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Evaluation of machine elements surface topography by optical profilometer
Vrána, Jakub ; Křupka, Ivan (referee) ; Šperka, Petr (advisor)
This thesis deals with the issue of surface texture topography of engineering parts. Research provides general view of surface texture topography evaluation and puts the aforementioned into the context of international standards. In the practical part of this thesis, an experiment is implemented. With help of optical interferometer, parameters are measured and their robustness is evaluated. In the conclusion part of this thesis, acquired information are evaluated and resumed.
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Using of detonation nanodiamond in tribology research field
Mauer, Milan ; Křupka, Ivan (referee) ; Svoboda, Petr (advisor)
The main objective of this bachelor thesis is to give a general knowledge about nanodiamonds, which are chipped off during the explosions diamonds. These particles are used as additions in lubricating preparations to decrease the friction. Bachelor thesis summarizes the basic characteristics, methods of manufacture and application nanodiamonds in practice. Part of this thesis is dedicated to theoretical and detailed descriptions of procedures and experimental results in nanodiamonds field of study. Another part describes different types of nanoparticles, used for the same purpose as nanodiamonds. The final part sums up the advantages of nanoparticles and its purpose for experimental or practical usage.
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Experimental Study of Lubrication Films Formation During Start-up and Reversal Motion of Rubing Surfaces
Svoboda, Petr ; Dzimko, Marián (referee) ; Čermák, Jan (referee) ; Dobeš, Petr (referee) ; Křupka, Ivan (advisor)
This dissertation is focused on the effects of both artificially produced and real roughness features on mixed lubrication film formation during start-up and reversal of non-conformal contacts operated under rolling/sliding conditions. The start-up operation of mixed lubricated contacts represents one of the transient conditions that bring the risk of the surface damage because of asperities interactions. Chromatic interferograms captured by CMOS high-speed camera during start up of the motion enabled to observe the detailed changes in lubrication film caused by surface features. The observation of the effects of surface dents artificially produced on the ball surface helped to understand better the behaviour of real surface topography. It was found that the presence of shallow surface features can help to separate mixed lubricated rubbing surfaces more efficiently than it could be suggested from the results obtained with smooth surfaces. It can be suggested from the obtain results that properly designed topography of the rubbing surfaces can help to reduce the asperities interactions under transient operational conditions.
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Film thickness distribution during the start-up of smooth surfaces.
Manga, Martin ; Křupka, Ivan (referee) ; Svoboda, Petr (advisor)
Bachelor thesis is engaged in experimental study of start-up of smooth surfaces under the conditions of mixed and elastohydrodynamic lubrication. Start-up is non-stationary process, whereat the surface doesn’t need to completely separated with lubrication film. Therefore it exists a real risk of failure. Study summaries all present studies and extends with own experiment on the equipment of tribological laboratory. The evaluation of the experiment was made by chromatic interferometry. This method is used to measure thin lubrication films. Experiment for miscellaneous values of acceleration confirms the findings of previously studies.
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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.
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Study of the effects of ellipticity parameter on lubrication film shape
Pavlík, František ; Dzimko, Marián (referee) ; Křupka, Ivan (advisor)
Diploma thesis deals with elastohydrodynamic lubrication of point contacts, which surfaces are influenced by topography and velocity vector of one rubbing surface is misaligned. Author summarizes knowledge of previously published research articles, which fundamentally enrich current state of knowledge. Diploma thesis contains experimental measurement results of the film thickness and the way of lubrication film formation in elliptical contact for different ellipticity parameters, kinds of rubbing surfaces and angles of the velocity vector. New findings have helped to better understand the behaviour of highly loaded lubricated contacts taking place in machine components and completed the current state of knowledge with results that can be used in next thorough study of this issue.
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Programmable illuminating system for an optical microscope
Lošťák, Martin ; Křupka, Ivan (referee) ; Chmelík, Radim (advisor)
A programmable illuminating system (PIS) uses a commercial multimedia projector together with a suitable optical relay system in order to illuminate specimens under microscope with transmitted light. The theoretical part of the diploma thesis describes some methods used in the optical transmission microscopy. All of these methods employ physical masks placed in the condenser front focal plane. In the case of the traditional methods the masks are used to enhance contrast (e.g. dark-field illumination) and resolution (oblique illumination). One of the methods (a condenser with rotating aperture) provides the information about the three-dimensionality of the specimen. The next part of the thesis contains the theory and the basic classification of the illuminating systems used in the optical transmission microscopy. An optical and mechanical design of the optical relay system used for PIS is introduced. The experimental part shows the results made with two different PIS arrangements. It was shown on two different specimens that the PIS provides the same illumination as the classical methods. It was also proved that the PIS can simulate the rotating aperture in the condenser front focal plane and thus to give the information about the three-dimensionality of the specimen. Some new static and dynamic illuminating methods were introduced.
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Surface texturing of rubbing surfaces
Chlachula, Petr ; Čermák, Jan (referee) ; Křupka, Ivan (advisor)
Surface texturing of rubbing surfaces represents the way how to increase tribological performances by improving the lubrication film formation and diminishing friction and wear. Its application in machine components requires detailed understanding of the mechanism taking place between rubbing surfaces in microscopic scale. This diploma thesis is focused on the processes taking place in tribology systems to consider the possibility of surface texturing applications in highly loaded machine parts operated under transient operational conditions.
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THIN LUBRICANT FILMS STUDY USING SPECTROSCOPIC REFLECTOMETRY
Čudek, Vladimír ; Dzimko, Marián (referee) ; Navrátil, Karel (referee) ; Dobeš, Petr (referee) ; Křupka, Ivan (advisor)
ectroscopic reflectometry is measurement technique that enables the study of the thickness and refractive index of thin layers. This thesis deals with its use for the study of lubrication films within EHD contact and verifies a new approach suggested in recent publications. It is focused on the development of an optical arrangement and mathematical model for the lubrication film thickness measurement within the entire EHD contact. This technique brings the possibility to study the pressure distribution within the contact area through the evaluation of changes in lubricant refractive index.
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