Models for predicting friction coefficient and parameters with influence in elastohydrodynamic lubrication

Morgado, Pilar Lafont; Otero, Javier Echávarri; Sanz, José Luis Muñoz; Lantada, Andrés Díaz; Muñoz-Guijosa, Juan Manuel; Yustos, Héctor Lorenzo; Wiña, María del Pilar Leal; García, Julio Muñoz

doi:10.1243/13506501jet599

Cited by 26 publications

(12 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…It should be stressed again, though, that the non-linear variations of limiting shear stress across the contact due to pressure and temperature variation are neglected in the simplified approach applied here and a more thorough analysis as in the study of Olver and Spikes 13 and Morgado et al 29 needs to be performed.…”

Section: Characterisation Of Viscoelastic Propertiesmentioning

confidence: 99%

Fluid rheology, traction/creep relationships and friction in machine elements with rolling contacts

Poll

Wang

2012

Proceedings of the Institution of Mechanical Engineers, Part J:

View full text Add to dashboard Cite

The correct prediction of shear stresses in lubricants applied to concentrated rolling/sliding contacts has been an issue of intense debate for many years. Traction testers of various kinds such as two-disc roller rigs or ball on disc apparatus have been extensively used in order to obtain experimental data, as well as, more recently, molecular dynamics simulations. Several, partly competing, phenomenological models have been developed to describe the dependence of shear stresses on various parameters. Evidently, the importance lies in the need to predict and reduce friction, or, more accurately, resistance to motion of rolling element bearings in order to increase efficiency of machines and vehicles. Also, it plays a crucial role in design and performance of traction drives. As a prerequisite, experimental data for a wide variety of fluids were obtained from two-disc roller tests with a wide variation of contact pressures, rolling speeds and slide-to-roll ratios. Following earlier investigations, the amount of slip created by the elastic deformation of the discs was separated from the contribution of the fluids and their rheological properties. In accordance with experiments of Jacobson a threshold pressure in the fluid was identified which marks the onset of a nearly linear relationship between a limiting shear stress and pressure. However, this threshold does not appear to be constant but rather declining with decreasing hydrodynamic film thickness respective of rolling speed, while the slope changes to a lesser extent. When measurements were extended far into the mixed lubrication regime close to the limiting case of boundary lubrication, the shear stress/ pressure relationship became quasi-Coulomb with a virtually zero threshold pressure. These results have successfully been used to predict the friction torque of angular contact ball bearings and the traction characteristics in toroidal drives.

show abstract

Section: Characterisation Of Viscoelastic Propertiesmentioning

confidence: 99%

Fluid rheology, traction/creep relationships and friction in machine elements with rolling contacts

Poll

Wang

2012

Proceedings of the Institution of Mechanical Engineers, Part J:

View full text Add to dashboard Cite

show abstract

“…The lubricants used for experimentation were a polyalphaolefin (PAO-6) and a mineral base whose physical properties were measured in the laboratory and are shown in Table 3, exhibiting a temperatureviscosity coefficient of 0.033 K −1 . The parameters n and G of Carreau's model and the thermal conductivity at 80 • C are approximately [22]: n = 0.81, G = 0.1 MPa, and K l = 0.15 W/m • C for the PAO-6; and n = 0.50, G = 1.0 MPa, and K l = 0.12 W/m • C for the mineral base.…”

Section: Experimentationmentioning

confidence: 94%

“…By integrating the shear stress in the contact area and dividing by the load, the traction (or friction) coefficient (μ) is obtained. The integration can be performed analytically when the Newtonian shear stress is substantially greater than the parameter G in most of the contact area, with the following result being given [22]…”

Section: Traction Coefficientmentioning

confidence: 99%

“…The average increase in the temperature of the lubricant due to internal heating of the film ( T l ) is obtained from the heat balance equation in the lubricant [31] T l = μW uh c 8πa 2 K l (14) The difference between the inlet temperature (T in ) and the lubricant bath temperature (T b ) can be estimated by comparing the expressions for thermal and isothermal film thicknesses (equations ( 8) and ( 9)), since the viscosity-temperature relationship is known. For this estimation the equation ( 15) can be used, where the unknown is the inlet temperature [22] […”

Section: Temperaturementioning

confidence: 99%

See 1 more Smart Citation

Analytical model for predicting the friction coefficient in point contacts with thermal elastohydrodynamic lubrication

Otero

Morgado

Tanarro

et al. 2011

Proceedings of the Institution of Mechanical Engineers, Part J:

Self Cite

View full text Add to dashboard Cite

This article presents analytical friction prediction models applicable to lubricants in point contacts under thermal elastohydrodynamic lubrication (TEHL). The types of models used consider the heat generated and its penetration into the bulk of the contacting solids. Therefore, the increase in temperature is determined, which causes important variations in the operating conditions. The article sets out the hypotheses assumed, the theoretical calculation procedures and the ensuing equations for determining the friction coefficient under TEHL. An experimental stage is performed on a mini-traction-machine, which allows the measurement of friction coefficient in ball–disc contacts under a wide range of control parameters involved in TEHL, such as lubricant bath temperature, load, average velocity, slide-to-roll ratio, and contacting materials. The experimental results for different lubricants are compared to those given by the models, and show the proposed models to be accurate for predicting the friction coefficient.

show abstract

“…In a previous study, the correlation between the traction coefficient and pressure-viscosity coefficient of the lubricant was reported [2][3][4]. Furthermore, numerical simulation [5,6] and a predictive method for the power transmission of a toroidal CVT [7] have been investigated.…”

Section: Introductionmentioning

confidence: 99%

Effect of Functional Groups of Polyglycol Oils on Their Lubrication Properties

et al. 2021

View full text Add to dashboard Cite

The effect of molecular structure on the traction properties of polyglycol oils was investigated using a traction tester, and in-situ observation of the oil film was performed with a micro-Fourier transform infrared spectrometer under elastohydrodynamic lubrication conditions. The sample oils used were polypropylene glycol (PPG) diol, PPG triol, PPG dimethyl ether, PPG diester, PPG diamine, PPG triamine, and poly-α-olefin. The traction coefficient and oil film thickness of the sample oils were sensitive to the functional group at the terminal of the molecule. The sample oil containing polar functional group is larger in oil film thickness and traction coefficient than non-polar hydrocarbon oil, poly-α-olefin. These results suggest that the hydrogen bonding of functional groups was strengthened by high pressure in the Hertzian contact region. Moreover, the effect of water in the sample oils on the traction behavior was discussed. Water was dissolved into the sample oils from the atmosphere during the lubrication test, and it is implied that water in PPG diamine affect the traction coefficient.

show abstract

Models for predicting friction coefficient and parameters with influence in elastohydrodynamic lubrication

Cited by 26 publications

References 19 publications

Fluid rheology, traction/creep relationships and friction in machine elements with rolling contacts

Fluid rheology, traction/creep relationships and friction in machine elements with rolling contacts

Analytical model for predicting the friction coefficient in point contacts with thermal elastohydrodynamic lubrication

Effect of Functional Groups of Polyglycol Oils on Their Lubrication Properties

Contact Info

Product

Resources

About