A coupled finite-volume CFD solver for two-dimensional elasto-hydrodynamic lubrication problems with particular application to rolling element bearings

Hajishafiee, Alireza; Kadiric, Amir; Ioannides, Stathis; Dini, Daniele

doi:10.1016/j.triboint.2016.12.046

Cited by 67 publications

(41 citation statements)

References 40 publications

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“…Accurate prediction of temperatures in lubricated rolling-sliding EHL contacts is not straight forward. CFD methods can be used to obtain complete temperature distribution [29] but given the computational complexities involved, this approach is only really feasible for single contacts and not practical in the case of real components, particularly when bulk temperatures are of interest. Given these difficulties, various approximations are commonly used to provide rough estimates in affected applications, notably in gears [30].…”

Section: Isolating the Influence Of Slide-roll Ratio On Micropitting mentioning

confidence: 99%

The Influence of Slide–Roll Ratio on the Extent of Micropitting Damage in Rolling–Sliding Contacts Pertinent to Gear Applications

Rycerz

Kadiric

2019

Tribol Lett

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Micropitting is a type of surface damage that occurs in rolling-sliding contacts operating under thin oil film, mixed lubrication conditions, such as those formed between meshing gear teeth. Like the more widely studied pitting damage, micropitting is caused by the general mechanism of rolling contact fatigue but, in contrast to pitting, it manifests itself through the formation of micropits on the local, roughness asperity level. Despite the fact that micropitting is increasingly becoming a major mode of gear failure, the relevant mechanisms are poorly understood and there are currently no established design criteria to assess the risk of micropitting occurrence in gears or other applications. This paper provides new understanding of the tribological mechanisms that drive the occurrence of micropitting damage and serves to inform the ongoing discussions on suitable design criteria in relation to the influence of contact slide-roll ratio (SRR) on micropitting. A triple-disc rolling contact fatigue rig is used to experimentally study the influence of the magnitude and direction of SRR on the progression of micropitting damage in samples made of case-carburised gear steel. The test conditions are closely controlled to isolate the influence of the variable of interest. In particular, any variation in bulk heating at different SRRs is eliminated so that tests are conducted at the same film thickness for all SRRs. The results show that increasing the magnitude of SRR increases the level of micropitting damage and that negative SRRs (i.e. the component where damage is being accumulated is slower) produce more micropitting than the equivalent positive SRRs. Measurements of elastohydrodynamic film thickness show that in the absence of bulk heating, increasing SRR does not cause a reduction in EHL film thickness and therefore this cannot be the reason for the increased micropitting at higher SRRs. Instead, we show that the main mechanism by which increase in SRR promotes micropitting is by increasing the number of micro-contact stress cycles experienced by roughness asperities during their passage through the rolling-sliding contact. Therefore, the asperity stress history should form the basis of any potential design criterion against micropitting.

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Section: Isolating the Influence Of Slide-roll Ratio On Micropitting mentioning

confidence: 99%

The Influence of Slide–Roll Ratio on the Extent of Micropitting Damage in Rolling–Sliding Contacts Pertinent to Gear Applications

Rycerz

Kadiric

2019

Tribol Lett

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“…A comparison against friction measurements was also presented showing good correlation for the friction coefficient. Feldermann et al [7] also published an CFD approach validated against a Reynolds solver while Hajishafiee et al [8] developed a CFD approached for fluid and FEM for solid in the OpenFOAM package. They also validated this against Hartinger et al's previously published CFDdata [4] and found good agreement for thermal and isothermal test cases.…”

Section: Introductionmentioning

confidence: 99%

CFD modeling compared to temperature and friction measurements of an EHL line contact

Hartinger

Reddyhoff

2018

Tribology International

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In this paper, predictions from CFD modeling are compared against measurements of surface temperatures and friction for an EHL line contact lubricated with the fluid Santotrac 50. Two slide-to-roll-ratios (SRR), 50% and 100%, and entrainment velocities ranging from 0.211 to 1.13 m/s are considered. Very good agreement is shown for the 50% SRR cases, with only a 3% deviation in friction coefficient values. At 100% SRR, the deviation in friction increases to 3-7% which is attributed to deficiencies in the modeling approach with regard to shearthinning. The temperature profiles agree reasonably well at 50% SRR and show larger deviations at 100% SRR. For all cases, the formation of a shear-band in the center of the fluid film is predicted. This is very pronounced for 100% SRR, although likely to be over-estimated by this CFD-approach. The data presented here serve as a basis from which further refinements in the modeling and measurements shown can be made.

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“…They have also used the Ree-Eyring model and found that their results are in good correlation with previously published CFD results with pressures of up to approximately 0.6 GPa. In 2017, Hajishafiee et al [14] performed a CFD analysis of thermal EHL and reached higher pressure levels over 3 GPa. They computed viscosity by using the model combination of Houpert and Ree-Eyring.…”

Section: Introductionmentioning

confidence: 99%

A Computational Fluid Dynamics Study on Shearing Mechanisms in Thermal Elastohydrodynamic Line Contacts

et al. 2019

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A computational fluid dynamics (CFD) model of the thermal elastohydrodynamically lubricated (EHL) line contact problem has been developed for the purpose of exploring the physical processes that occur inside a thin EHL film subjected to shearing motion. The Navier-Stokes equations are solved by using the finite volume method (FVM) in a commercial CFD software, ANSYS Fluent. A set of user-defined functions (UDF) are used for computing viscosity, density, heat source, temperature of moving surfaces and elastic deformation of the top roller according to well-established equations commonly used in the EHL theory. The cavitation problem is solved by taking into account multiphase mixture flow. The model combinations of Houpert and Ree-Eyring and of Tait and Carreau were used for modeling the non-Newtonian behavior of Squalane and the results were compared. Both rheological models suggest the existence of shear-band and plug-flow at high fluid pressure. Due to the differences in viscosity at GPa-level pressure, the chosen model has substantial influence on the computed shear stress and temperature distributions in the high-pressure region. This shows the importance of using correct rheology information in the whole range of pressure, temperature, and shear strain rate.

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A coupled finite-volume CFD solver for two-dimensional elasto-hydrodynamic lubrication problems with particular application to rolling element bearings

Cited by 67 publications

References 40 publications

The Influence of Slide–Roll Ratio on the Extent of Micropitting Damage in Rolling–Sliding Contacts Pertinent to Gear Applications

The Influence of Slide–Roll Ratio on the Extent of Micropitting Damage in Rolling–Sliding Contacts Pertinent to Gear Applications

CFD modeling compared to temperature and friction measurements of an EHL line contact

A Computational Fluid Dynamics Study on Shearing Mechanisms in Thermal Elastohydrodynamic Line Contacts

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