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Mechanisms Involved in the Formation of Secondary Structures on the Friction Surface of Experimental Aluminum Alloys for Monometallic Journal Bearings
Open AccessArticle

Theoretical and Experimental Investigations on Transient Run-Up Procedures of Journal Bearings Including Mixed Friction Conditions

Institute of Tribology and Energy Conversion Machinery, Technische Universität Clausthal, Leibnizstr. 32, 38678 Clausthal-Zellerfeld, Germany
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Lubricants 2018, 6(4), 105; https://doi.org/10.3390/lubricants6040105
Received: 31 October 2018 / Revised: 22 November 2018 / Accepted: 27 November 2018 / Published: 1 December 2018
This paper focuses on the operating behavior of journal bearings for industrial machinery application during run-ups. For this purpose, a numerical simulation code that is based on a two-dimensional extended and generalized Reynolds equation and a full three-dimensional energy equation, was advanced by a theoretical model considering the effects of mixed friction and warming of journal components during start-up. The mixed friction routine contained the elastic half-spaces model proposed by Boussinesq, which considers the influence of rough surfaces by implementing flow factors and calculates additional stiffness and dissipation in areas with solid interactions. Furthermore, a transient term was added in the energy equation to consider the thermal inertia of journal, and bearing to ensure a realistic heating during run-ups. Results of the prediction were compared to experimental data taken from a special test rig built up for validation procedures. Besides the conventional sensors for temperature, oil flow, and relative motion between shaft and stator, a contact voltage measurement was installed to determine the intensity of mixed friction. The evaluation of experimental data by Stribeck curves, based on a shaft torsion measurement, indicated a significant influence of run-up time on frictional moment. The friction coefficient of the rotor bearing system was strongly influenced by the run-up time. A short run-up time reduced the frictional coefficient in the mixed lubrication regime while the opposite behavior was observed in the hydrodynamic lubrication regime. The numerical code predicted these tendencies in good agreement with experimental data, however, only if the transient energy model was applied. View Full-Text
Keywords: journal bearing; run-ups; mixed friction; transient energy equation; experimental validation journal bearing; run-ups; mixed friction; transient energy equation; experimental validation
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MDPI and ACS Style

Prölß, M.; Schwarze, H.; Hagemann, T.; Zemella, P.; Winking, P. Theoretical and Experimental Investigations on Transient Run-Up Procedures of Journal Bearings Including Mixed Friction Conditions. Lubricants 2018, 6, 105.

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