National Repository of Grey Literature 49 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Lubrication of knee joint replacement
Sadecká, Kateřina ; Horák, Zdeněk (referee) ; Vrbka, Martin (advisor)
The work deals with the lubrication of total knee replacement using fluorescence microscopy method, which allows unique insight into the contact between femoral and tibial component. The aim was to determine the effect of composition of synovial fluid (i.e. albumin, -globulin, hyaluronic acid and phospholipids) on film thickness and protein behaviour in contact, and also to determine changes of contact area during rotation. Since this is the first experimental work dealing with a knee replacement lubrication primarily, only simple rotation and load cycles were applied by the knee simulator. The output of the experiments was fluorescence intensity, which corresponds to dimensionless film thickness, over time. Another important output are the images directly showing the fluorescently labelled proteins in the contact area. The results show, there are fundamental differences in lubrication in different positions of rotation, due to changes of position, shape and behaviour of the contact area. The composition of the lubricant is also essential, since the proteins themselves form a relatively strong lubricating film and their mixture leads to a substantial reduction of film thickness, due to significant formation of clusters. Complex fluid, although it does not form the strongest layer, is able to create a quite continuous film.
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.
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.
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.
The influence of process fluid on the machining cycle
Ertl, Roman ; Fiala, Zdeněk (referee) ; Kalivoda, Milan (advisor)
The bachelor’s thesis focuses on literature search of problems of process fluids in the machining cycle. The aim of the thesis is to describe the properties of metalworking fluids and their distribution. Subsequently, the requirements for metalworking fluids from different angles of view are described. Process infuences are also discussed in detail on aspects such as temperature, wear, tool durability, etc. Another aim of the thesis is the feeding of process fluid into the machine’s working space and alternatives to process fluids, where MQL and dry machining are included. Great emphasis is placed on protecting the environment and the influence of liquids on the health of the machine operator. Subsequently, the basic maintenance of metalworking fluid sis described, starting with the creation of a new concentrate until their disposal.
Off-board systems for top-of-rail lubrication
Málek, Jan ; Kvarda, Daniel (referee) ; Galas, Radovan (advisor)
This bachelor’s thesis is focused on rail off-board lubrication system. The main part of this thesis is explaining of function and design few certain lubrication systems. In this thesis are explained aspects of wheel-rail contact, such as types and parts of rail, adhesion, slip, creep–traction diagram. Another part of this thesis is description of few certain lubrication system for top of rail and gauge face application. In this thesis are explained product of major companies of friction management industries such as SKF-Lincoln, Whitmore, Loram. Additional part of this thesis speaks about usage and development of this devices in Czech Republic. Output of this thesis is conclusion about advantages and disadvantages these certain devices.
Analysis of THR lubrication with the use of fluorescent microscopy
Tkadlec, Tadeáš ; Daniel, Matej (referee) ; Nečas, David (advisor)
This diploma thesis deals with an experimental analysis of lubrication of total hip joint replacement using fluorescence microscopy, focusing on so-called soft bearing pairs. Experiments were realized using a hip joint simulator, which was modified and refined for fluorescence microscopy. The aim of this diploma thesis was to determine the effect of the individual components of the synovial fluid on the lubrication mechanisms. For this purpose, different model fluids were designed to represent the composition of proteins and other synovial fluid constituents to elucidate the effect of albumin, -globulin and hyaluronic acid on the resulting lubrication performance. The experiments were separate into two categories different in type of load, dynamic (representative walking) and combined (representing standing with short walk). The experimental results were time-dependent fluorescence intensity values, representing dimensionless film thickness parameters. The values were recorded on the graphs and supplemented with fluorescence images taken during the characteristic sections of the measurements. The measured data was subsequently confronted with previously published articles. It was found that the dominant constituent responsible form film thickness is albumin, while -globulin and hyaluronic acid forms thin stable layer enhancing adsorption ability of albumin which contributes to increase of film thickness eventually.
Research of Coatings of Hydrodynamically Lubricated Sliding Bearings for Combustion Engines
Repka, Martin ; Čermák, Roman (referee) ; Petrůj, Jaroslav (referee) ; Havlica, Jaromír (advisor)
Hlavní náplní této dizertační práce je výzkum a vývoj nové povrchové vrstvy pro kluzná ložiska na bázi pevných lubrikantů v polyamid-imidové polymerní matrici se zlepšenými tribologckými vlastnostmi. Podklady pro materiálovou kompozici vzešly z expertízy komerčně dostupného povlaku, respektive jeho povrchovou analýzou v mezných operačních podmínkách. Charakterizace mazného oleje před a po tribotestování společně s detailní povrchovou analýzou dala podmínky pro vznik materiálové formulace. Další část práce se zabývá studiem přípravy a vývojem aplikačního nanášení s přípravou polymerní směsi. Nakonec je popsána studie vlivu sulfidu molybdeničitého a grafitu, jakožto pevných lubrikantů pro zlepšení třecích vlastností a hydroxidu vápenatého pro potenciální zpepšení otěruvzdornosti výsledného povrchu pro palikaci kluzných ložisek.
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.
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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