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Lubricant Gap Shape Optimization of the Hydrodynamic Thrust Bearing
Ochulo, Ikechi ; Vacula, Jiří (referee) ; Novotný, Pavel (advisor)
The objective of this Master's thesis is to find, using genetic algorithm (GA), an optimal profile for lubricating gap of a thrust bearing of a turbocharger. Compared to the analytical profile, the optimal profile is expected to have minimized friction for an equivalent load capacity. Friction minimization is one way to increase the efficiency of the thrust bearing; it reduces the friction losses in the bearing. An initial problem was given: a thrust bearing with Load capacity 1000 N, inner and outer radii of 30mm and 60mm respectively, rotor speed of 45000 rpm and angle of running surface of $0.5^0$. Lubricant properties were also provided for the initial problem: oil density of $ 840 kg/m^3$, dynamic viscosity $(\eta)$ of 0.01 Pa.s With this data, the numerical solution of the Reynolds equation was computed using MATLAB. To obtain more information, the minimum lubricating gap thickness was also computed using MATLAB. With this information, the shape of the analytical profile, and its characteristics were found. The analytical profile was then used a guide to create a general profile. The general profile thus obtained is then optimized using GA. The characteristics of the generated profile is then computed and compared to that of the analytical profile.
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Lubricants in Up-to-date Combustion Engines
Čech, Martin ; Svída, David (referee) ; Dundálek, Radim (advisor)
In my bachelor work I have tried to analyze informations about lubricants in up to date combustion engines. This work deals with motor oils and their viscosity and performance classification The special motor oils for motorcycles are part of this bachelor work too. One of the aims of bachelor work provide informations about gear oils for automatic as well as manual transmissions and their classification. This work describes also questions about additives.
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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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Effect of synovial fluid composition and surface topography modification on lubrication of joint replacements
Hekrle, Pavel ; Vampola, Tomáš (referee) ; Vrbka, Martin (advisor)
The main objective of this diploma thesis is to determine the influence of synovial fluid compodition and the influence of surface microtextures on lubrication of hip join replacements. For all experiments, hip joint simulator based on the pendulum principle was utilized. Metal heads (CoCrMo) manufactured by B Braun company and and tailor made acetabular cups from optical glass were used as contact couples. Acetabulum dimensions were fabricated according to dimensions of real implants. Experiments with surface microtextures simulated walking cycle for 210 s and development of lubrication film over time was observed.Results have shown that all types of tested structures improved lubrication of contact area, where the best results were obtained for square and triangle shapes respectively. Second set of experiments was based on the fact, that the composition of synovial fluid of healthy people differs from the composition of patients with various stages of osteoarthritis. Therefore, experiments with different model fluids were compared, which in their composition correspond to different groups of patients. For the model fluid that corresponds to the largest number of cases, experiments with individual components and combinations thereof were subsequently performed to provide a more detailed description of how these components affect the film-forming mechanism. The results show, that a change in fluid composition of patients with osteoarthritis can have a major negative effect on fluid formation process within the pair.
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An investigation of lubrication of knee joint replacement
Sýkora, Tomáš ; Horák, Zdeněk (referee) ; Nečas, David (advisor)
This diploma thesis deals with an experimental analysis of knee joint replacement lubrication. The experiments were realized at a knee joint simulator which can apply conditions according to certain standard and survey the phenomena by using fluorescence microscopy. The aim of thesis is to clarify the influence of particular components of synovial fluid on the lubrication process. The intensity of fluorescence expresses dimensionless parameter of a lubrication film thickness. There was a fundamental study with mineral oils before the experiments with the synovial fluid. The study allows to have a look at contact transformation during walk. Results are shown in graphs as dependency of intensity on time, including pictures showing phenomena in the contact zone. Experiment results show that protein -globulin creates a layer on the surface. There is albumin on the layer and it makes the lubricating film thicker. The protein interaction is supported by hyaluronic acid and fosfolipids which stabilizes the created structure. According to lubrication is behaviour of film related to a complex structure of synovial fluid. Thesis gives more information about behaviour of synovial fluid and can be used for future development of knee replacements.
