|
|
Development of Film Thickness in Elastohydrodynamically Lubricated Compliant Contacts
Křupka, Jiří ; Fillot, Nicolas (referee) ; Glovnea, Romeo (referee) ; Křupka, Ivan (advisor)
Mazání polymerních strojních součástí, jako jsou polymerní ozubená kola, je v současné době předmětem zájmu mnoha strojírenských aplikací z hlediska simulace mazacích procesů a optimalizace tribologických podmínek pro zvýšení výkonnosti těchto součástí. Předkládaná disertační práce se zabývá experimentální studií vývoje tloušťky kapalinového filmu v elastohydrodynamicky mazaných poddajných kontaktech. Hlavním cílem práce je objasnit formování tloušťky filmu v poddajných kontaktech v přechodové oblasti (TR) mezi isoviscous-elastic (I-E) a piezoviscous-elastic (P-E) režimem elastohydrodynamického mazání (EHL). Za tímto účelem byly provedeny laboratorní experimenty na rotačním optickém tribometru v konfiguraci kulička na disku, ve kterých byla implementována metoda optické chromatické interferometrie. Experimentálně byl analyzován vliv jak reologické odezvy maziva, tak konstitutivní viskoelastické odezvy polymeru na tvorbu tloušťky kapalinového filmu. Na základě výsledků byla dokumentována nízká platnost predikčních modelů tloušťky filmu I-E a P-E v oblasti TR. Výsledky prezentované v této práci rozšiřují poznatky o tvorbě mazacího filmu v poddajných kontaktech pracujících v režimu EHL a mohou tak být zohledněny při návrhu polymerních strojních součástí nebo při řízení mazacích procesů.
|
|
|
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.
|
|
|
Bearings for space
Vavřík, Petr ; Nečas, David (referee) ; Košťál, David (advisor)
Currently, space satellites in orbit are required to operate reliably for more than 10 years. This places high demands on the satellite's tribological systems, which must function properly in the hostile space environment for this period. This bachelor thesis deals with the description of suitable bearings and their lubrication for space applications. Lubrication regimes are described at the outset. Then, space factors affecting the proper operation of tribological systems are summarized. The largest part is devoted to the description of the most used bearings and lubricants. The thesis concludes with the design of suitable bearings and their lubrication for the satellite reaction wheel.
|
|
|
User interface design of software application for simulation of EHD problems
Sýkora, Ota ; Poliščuk, Radek (referee) ; Ficza, Ildikó (advisor)
This bachelor thesis deals with the design and implementation of user interface of software application for simulation of elastohydrodynamic lubrication (EHL) problems. The first part of the thesis briefly reviews EHL simulations and describes the numerical method used for the application. The second part of the thesis provides an introduction into graphical user interfaces and describes the design and implemenation of the actual application in Qt Creator.
|
|
|
Study of lubrication films formation under starved lubrication conditions
Košťál, David ; Hartl, Martin (referee) ; Křupka, Ivan (advisor)
The purpose of this thesis is to reveal production mechanisms of lubrication films between non-conformal surfaces in situations, when is not possible to designate lubrication regime as fully flooded elastohydrodynamic contact. Under certain conditions of lubrication volume, rolling speeds, temperatures, lubrication properties or loads could lubrication film decrease under values determined by fully flooded formulas. This regime is designated as starvation at it includes risk of increased wear. In this thesis the methodology and the new simulator of starving contact are described. Obtained film thickness results are compared with existing numerical models.
|
|
|
Simulation of point contact lubrication by finite element method
Hrdonka, Štěpán ; Čermák, Jan (referee) ; Šperka, Petr (advisor)
This diploma thesis is concerned with simulation of elastohydrodynamic lubrication of point contacts using the finite element method. The first part of the thesis focuses on the study of the issue and introduces equations for model creation and numerical methods which can be used for EHD calculation. The most suitable solution approach has been chosen from the overview, namely the Full system approach. The software we chose for applying the method was COMSOL Multyphysics. The following part of the thesis deals with model’s creation and gives its elaborate description. We introduce models for calculation of line and point EHD lubrication for newtonian lubricants and, last but not least, we also present a model for calculation of point contact EHD lubrication for non-newtonian lubricants. The next part of the thesis then verifies all the models. That is achieved by comparing the calculated results to results from different papers. The conclusive part of the thesis then examines the matches of acquired results to different prediction relationships and experiments.
|
|
|
Design of clamping fixture for ball and spherical-roller speciments
Vodrada, Tomáš ; Ali, Fadi (referee) ; Zimmerman, Martin (advisor)
The bachelor thesis deals with engineering design of positioning and loading part of experimental apparatus that is meant for studying of rheological properties of lubricants in VUT Brno. The thesis contains a brief summary of devices designed up to now including short descriptions of their function, engineering requirements, designs of constructional variations and descriptions of parts of designed device.
|
|
|
Analysis of lubricated compliant contact
Dočkal, Kryštof ; Dzimko, Marián (referee) ; Nečas, David (advisor)
This diploma thesis deals with the proposal of methodology for film thickness eva- luation within compliant contacts. With respect to characteristics of such contact pairs, like variable film thickness, high surface roughness, or poor conductivity and reflectivity, the usage of conventional experimental methods is particularly complicated. In present study, an optical method based on the principle of fluo- rescent microscopy was employed in present thesis. An evaluation algorithm in- volving background normalization and calibration of fluorescent intensity to film thickness was created in a form of experimental software. The proposed algori- thm was validated by using elastohydrodynamic contact formed between ceramic ball and glass disc. The measured film thickness was compared with theoretical prediction, while very good agreement of obtained data was observed. Further, a series of experiments with compliant samples was conducted, while the central film thickness was evaluated as a function of mean speed, applied lubricant, ap- plied load and slide-to-roll ratio. The last part of the thesis is focused on results analysis and discussion considering the previously published literature.
|
|
| |
|
|
Effect of surface texturing on starved contact
Jordán, Jakub ; Náhlík, Luboš (referee) ; Křupka, Ivan (advisor)
The diploma thesis deals with the analysis of the effects surface texturing on starved contact. Experimental verification was realized on apparatus simulating contact between a steel ball and glass disc using colorimetric interferometry and high-speed camera. The work deals with lubrication regimes, problems with starved contacts and surface texturing which can reduce effects of starvation on non-conformal surface contacts.
|
guest ::
