The Behavior of Plain Hydrodynamic Journal Bearings During Starting and Stopping

Mokhtar, Mohamed; Howarth, R. B.; Davies, P. B.

doi:10.1080/05698197708982832

Cited by 35 publications

(27 citation statements)

References 4 publications

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“…With increasing sliding speed, the effects of surface roughness on the transient characteristics of hydrodynamic cylindrical bearings become more prominent. In further simulation studies [21,25], it was shown that the time duration of asperity contact during startup can be reduced by lowering surface roughness, which is in agreement to experimental observations [26].…”

Section: Introductionsupporting

confidence: 85%

“…10(b). The slight increase of CoF can be explained by the negligible asperity interaction during stopping, which was also observed by Mokhtar et al [26].…”

Section: Comparison Of Simulated and Experimental Frictional Lossessupporting

confidence: 75%

“…After that period, a slight decrease towards 0.16 and a shift of the maximum value to higher rotational speeds can be observed. This can be explained by the experimental observations by Mokhtar et al, where the shaft initially rotated along the bearing wall before the build-up of hydrodynamic pressure led to sliding motion [26]. During stopping, the CoF of 0.2 continuously decreases after a few hundred start-stop cycles, which can be explained by the improved build-up of hydrodynamic pressure and reduced asperity interaction between worn-in surfaces [20,21].…”

Section: Comparison Of Simulated and Experimental Frictional Lossesmentioning

confidence: 89%

“…Mokhtar et al even observed that asperity interaction was only present after the shaft rotation fully ceased. Until then, the surfaces were separated by the lubricant [26].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Numerical prediction of the frictional losses in sliding bearings during start-stop operation

2020

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With the increased use of automotive engine start-stop systems, the numerical prediction and reduction of frictional losses in sliding bearings during starting and stopping procedures has become an important issue. In engineering practice, numerical simulations of sliding bearings in automotive engines are performed with statistical asperity contact models with empirical values for the necessary surface parameters. The aim of this study is to elucidate the applicability of these approaches for the prediction of friction in sliding bearings subjected to start-stop operation. For this purpose, the friction performance of sliding bearings was investigated in experiments on a test rig and in transient mixed elasto-hydrodynamic simulations in a multi-body simulation environment (mixed-EHL/MBS). In mixed-EHL/MBS, the extended Reynold’s equation with flow factors according to Patir and Cheng has been combined on the one hand with the statistical asperity contact model according to Greenwood and Tripp and on the other hand with the deterministic asperity contact model according to Herbst. The detailed comparison of simulation and experimental results clarifies that the application of statistical asperity contact models with empirical values of the necessary inputs leads to large deviations between experiment and simulation. The actual distribution and position of surface roughness, as used in deterministic contact modelling, is necessary for a reliable prediction of the frictional losses in sliding bearings during start-stop operation.

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Section: Introductionsupporting

confidence: 85%

“…10(b). The slight increase of CoF can be explained by the negligible asperity interaction during stopping, which was also observed by Mokhtar et al [26].…”

Section: Comparison Of Simulated and Experimental Frictional Lossessupporting

confidence: 75%

Section: Comparison Of Simulated and Experimental Frictional Lossesmentioning

confidence: 89%

“…Mokhtar et al even observed that asperity interaction was only present after the shaft rotation fully ceased. Until then, the surfaces were separated by the lubricant [26].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Numerical prediction of the frictional losses in sliding bearings during start-stop operation

2020

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“…In regard to mixed lubrication, Beheshti and Khonsari [21] focused on an elastohydrodynamic lubrication (EHL) line contact and presented an engineering approach for the prediction of wear under steady-state operation in the mixed lubrication regime by making use of the load-sharing concept and a modified Archard's wear law. Besides steady-state operation, journal bearings are also subjected to varying operation conditions, e.g., instabilities and starting and stopping [22]. The consideration of the dynamic state of operation is an important aspect within the numerical evaluation of journal bearings.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Wear Phenomena of Journal Bearings by Close to Component Testing and Application of a Numerical Wear Assessment

et al. 2018

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Hydrodynamic journal bearings are subjected to progressively rough loading conditions leading to an increased share of operation in mixed and boundary lubrication. This results in increased frictional losses, additional wear and a higher chance of failure, which calls for the understanding of wear processes and the necessity of a numerical assessment. We conducted wear investigations of journal bearings by making use of a close-to-component test setting, and the progress of wear could be linked to the introduced frictional energy and in combination with a comprehensive surface analysis tribological effects could be resolved in detail. Achieved wear coefficients were implemented in a novelly developed numerical framework, which allows for the dynamic numerical evaluation of operation in the fluid and mixed lubrication regime and simultaneously occurring wear processes. By comparing numerical and experimental results, we evaluated the numerical framework's capability to conduct holistic simulations including aspects like dynamically changing operation conditions, fluid and mixed lubrication as well as wear.

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Numerical analysis on the dynamic behavior of the water-lubricated bearing of the energy recovery turbocharger during start-up

Li,

Ning,

Zhang

et al. 2024

Nonlinear Dyn

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The Behavior of Plain Hydrodynamic Journal Bearings During Starting and Stopping

Cited by 35 publications

References 4 publications

Numerical prediction of the frictional losses in sliding bearings during start-stop operation

Numerical prediction of the frictional losses in sliding bearings during start-stop operation

Evaluation of Wear Phenomena of Journal Bearings by Close to Component Testing and Application of a Numerical Wear Assessment

Numerical analysis on the dynamic behavior of the water-lubricated bearing of the energy recovery turbocharger during start-up

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