Viscoelastic Effects in MIL-L-7808-Type Lubricant, Part I: Analytical Formulation

Gupta, Pradeep K.; Cheng, H. S.; Zhu, Dong; Forster, Nelson H.; Schrand, J. B.

doi:10.1080/10402009208982117

Cited by 120 publications

(71 citation statements)

References 5 publications

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“…Figures 8 and 9 display the specific film thickness calculated for the tests performed for TBB and RTB, respectively. The centre film thickness in the rollerraceway contact of the RTB was determined using the Dowson and Higginson [25] equation for rectangular contacts and the centre film thickness in the ballraceway contact of the BTB was determined using the Hamrock and Dowson [26] equation for elliptical contacts, both corrected with the thermal reduction factor due to inlet shear heating proposed by Gupta et al [27]. The first fact to be noticed is that TBB tests were performed under boundary lubrication regime, while for the RTB half of the tests were performed in boundary and half in mixed lubrication regime.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of bearing, gears and gearboxes performance with different wind turbine gear oils

2015

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Abstract:The oil viscosity specification for wind turbine gear oils is ISO VG 320, although there are quite different viscosity indexes oils for that viscosity specification. This work evaluates the behaviour of different base oil formulations, since polyalphaolefin (PAO), mineral, ester and polyalkeleneglycol (PAG) that withstand quite different viscosity indexes. The oils evaluation was done in rolling bearing tests and gear tests. Their behaviour was compared for operating conditions in the range observable in a wind turbine gearbox.The experimental results showed considerable differences between the different oils and it was observed that depending on the contact type the relative behaviour of the lubricants would change, i.e., the best lubricant for the rolling bearing would not imply the best result on the gear tests.The gear geometry is also very important toward the transmission efficiency, once using a low loss gear concept a decrease of up to 25% in torque loss could be achieved.Numerical models were implemented with the purpose of performing a better simulation of the mechanical system and also to obtain the friction coefficient promoted by the tested oils.

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Section: Discussionmentioning

confidence: 99%

Evaluation of bearing, gears and gearboxes performance with different wind turbine gear oils

2015

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“…(16) assumes pure rolling conditions at the inlet conjunction. It is known that increasing SRR leads to increased inlet temperature rise [39]. However, given the conditions and the properties of the lubricants used in this study, the difference between the thermal reduction coefficient (Eq.…”

Section: Inlet Zone Thermal Analysismentioning

confidence: 99%

“…When the speed of entraining motion exceeds 1 m=s, excluding the effects of ISH and starvation tends to a significant overestimation of the central contact oil film thickness. Applying the correction factor of Gupta et al [39] without the inclusion of the starvation phenomena also tends to overestimate the central oil film thickness. Figure 6 shows this trend.…”

Section: Film Thicknessmentioning

confidence: 99%

“…However, given the conditions and the properties of the lubricants used in this study, the difference between the thermal reduction coefficient (Eq. 20) under pure rolling and that with 50 % SRR is merely 8 % [39]. Therefore, it is reasonable to apply the ISH described here to higher SRR values, representing the conditions encountered in MTM testing without incurring any significant error.…”

Section: Inlet Zone Thermal Analysismentioning

confidence: 99%

“…6.1). In the case of ISH, a ''thermal reduction coefficient'' can be used to adjust the predicted lubricant film thickness [39]:…”

Section: Inlet Zone Thermal Analysismentioning

confidence: 99%

See 2 more Smart Citations

An Analytical Approach for Prediction of Elastohydrodynamic Friction with Inlet Shear Heating and Starvation

et al. 2016

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An analytical friction model is presented, predicting the coefficient of friction in elastohydrodynamic (EHD) contacts. Three fully formulated SAE 75W-90 axle lubricants are examined. The effect of inlet shear heating (ISH) and starvation is accounted for in the developed friction model. The film thickness and the predicted friction are compared with experimental measurements obtained through optical interferometry and use of a mini traction machine. The results indicate the significant contribution of ISH and starvation on both the film thickness and coefficient of friction. A strong interaction between those two phenomena is also demonstrated, along with their individual and combined contribution on the EHD friction.

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Base fluid parameters for elastohydrodynamic lubrication and friction calculations and their influence on lubrication capability

Larsson¹,

Kassfeldt²,

Byheden³

et al. 2001

J of Synthetic Lubrication

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Viscoelastic Effects in MIL-L-7808-Type Lubricant, Part I: Analytical Formulation

Cited by 120 publications

References 5 publications

Evaluation of bearing, gears and gearboxes performance with different wind turbine gear oils

Evaluation of bearing, gears and gearboxes performance with different wind turbine gear oils

An Analytical Approach for Prediction of Elastohydrodynamic Friction with Inlet Shear Heating and Starvation

Base fluid parameters for elastohydrodynamic lubrication and friction calculations and their influence on lubrication capability

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