The Stribeck Curve: Experimental Results and Theoretical Prediction

Lu, Xiaobin; Khonsari, M. M.; Gelinck, E.R.M.

doi:10.1115/1.2345406

Cited by 221 publications

(138 citation statements)

References 23 publications

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“…The purpose of this paper is to newly develop an effective method to cleave the principal chain of the thickener molecule in the water-glycol hydraulic fluid by using the processor with the frequency of 20 kHz. The friction coefficient is dependent on the viscosity of the base oil at the constant sliding speed and normal load 8,9) . Another aim is to clarify the relationship between the friction coefficient and viscosity in the lubricant containing the polyethylene glycol molecules cleaved by the ultrasonic process.…”

Section: Introductionmentioning

confidence: 99%

Relationship between Friction Coefficient, Viscosity and Compressibility of Polyethylene Glycol

Hachiya

Nitta

2008

Tribology Online

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An ultrasonic liquid processor with the frequency of 20 kHz was used to cleave a principal chain in a polyethylene glycol molecule. The amount of the lubricant molecules cleaved by the ultrasonic disruption was evaluated by the kinematic viscosity measurement. As the kinematic viscosity in the water-glycol hydraulic fluids of the ethylene glycol solutions containing polyethylene glycols decreased monotonously under the condition that the ultrasound of 20 kHz and 40 W was irradiated for one second every five seconds at either 20 or 40 ºC, the lubricant molecules could be effectively cleaved while reducing the inter-molecular polymerization. The friction coefficients, ultrasonic velocities, densities, and compressibilities in the water-glycol hydraulic fluids were not influenced by the cleavage process of the lubricant molecules. On the other hand, the kinematic viscosities in the undiluted solutions of ethylene glycol and the polyethylene glycols were proportional to their molecular weights, but the friction coefficients and compressibilities in polyethylene glycols hardly depended on their molecular weights except for those in ethylene glycol. These dependences of the frictional coefficients and compressibilities on the molecular weights resulted from a structure of the lubricant oil film formed on the metal surface.

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Section: Introductionmentioning

confidence: 99%

Relationship between Friction Coefficient, Viscosity and Compressibility of Polyethylene Glycol

Hachiya

Nitta

2008

Tribology Online

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“…The method follows the approach of [6,51] where the film formation is modelled independently of asperity contact. The total load supported on the contact, P T is the sum of the loads supported by the asperities, P a and the liquid bridges, P l : …”

Section: Corresponding Author:juanjuan Zhu Paper No: Trib-10-1223 Pmentioning

confidence: 99%

Ultrasonic Measurement for Film Thickness and Solid Contact in Elastohydrodynamic Lubrication

Dwyer-Joyce

Reddyhoff

Zhu

2011

Journal of Tribology

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The reflection of ultrasound can be used to determine oil film thickness in elastohydrodynamic lubricated (EHL) contacts if the opposing surfaces are fully separated by the liquid layer. The proportion of the wave amplitude reflected depends on the stiffness of the liquid layer, which is a function of its bulk modulus and thickness. However, in many practical applications, boundary or mixed film lubrication is a common occurrence as the nominal thickness of the separating film is of a similar order to the height of the surface asperities. The reflection is then dependent on both the liquid contact and solid contact parts and the total interfacial stiffness is the controlling parameter. In this paper an investigation was carried to study the reflection of ultrasonic waves from the lubricated contact between a sliding steel ball and a flat steel disc when substantial solid contact occurs. To interpret the ultrasonic reflection results a mixed regime model for a circular point contact was established. The liquid film stiffness was calculated by using a predicted film thickness and a bulk modulus estimated from published rheological models of lubricants under high pressure. Solid contact stiffness was predicted using a statistical rough surface contact model. Under all operating conditions, the prediction of fluid stiffness was found to be much greater than the solid contact stiffness. The total stiffness predicted by the model showed good agreement with experimental measurements for kinematic cases. The model was used to separate the stiffness contributions from the asperity contact part and lubricant layer part from the experimental data. For a contact pressures ranging from 0.42 to 0.84 GPa and sliding speed from zero to 2 m/s, the film thickness was found to vary from 0.01 to 0.8 µm, and the proportion of the load supported by asperity contact varied from 50% to 0%.

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“…As an additional means of tracking the running-in of the system, four consecutive Stribeck curves [22] are recorded after 1,2,3,4,5,8,11,14,17,20,28,36, and 44 h of mixed lubrication operation, which adds an extra 2.5 h of duration to the entire test procedure. The associated rotational speed profile shown in Fig.…”

Section: Experimental Workflowmentioning

confidence: 99%

An experimental framework for determining wear in porous journal bearings operated in the mixed lubrication regime

Eder¹,

Ielchici²,

Krenn³

et al. 2018

Preprint

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We present an experimental and analysis workflow to characterize the tribological behavior and the wear resistance of porous journal bearing systems operating at high loads and small rotational speeds. Our approach consists of a laser-instrumented tribometer that allows parallel testing of five bearings, an experimental procedure that is optimized for producing sufficient wear during mixed lubrication operation while maintaining realistic operating conditions, as well as several methods to visualize and quantify bearing wear. The simultaneous testing of five bearings prevents outliers from distorting the results and yields a statistical estimation of the performance variations between nominally equivalent tribosystems. We showcase our approach by analyzing the influence of the bearing material and its porosity on mixed-lubrication friction and wear.

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The Stribeck Curve: Experimental Results and Theoretical Prediction

Cited by 221 publications

References 23 publications

Relationship between Friction Coefficient, Viscosity and Compressibility of Polyethylene Glycol

Relationship between Friction Coefficient, Viscosity and Compressibility of Polyethylene Glycol

Ultrasonic Measurement for Film Thickness and Solid Contact in Elastohydrodynamic Lubrication

An experimental framework for determining wear in porous journal bearings operated in the mixed lubrication regime

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