Interferometry-based measurements of oil-film thickness

Marklund, Olov; Gustafsson, Lennart

doi:10.1243/1350650011543510

Cited by 18 publications

(12 citation statements)

References 21 publications

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“…Therefore, the friction coefficient is then calculated from the normal force and the friction force. The central film thickness is obtained by optical interferometry through the wavelength of the light returned from the central plateau of the contact [40]. The glass disc can be tested up to approximately 0.7 GPa of maximum Hertz pressure and the ball specimen presents a high-grade surface finish.…”

Section: Film Thickness Measurementsmentioning

confidence: 99%

Tribological Behavior of Nanolubricants Based on Coated Magnetic Nanoparticles and Trimethylolpropane Trioleate Base Oil

et al. 2020

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The main task of this work is to study the tribological performance of nanolubricants formed by trimethylolpropane trioleate (TMPTO) base oil with magnetic nanoparticles coated with oleic acid: Fe3O4 of two sizes 6.3 nm and 10 nm, and Nd alloy compound of 19 nm. Coated nanoparticles (NPs) were synthesized via chemical co-precipitation or thermal decomposition by adsorption with oleic acid in the same step. Three nanodispersions of TMPTO of 0.015 wt% of each NP were prepared, which were stable for at least 11 months. Two different types of tribological tests were carried out: pure sliding conditions and rolling conditions (5% slide to roll ratio). With the aim of analyzing the wear by means of the wear scar diameter (WSD), the wear track depth and the volume of the wear track produced after the first type of the tribological tests, a 3D optical profiler was used. The best tribological performance was found for the Nd alloy compound nanodispersion, with reductions of 29% and 67% in friction and WSD, respectively, in comparison with TMPTO. On the other hand, rolling conditions tests were utilized to study friction and film thickness of nanolubricants, determining that Fe3O4 (6.3 nm) nanolubricant reduces friction in comparison to TMPTO.

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Section: Film Thickness Measurementsmentioning

confidence: 99%

Tribological Behavior of Nanolubricants Based on Coated Magnetic Nanoparticles and Trimethylolpropane Trioleate Base Oil

et al. 2020

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“…The EHD film thickness was measured by the optical interferometry technique, described in detail by these and other authors in various publications [34][35][36]. The schematic of the experimental arrangement is shown in Fig.…”

Section: Experimental Setup and Working Conditionsmentioning

confidence: 99%

Elastohydrodynamic Films Under Periodic Load Variation: An Experimental and Theoretical Approach

Glovnea

Zhang

2018

Tribol Lett

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The elastohydrodynamic lubrication regime occurs in systems where large elastic deformations, the hydrodynamic action of a converging wedge and eventually large variation of viscosity of the fluid combine to determine the formation of a continuous fluid film that separates the solid surfaces. Experimental and theoretical works, over the past few decades, have elucidated the role of various working and material parameters on the lubricant film thickness which plays a crucial role in protecting the solid surfaces from direct contact and ultimately from failure. These mechanisms are well understood for steady-state conditions; however, elastohydrodynamic contacts most often experience transient conditions, including variation of geometry, velocity of surfaces or load. In this case, the mechanisms of film formation are more complex involving film squeeze in addition to the mechanisms mentioned above. Experimental and theoretical modelling of transient phenomena in elastohydrodynamic lubrication include sudden variation of entrainment speed or load and changing geometry. No systematic experimental study on the effect of harmonic load vibration upon the elastohydrodynamic films has been published before. In order to cover this gap, this paper presents the results of an experimental study and of a simple theoretical approach on the behaviour of the elastohydrodynamic film thickness under harmonic variation of load.

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“…Full details of methods on how to use HSV and the H channel in particular for film thickness measurements can be found in [10][11][12][13]. Here only the main aspects are reported for understanding the methodologies used in the programme specifically realised for fast processing of image series from experiments under transient conditions.…”

Section: Basic Aspects Of Optical Interferometry Applied To Ehl Contactsmentioning

confidence: 99%

“…Since multidimensional phase unwrapping is a task that occurs in various applications, such as magnetic resonance imaging or radar interferometry, various rather complex algorithms have been developed for it in the past. For example, the algorithm presented in [14] had received par-ticular attention and was an important basis for the further developments conducted in [10,12]. Several versions of the algorithms found in the literature have been implemented in the Matlab environment and tested with interference images obtained with the experimental apparatus described in the following (e.g., [15]).…”

Section: Basic Aspects Of Optical Interferometry Applied To Ehl Contactsmentioning

confidence: 99%

Film Thickness Analysis for EHL Contacts under Steady‐State and Transient Conditions by Automatic Digital Image Processing

Ciulli¹,

Draexl²,

Stadler³

2007

Advances in Tribology

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The knowledge of the film thickness values is very important in lubricated contacts to verify the lubrication conditions. Optical interferometry is one of the most used methodologies for film thickness and shape determination of Elastohydrodynamic-lubricated contacts. An image processing programme has been developed for the analysis of white light interferograms. The programme, based on the analysis of the hue channel, has been developed in order to process big amounts of images, as often generated under transient conditions. The measurement range is currently limited to a maximum film thickness of 0.7 m. The programme has been used for analysing several images recorded in tests carried out with a ball on disc contact under steady-state as well as transient conditions for different velocities and slide-to-roll ratios. Under transient conditions, the entraining velocity is varied with a sinusoidal law for two different frequencies. The results obtained evidenced an asymmetric reduction of the film thickness when increasing the percentage of sliding, both for stationary and transient conditions. Under transient conditions with increasing test frequency, film thickness loops of increasing amplitude have been found that reduce their amplitude more when the ball is running faster than the disc. Squeeze and thermal effects can explain the results obtained.

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Interferometry-based measurements of oil-film thickness

Cited by 18 publications

References 21 publications

Tribological Behavior of Nanolubricants Based on Coated Magnetic Nanoparticles and Trimethylolpropane Trioleate Base Oil

Tribological Behavior of Nanolubricants Based on Coated Magnetic Nanoparticles and Trimethylolpropane Trioleate Base Oil

Elastohydrodynamic Films Under Periodic Load Variation: An Experimental and Theoretical Approach

Film Thickness Analysis for EHL Contacts under Steady‐State and Transient Conditions by Automatic Digital Image Processing

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