On the modelling of mixed lubrication of conformal contacts

Bergmann, Philipp; Grün, Florian; Gódor, István; Stadler, Gabriel; Maier–Kiener, Verena

doi:10.1016/j.triboint.2018.03.010

Cited by 35 publications

(18 citation statements)

References 41 publications

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“…Patir and Cheng [27,28] resolved this problem by introducing the averaged Reynolds equation, which allows the consideration of the fluid flow altering effects of rough surfaces by the use of pressure and shear flow factors Φ x,y and Φ s (see Equation (2)). The valid implementation of this equation into COMSOL was subject of the author's former work and is described in detail in [29]. Furthermore, Reference [29] includes details concerning the subsequently described theory and the description of the detailed approach concerning surface evaluation, calculation of flow factors and contact models, which were also used for the current work:…”

Section: Governing Equationsmentioning

confidence: 99%

“…The valid implementation of this equation into COMSOL was subject of the author's former work and is described in detail in [29]. Furthermore, Reference [29] includes details concerning the subsequently described theory and the description of the detailed approach concerning surface evaluation, calculation of flow factors and contact models, which were also used for the current work:…”

Section: Governing Equationsmentioning

confidence: 99%

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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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Section: Governing Equationsmentioning

confidence: 99%

Section: Governing Equationsmentioning

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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“…In the following, the most important information on the simulation models are given. Details can be found in [13] for the macro model and in [25] for the micro model. The EHD macro model is implemented in COMSOL Multiphysics by an FEM-Mesh with around 43,000 elements and uses the original geometry of the shaft specimen and the bearing shells mounted in the bearing shell holders.…”

Section: The Virtual Simulation Modelmentioning

confidence: 99%

“…Using a virtual simulation requires a virtual simulation model containing the components of the tribosystems with specific material and geometry parameters coupled with the boundary conditions at operation (speed, load, and temperature) by mathematical relations. Estimation of friction and mild wear behavior are subjects of implemented virtual simulations of journal bearings [13,14]. Macro models, using elasto-hydrodynamic relations, can be expanded with coupled micro models to take the effects of micro hydrodynamics and solid contact into account [15,16].…”

Section: Introductionmentioning

confidence: 99%

Assessment of Shaft Surface Structures on the Tribological Behavior of Journal Bearings by Physical and Virtual Simulation

et al. 2020

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Optimizing the surface topography of cast iron crankshafts offers the opportunity to use this material as an alternative to steel in high-performance combustion engines. In the past, this was not possible due to the higher wear on bearing shells and the higher friction losses in relation to forged steel shafts. In order to find an optimized shaft micro topography, the friction and wear behavior of steel and cast iron shafts with different surface treatments were compared to each other, using a combined physical (experimental) and a virtual (computational) simulation approach. The experiments were carried out with a rotary tribometer using a journal bearing test configuration with the possibility to test real-life bearing shells and shaft specimens, manufactured from real-life crankshafts. In the experiments, a polished steel shaft with low bearing wear was effective. The optimization of cast iron crankshafts by a novel surface treatment showed a significant reduction of bearing wear in relation to the classical surface finishing procedures of cast iron shafts. A computational simulation approach, considering the real-life micro topography by using the Navier–Stokes equations for the calculation of micro hydrodynamics, supports the assessment of fluid friction. The virtual simulation shows, in accordance to the experimental results, only a minor influence of the investigated shaft topographies on the fluid friction. Further optimization of shaft surfaces for journal bearing systems seems possible only by the usage of patterned micro topographies.

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“…These effects are physically well justified and governed by the Reynolds equation, which is a special variant of the Navier-Stokes-equations. Details regarding the simulation of hydrodynamic friction can be found in respective publications [30][31][32].…”

Section: Deep Neural Network (Dnns)mentioning

confidence: 99%

Lubrication Regime Classification of Hydrodynamic Journal Bearings by Machine Learning Using Torque Data

2018

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Hydrodynamic journal bearings are used within a wide range of machines, such as combustion engines, gas turbines, or wind turbines. For a safe operation, awareness of the lubrication regime, in which the bearing is currently operating, is of great importance. In the current study, highspeed data signals of a torque sensor, sampled with a frequency of 1000 hz in a time range of 2.5 s, obtained on a journal bearing test-rig under various operating conditions, are used to train machine learning models, such as neural networks and logistic regression. Results indicate that a fast Fourier transform (fft) of the highspeed torque signals enables accurate predictions of lubrication regimes. The trained models are analysed in order to identify distinctive frequencies for the respective lubrication regime.

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On the modelling of mixed lubrication of conformal contacts

Cited by 35 publications

References 41 publications

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

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

Assessment of Shaft Surface Structures on the Tribological Behavior of Journal Bearings by Physical and Virtual Simulation

Lubrication Regime Classification of Hydrodynamic Journal Bearings by Machine Learning Using Torque Data

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