Piezoviscous Effects in Nonconformal Contacts Lubricated Hydrodynamically

Jeng, Yeau-Ren; Hamrock, B. J.; Brewe, D. E.

doi:10.1080/05698198708981779

Cited by 10 publications

(7 citation statements)

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“…This occurs rarely in practical applications but it has been suggested that it may be present in roller end-guide flanges in moderately highly loaded cylindrical tapered roller bearings [10] Considerable numerical modelling work has been carried out to solve combinations of the Reynolds, elastic deformation and piezoviscosity equations and thus develop regression equations to predict both central and minimum film thickness in all of the above four hydrodynamic regimes [4][5][6][7]. For the circular point contact of interest to the current study, …”

Section: Introductionmentioning

confidence: 99%

Elastohydrodynamic film thickness of soft EHL contacts using optical interferometry

Marx

Guegan

Spikes

2016

Tribology International

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Robust, chromium, semi-reflective coatings have been applied to transparent polymethylmethacrylate and polyurethane discs and this has enabled conventional, normal incidence optical interferometry to be used to measure lubricant film thickness in soft EHL conditions for the first time. High quality interferograms comparable to those obtained from coated glass discs are obtained. Measured film thickness has been compared with existing soft EHL film thickness equations obtained using computer modelling and revised central and minimum film thickness equations have been proposed. These film thickness measurements and measurement technique have applicability to our understanding of the performance and design of lubricated gears and bearings manufactured from polymeric materials.

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Section: Introductionmentioning

confidence: 99%

Elastohydrodynamic film thickness of soft EHL contacts using optical interferometry

Marx

Guegan

Spikes

2016

Tribology International

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“…In a completely different way, Venner [28] and Chevalier [29] later obtained very close asymptote equations for both central and minimum film thicknesses from numerical EHD solvers. Finally, Jeng et al [33] published a numerical expression to describe the PR regime. All the equations mentioned can be written as follows for fully flooded circular lubricated point contacts: one note that the Venner and Chevalier equations for It was easy to check by eye from the interferograms that fully flooded conditions applied during tests conducted in the EHD regime and in the transition from EHL towards hydrodynamic lubrication.…”

Section: Resultsmentioning

confidence: 99%

An exploration of the elastohydrodynamic— hydrodynamic transition through film thickness measurements in rolling point contacts

Dalmaz

Chaomleffel

Vergne

2009

Proceedings of the Institution of Mechanical Engineers, Part J:

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The numerical solution of the elastohydrodynamic lubrication (EHL) problem is often presented in charts where dimensionless parameters and asymptotic relationships are used. Among them, the so-called isoviscous rigid asymptote is especially interesting because it defines the transition between elastohydrodynamic and hydrodynamic regimes, or between piezoviscous-elastic and isoviscous-rigid problems, respectively. In other respects, the combination of moderate contact pressures (i.e. moderate piezoviscosity, low normal load, and/or large radii of curvature) and high viscosity and speeds (i.e. high hydrodynamic effect) is quite often found in working mechanisms, for instance in most flange contacts in roller bearings. Surprisingly, only a few papers have analysed and discussed these operating conditions.Based on experimental results obtained in the range of the Moes parameters 15 < L < 50 and 2 < M < 160 for pure rolling circular point contacts, the aim of this work is first to show how film thickness distributions are affected when the piezoviscous elastic to isoviscous rigid transition is approached. In this context, the relative values taken by the central and minimum film thicknesses will be particularly studied. The second objective is to compare our results with those predicted by elastohydrodynamic and hydrodynamic solutions for non-conformal contacts found in the literature. Finally, the exploration of mild EHL is dealt with and a former publication in which electrohydrodynamic very thin films and highly loaded thick film regimes were studied is completed.physical meaning of most of the EHL representations that are still in current use. The latter can be schematically classified into two categories according to the number of dimensionless parameters that have been kept to describe the EHL regimes. Dowson and Higginson [2] proposed the four classical dimensionless groups H D , U , G, and W . Greenwood [3], Johnson [4], and Hooke [5], using three groups, and Hamrock and Dowson [6], using four dimensionless groups, proposed different diagrams in which they compiled the occurrence of various lubrication regimes in different ways. On the other hand, the Dutch approach, mainly inspired and developed in Delft University since 1950 by Blok [7], proved that only three dimensionless groups are required for a full description of the whole EHL field. As mentioned by Higginson [1], Theyse [8] published a study in which he JET550

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“…II F), the magnitude of _ c zy ( _ c xy . 22 We summarize the modified viscosity approach as a system of equations comprising of a single non-linear Reynolds equation and an expression for the modified viscosity, @ @x h 3 12…”

Section: Modified Viscosity Approachmentioning

confidence: 99%

“…1 The second major effect due to the pressure is piezoviscosity, which is the possibility of the lubricant viscosity to increase due to the large pressure. 3 The intertwining of the polymer molecules as they are brought closer to each other due to the pressure leads to an increase in the flow resistance, which results in a higher viscosity. 4 This relationship is not linear and is generally explained by using empirical relations obtained from experimental data.…”

Section: Introductionmentioning

confidence: 99%

A modified viscosity approach for shear thinning lubricants

Ahmed

Biancofiore

2022

Physics of Fluids

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Lubrication is essential to minimize wear and friction between contacting surfaces in relative motion. Oil based lubricants are often enhanced via polymer additives to minimize self-degradation due to the shear thinning effect. Therefore, an accurate estimate of the load carrying capacity of the thin lubricating film requires careful modeling of shear thinning. Available models such as the generalized Reynolds equation (GR) and the approximate shear distribution have drawbacks such as large computational time and poor accuracy, respectively. In this work, we present a new approach, i.e., the modified viscosity (MV) model, based on calculating the strain rate only in one point along the vertical direction. We investigate, for both MV and GR, the load, the maximum pressure, and the computational time for (i) sliding (non-cavitating) contacts, (ii) cavitating, and (iii) squeezing contacts. We observe that the computational time is reduced (i) considerably for non-cavitating sliding and rolling contacts and (ii) by several orders of magnitudes for cavitating and squeezing contacts. Furthermore, the accuracy of MV is comparable with the GR model within an appreciable range of bearing numbers. Finally, for each type of boundary motion, we have determined the optimal vertical location to calculate the shear strain rate for MV; while this optimal value is close to half the height of the contact for sliding configurations, for rolling dominated and squeezing contacts it is around one quarter (or three quarter) of their height. We finally provide an analysis to a priori estimate the optimal location of the strain rate.

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Piezoviscous Effects in Nonconformal Contacts Lubricated Hydrodynamically

Cited by 10 publications

References 10 publications

Elastohydrodynamic film thickness of soft EHL contacts using optical interferometry

Elastohydrodynamic film thickness of soft EHL contacts using optical interferometry

An exploration of the elastohydrodynamic— hydrodynamic transition through film thickness measurements in rolling point contacts

A modified viscosity approach for shear thinning lubricants

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