National Repository of Grey Literature 90 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
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.
Design of impact microviscometer
Nepovím, Radovan ; Svoboda, Petr (referee) ; Hartl, Martin (advisor)
The bachelor thesis deals with engineering design of mechanical parts of impact microviscometer. Impact microviscometer is intended for educational tool for the study of rheological properties of lubricants in the laboratory in VUT Brno. The bachelor contains a brief summary has designed equipment and measuring methods used, restrictions of engineered apparatus, designs of constructional variation and description of constructional parts of the apparatus.
Design of Elastomer/Glass Contact Experimental Apparatus
Štipák, Patrik ; Svoboda, Petr (referee) ; Hartl, Martin (advisor)
This bachelor thesis deals with project, manufacture and assembly of construction of experimental device – simulator of softEHD contact between elastomer and glass. This device will serve as research facility of lubricating layer thickness and frictional force at the contact. Similar solutions of other authors are mentioned in this thesis. Technical documentation is included.
High Pressure Viscometer
Skalický, Lukáš ; Hartl, Martin (referee) ; Křupka, Ivan (advisor)
The master´s thesis describes design of falling ball high pressure viscometer for measurements of rheological properties of liquids under high pressure and in the wide temperature range. The design is based on similar apparatuses, which are described in literature. The speed of falling sinker is measured by two optical senzors. Apparatus allows measuring of viscosity, density and optical observing structure of liquid. There was developed extensive program for the evaluation of measurement in Matlab. Apparatus is placed in the laboratory of the Institute of Machine and Industrial Design FME BUT and is used for research and creative activities.
Animation of 2D gear meshing
Fiala, Vlastimil ; Klapka, Milan (referee) ; Hartl, Martin (advisor)
The bachelor thesis deals with the animation of planar involute gearing. The thesis gives a theoretical basis for understanding the problems of gears. Introduction of the work is focused on the description of the geometry and mesh of uncorrected planar gears focusing on the line of action. Gradually meshing of gear pairs with external, internal and rack gearing is described. Following part describes mesh of planar wheel with manufacturing rack, thus creating teeth flanks by rolling. The next section describes the problems of interference with the root curve and its impact on the gear's teeth number. The last part deals with correction of teeth by shifting profile and its effect on meshing ratios.
Research on the textured journal bearings for engines in automotive
Svoboda, Martin ; Hartl, Martin (referee) ; Omasta, Milan (advisor)
The aim of this thesis is to describe the effect of surface textures of radial journal bearings with polymer coating on friction and damage development using experimental tests. Wear and friction tests of real bearings with different texture geometries and surface materials were performed. It was found that the wear deterioration of the textured aluminum sliding bearing surface and neutral or positive effects on the wear of the textured bearing with polymer coating. The reason for the improvement is the good resistance to high pressures of the polymer coating and the preservation of the texture dimensions throughout the bearing run. The friction test showed an improvement in the frictional properties of the textured surfaces when the amount of lubricant in contact was insufficient. At the same time, a positive effect on tribological properties was demonstrated by reducing the lateral lubricant discharge.
Study of starvation in a grease-lubricated elastohydrodynamic contact
Kuňák, Jiří ; Hartl, Martin (referee) ; Svoboda, Petr (advisor)
This diploma thesis is an experimental study of grease lubrication in a starved elastohydrodynamic lubricated (EHL) contact. Lubricating film thickness is measured with tribological experimental device ball-on-disc using optical interferometry and high speed camera. The experiment is aimed at a comparison of results acquired by ball-on-disc device and full scale axial bearing. In addition, this paper also investigates the influence of number of the rolling elements (overrolling time) on the resulting film thickness.
Design of impact microviscometer
Junek, Jan ; Zimmerman, Martin (referee) ; Hartl, Martin (advisor)
This thesis treats the design and practical realization of the impact microviscosimeter construction. In the thesis there is stated the synopsis of the ten to date existing experimental devices meant for the study of rheological features of lubricants. There is elaborated their technical and developmental analysis with the description of used measuring method. It also includes basics calculations, the size of Hertz contact region and the size of the force loading, which are necessary for the design and construction of this particular device. The part of this thesis is the technical documentation.
In-situ Study of Surface Topography Changes in Elastohydrodynamic Contact
Šperka, Petr ; Dzimko, Marián (referee) ; Návrat, Tomáš (referee) ; Dobeš, Petr (referee) ; Hartl, Martin (advisor)
This dissertation thesis deals with elastohydrodynamic lubrication (EHL) of surfaces with real roughness. Systematic study of surface harmonic components behaviour, during their passage of the EHL contact, by other authors led to retrieval of a uniform principle according which individual harmonic components deform inside the contact. Although the amplitude attenuation model can provide rapid tool for more accurate surface assessment in design process it has not been validated on real surfaces till now. The thesis represents pioneering work on quantitative analysis of real surfaces EHD measurements. It contains original and new results with real and model roughness features that in many cases confirm theoretical expectations. Deeper understanding of surface roughness behaviour inside EHL contact, which is typical for machine parts like bearings, gears, cams etc., can help to improve design process of the components and ultimately enable machines and equipment to work with lower energy requirements and higher durability.
Design of the device for research on lubrication of gears
Žáček, Jan ; Hartl, Martin (referee) ; Svoboda, Petr (advisor)
The master´s thesis is focused on the design and implementation of the laboratory stand for studying lubrication of gears. Specifically, to assess the effect of lubricant contamination on gears. The device uses the Niemann closed circuit concept which in practice is called „back to back“. Firstly, in the theoretical part, the test circuits uses for testing gears are described and one of the standardized procedure for experimentation is presented. Based on research studies, basic parameters for the design and creation of conceptuals are determined. The practical part consists not only the design of this stend, but also including test run and the description of the procedure on that device. The result of this master´s thesis is the functional experimental device for the future development of intelligent lubrication systems.

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