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Plant oils for industry
Beran, Vojtěch ; Ficza, Ildikó (referee) ; Frýza, Josef (advisor)
This bachelor thesis describes usability of plant oils as liquid greases. The beginning of thesis follow up tribology problems and process of lubrication. The main section describes plant oils from perspective of their chemical composition and its closely related properties. In this thesis, plant oils are compared with another common liquid oils together with the comparison of its properties on specific application. In the conclusion, the thesis deals with summary of plant oils issues and with prospects for the future.
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Construction of gears with plastic teeth
Selzer, Tomáš ; Vrbka, Martin (referee) ; Křupka, Jiří (advisor)
The thesis discusses the matter of construction of gear trains using plastic parts in both lubricated and non-lubricated environment, trying to give an overview of an up-to-date information in the process. Nowadays, thanks to several years of development, polymer-based gear systems can be used in many cases as a replacement for metal-based ones. The undeniable advantage of such replacement is mostly the lower production cost and its lower weight, which, together with favorable friction properties of polymer materials, makes a number of technological applications much more effective. The first part is dedicated to listing and defining the typical characteristics of polymer materials, which are essential in the process of designing the gear. The next part focuses on evaluation of the available types of solutions for plastic gear trains construction. The last topic is centered around possible defects and the wear as well as the operation conditions and a real-life application of such plastic gear system. The most notable findings are summed up and commented on in the form a discussion. Thanks to the chosen topic, the bachelor’s thesis adds to a closer understanding of the construction and operation of the plastic gear systems.
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Advanced Solution to Piston Assembly Dynamics
Dlugoš, Jozef ; Furch,, Jan (referee) ; Kučera, Pavel (referee) ; Novotný, Pavel (advisor)
Hlavní cíl této práce je vyvinout pokročilý výpočtový model dynamiky pístové skupiny. Kontakt mezi pístem a válcem je zprostředkován skrz vrstvu maziva nebo pomocí kontaktu nerovností. To vede k různým režimům mazání, tudíž k různým silovým interakcím působících na plochy kontaktní dvojice. Během řešení hydrodynamiky a kontaktu nerovností, je nutné zahrnout deformaci pístu a válce do výpočtu—přirozeně iterační proces. Jelikož požadavky na výpočtovou síť kontaktních sil a deformaci těles se liší, byl navržen robustní mapovací algoritmus. Výsledky vyvinutého výpočtového nástroje jsou experimentálně verifikovány. Pro tento účel je uskutečněno měření sekundárního pohybu pístu pomocí laserových snímačů vzdálenosti. Měření je vykonáno na experimentálním motoru s bočním vedením ventilů a průhlednou hlavou válce, aby byl přítomen kompresní tlak ve spalovací komoře. Naměřený boční pohyb pístů je znehodnocen. Proto je další analýze potrobeno pouze úhlové natočení pístů. Shoda mezi naměřenými a vypočítanými výsledky variuje pro různé části pracovního cyklu. Dobrá shoda je dosažena během komprese a expanze. Naopak výrazné rozdíly nastávají, když boční síla dosahuje nízkých hodnot: sání a výfuk. Hlavní přínos této práce je vytvoření výpočtového nástroje, který je schopný zahrnout výše popisované jevy, které mají podstatný vliv na dynamiku pístové skupiny. Bohužel to vede k dlouhým výpočtovým časům, zvláště když je zahrnuta deformace. Tento problém řeší navržený paralelní výpočet. To je založeno na paralelizaci podprogramu během vyčíslování citlivostní analýzy. Tímto způsobem je řádově redukován výpočtový čas.
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Formula Student Turbocharger Lubrigation
Novotný, Tomáš ; Špičák, Milan (referee) ; Janoušek, Michal (advisor)
This bachelor thesis deals with turbocharger´s bearing housing lubrication. The first part is focused on searches about this topic, it describes parts of lubrication system and ways of oil distribution. The next part deals with design of independent lubrication system for Formula student car´s turbocharger, in particular design of gerotor pump and it´s pressure regulator.
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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.
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