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Rolling bearings for electromobility
Mbontar, Patrik ; Frýza, Josef (referee) ; Šperka, Petr (advisor)
The aim of this bachelor thesis is to describe the problems related to the use of rolling bearings in electric vehicles. Introduction includes history, distribution, and a brief description of the bearings. In the next section, there will be a description of the use, requirements and parameters for rolling bearings of combustion engine cars. In the main part of the thesis, the parameters and requirements of bearings used in electric vehicles and hybrid vehicles will be analyzed. I will continue with familiarization with dynamic actions affecting bearings and their critical requirements. In conclusion, the two types of cars and the possible development of this type of bearings will be compared.
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The Effect of Synovial Fluid Constituents on Friction and Lubrication of Articular Cartilage
Čípek, Pavel ; Dr. Prashant K. Sharma (referee) ; Muňoz, Anna Neus Igual (referee) ; Vrbka, Martin (advisor)
Práce se zabývá problematikou biotribologie modelu synoviálního kloubu. Cílem práce je popsat vliv složek synoviální kapaliny na formování mazacího filmu v modelu synoviálního kloubu. Práce je zaměřena na experimentální analýzu součinitele smykového tření a jeho propojení s pozorováním adsorbovaného mazacího filmu v kontaktu pomocí fluorescenční mikroskopie. Součástí práce je návrh tribometru, který umožňuje vizualizaci v průběhu experimentů. Tribometr je vyroben, kalibrován a verifikován pomocí komerčního tribometru. Dále je součástí práce návrh metodiky experimentů včetně návrhu postupu pro zpracování a hodnocení výsledků. Pro zpracování záznamu z vizualizace kontaktu byl navržen speciální software, který pracuje na principu segmentace obrazu. Poslední část práce je zaměřena na aplikaci vyvinuté metodologie spolu s nově navrženým tribometrem, což umožňuje posoudit roli složek modelové kapaliny u formování mazacího filmu v modelu synoviálního kloubu. Experimentální část je založena na měření tření za současné vizualizace kontaktu. Tato práce prezentuje originální výsledky rozšiřující oblast biotribologie synoviálního kloubu, které mohou pomoci dalšímu rozvoji účinné léčby pacientů s nemocnými klouby.
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Effect of femoral head size on friction and lubrication in THR
Bartošík, Jan ; Dzimko, Marián (referee) ; Vrbka, Martin (advisor)
This diploma thesis concerns itself with the experimental study of friction and lubrication in the artificial hip joint depending on the head size. Measurements were made in a hip joint simulator based on the principle of pendulum. For the friction measurements artificial joints, made from three material combinations and two diameters, from two companies were used. The measurements show that the material combination has a more significant effect to friction coefficient than the head size. Using a bigger head size shows a decrease in friction coefficient for all material combinations when compared to a smaller head size. For the measurement of lubrication film the colorimetric interferometry was applied. A metal-on-glass contact pair was used, where the glass cups were made according to the real measurements of the joint cups. Four types of hip replacements with diameters of 28 and 36 mm with two different diametral clearance were measured during a constant motion of 210 seconds. Measurements show, that the lubrication film in the hip joint with a small diametral clearance increases very fast over the 800 nm value. Contact surfaces in the hip joint with a large diametral clearance aren’t separated by the lubrication film, resulting in a damage of the chromium coating in cup. A thick lubrication film results in a higher friction coefficient, when compared with hip joints with a very thin or no lubrication film.
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Friction of compliant contacts
Vala, Martin ; Galas, Radovan (referee) ; Nečas, David (advisor)
This bachelor’s thesis deals with the study of the friction of compliant contacts and parameters affecting it. First section of this thesis provides analysis of current problematics with friction and compliant materials. In the next section basic definition of friction, compliant material and compliant contacts is provided with an actual study of up-to-date articles. Last section of this thesis is discussion dealing with all the articles and pointing out the influencing parameters. Followed by potential research pathways.
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Lubricants for bicycle chains
Brychta, Ondřej ; Navrátil, Václav (referee) ; Svoboda, Petr (advisor)
This bachelor thesis deals with the lubrication of bicycle chains. The introduction describes the basics of the friction processes, then there is an analysis of the chains used on bicycles, used materials, analysis of forces and wear in the chains. The last part is devoted to the properties of basic types of lubricants, their additives and the possibilities of their use in cycling.
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Base frame´s oil system under the steam turbine and generator
Petržela, Zdeněk ; Vlašic, František (referee) ; Mazal, Pavel (advisor)
This bachelor thesis describes problematics of the lube system of steam turbines as an important part for its operation. The beginning of the thesis offers an overview of steam engine and steam turbine development both at home and abroad and its working cycle. The main part of the thesis discusses lube system functions and components. Next section contains a summary of required turbine oil properties and effects that affect the oil during working cycle. The conclusion of the thesis is focused on lube system operating problems, their causes, consequences and recommendations for their preventing.
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Experimental study of friction and lubrication in THR
Urban, Filip ; Čermák, Jan (referee) ; Vrbka, Martin (advisor)
This work analyzes problems of friction and lubrication of total hip replacement (THR). At first, experimental study of friction coefficient under various conditions was conducted using hip joint simulator based on principle of pendulum. After that, lubrication film development was observed, using colorimetric interferometry with head from THR and glass cup with respect of geometry and clearance to cups made originally for THR. With respect to research study [25] it was found that increasing contact conformity leads to increased film thickness. Also protein adsorption on articulating surfaces was observed. Thanks to adsorption 80 nm film thickness was measured even if relative surface speed was zero. Furthermore protein aggregation was observed on the border of contact zone, similar aggregations were observed by Myant et al. [29] or Vrbka et al. [25]. These aggregations are formed when lubricant is under shear stress and it can positively affect film thickness. If the relative motion of articulating surfaces is not sufficient, the protein layer can`t be refreshed enough and film thickness start decreasing. Coefficient of friction 0,13 was measured when lubricating film development was observed. Close to this value are material combinations metal on polyethylene and metal on metal.
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Nanolubricants for practical applications
Sochor, Ondřej ; Frýza, Josef (referee) ; Svoboda, Petr (advisor)
This bachelor thesis is concerned with describing nanolubricants and enhancing their characteristics using suitable additives, such as nanoparticles. These can improve their tribological properties and reduce mechanical wear and friction between two surfaces. This thesis summarizes manufacturing, some features and mechanisms that apply to nanoparticles and nanolubricants. The main outcome of the work is a synthesis of acquired knowledge in the field of nanolubricants for the purpose of practical application and description of current trends in its research as being used as additives.
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Characteristic Piston Ring Failures and Their Corrective Methods
Orság, Josef ; Knotek, Jiří (referee) ; Raffai, Peter (advisor)
This Bachelor's thesis concerns the most common failures of piston rings. The first part of this thesis focuses on the design of a piston ring and on the load affecting it. The second part describes various kinds of lubrication. This section also shows, which lubrication states occur during operation of internal combustion engines. And final part is devoted to the most common failures of the piston rings and how to prevent them.
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