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Effect of surface roughness on lubrication of plain bearings
Vaněk, Tomáš ; Hartl, Martin (referee) ; Šperka, Petr (advisor)
This work investigates the influence of surface roughness on the lubrication of axial hydrodynamic bearings with convergent wedge gaps. It focuses on situations where operational conditions allow for full separation of surfaces by the lubricating film, as well as the transition to mixed lubrication. The aim is to understand the impact of surface roughness on the hydrodynamic lubrication process and whether their proper selection can affect the friction and load-carrying capacity of the bearing. Experimental measurements are used to determine the influence of parameters, where the thickness of the lubricating film is captured through fluorescence microscopy, along with the friction force at the contact between the pin and the test sample. The samples form a wedge gap with a rotating saphire disk, and the investigated surface roughness parameters include orientation, height Sq, and skewness Ssk (i.e., the relative ratio of depressions and protrusions). According to the obtained results, the orientation, height, and shape of roughness are key factors influencing hydrodynamic lubrication. However, the orientation alone does not determine the contact behavior, and additional roughness parameters must be considered for a complete understanding of the phenomenon. Increasing surface roughness negatively affects lubrication, but the proper combination of Ssk and orientation can minimize this effect. This work represents one of the first experimental measurements examining the influence of surface roughness on hydrodynamic lubrication. The findings have applications not only in plain bearings, but also in other components such as wet couplings or other sliding interfaces using hydrodynamic lubrication.
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Experimental study of lubricant films in contact of machine parts
Kučera, Ondřej ; Křupka, Ivan (referee) ; Vaverka, Michal (advisor)
This bachelor thesis is focused on the description of methods for experimantal study of lubrication films in contact of machine parts, particularly for non-conformal surfaces, for which elastohydrodynamic and mixed of lubrication is typical. The methods are devided according to measured quantity into the methods for film thickness measurement, contact pressure measurement and temperature measurement. It was described the principle of these methods, the equipment, application and characteristics. Finally, evaluation of current status and further development are included.
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Experimental study of lubricant films in contact of machine parts
Kučera, Ondřej ; Křupka, Ivan (referee) ; Vaverka, Michal (advisor)
This bachelor thesis is focused on the description of methods for experimantal study of lubrication films in contact of machine parts, particularly for non-conformal surfaces, for which elastohydrodynamic and mixed of lubrication is typical. The methods are devided according to measured quantity into the methods for film thickness measurement, contact pressure measurement and temperature measurement. It was described the principle of these methods, the equipment, application and characteristics. Finally, evaluation of current status and further development are included.
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