multiple Contacts ◽  
Optical Test ◽  
Lubricated Contact

The article describes an experimental investigation of scale effect in a starved elastohydrodynamically lubricated contact on lubricant film thickness. Lubricant film thickness and its distribution is one of the most important parameters determining the performance and life of machine parts. Current experimental and numerical studies are mostly connected with oil lubrication. However, greases are used in more than 80 % of all rolling bearings where the starvation phenomenon occurs most frequently. The aim of this work is to compare two approaches to measuring film thickness of different greases. The use of multiple contacts optical test rig based on thin film colorimetric interferometry for film thickness measurement has enables to obtain film thickness of starved contact and the film distribution. The experimental observation of full-scale model of bearing will help to understand better the behavior of real bearing. The evaluation of the experiment was made by chromatic interferometry. This method is used to measure thin lubrication films.

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.

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.

Lubricant Film Thickness in Rough Surface, Mixed Elastohydrodynamic Contact

1999 ◽  
Vol 122 (1) ◽  
pp. 65-76 ◽  
Author(s):  
G. Guangteng ◽  
P. M. Cann ◽  
A. V. Olver ◽  
H. A. Spikes
Keyword(s):  
Film Thickness ◽  
Rough Surface ◽  
Smooth Surface ◽  
Rolling Speed ◽  
Lubricant Film ◽  
Operating Conditions ◽  
Mapping Technique ◽  
Lubricant Film Thickness ◽  
Model Surface ◽  
Surface Features

A spacer layer imaging method has been employed to map lubricant film thickness in very thin film, rough surface, rolling elastohydrodynamic (EHD) contacts. A series of model roughnesses have been produced by depositing tiny ridges and bumps on a steel ball surface and the influence of these features on film thickness has been investigated at a range of rolling speeds. It has been shown that all the model surface features studied form speed-dependent, micro-EHD lubricating films, but the detailed shape and thickness of these films depends upon the geometry of the feature and the rolling speed. All model surface features also produce a net increase in mean film thickness, compared to the smooth surface, under operating conditions where the film thickness is less than the out-of-contact height of the surface feature studied. For a real, random, rough surface, however, mean film thickness is less than the smooth surface case. The film thickness mapping technique has also been used to measure the effective roughness of surfaces in lubricated contact. This shows that surfaces based on 2-D array of tiny circular bumps become rougher as the rolling speed and thus film thickness increases. However, real, rough surfaces appear to show a decrease of in-contact roughness with increasing rolling speed. [S0742-4787(00)01001-8]

A Thermal Reynolds Equation and Its Application in the Analysis of Plasto-Hydrodynamic Inlet Zones

1974 ◽  
Vol 96 (4) ◽  
pp. 572-577 ◽  
Author(s):  
W. R. D. Wilson ◽  
S. M. Mahdavian
Keyword(s):  
Energy Dissipation ◽  
Film Thickness ◽  
Reynolds Equation ◽  
Wire Drawing ◽  
Lubricant Film ◽  
Pressure Gradients ◽  
Lubricant Film Thickness ◽  
Strip Rolling ◽  
Deformation Processes ◽  
Lubricated Contact

An equation which is equivalent to the steady, one-dimensional incompressible Reynolds equation but which takes account of viscosity variations across the lubricant film thickness due to energy dissipation within the film is developed. It indicates that the pressure gradients developed in a lubricated contact are reduced by the influence of energy dissipation. The use of the equation is illustrated by applying it in the analysis of the inlet zones of continuous deformation processes such as strip rolling and strip and wire drawing. The analysis indicates that thermal effects play an important role in deciding the lubricant film thickness in such contacts.

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