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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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Tribological behavior of detonation nanodiamond dispersed in lubricants
Dočekal, Martin ; Čermák, Jan (referee) ; Svoboda, Petr (advisor)
Currently tribological laboratories are looking for a new type of solid ingredients, to create a lubricating composition with minimal friction, heat resistant, with particles well dispersed in oils, sedimentation stable, improving the running properties and to minimize the concentration of solids. Nanodiamonds (DND) could exhibit the possible solution. These particles (in nanometers size) have very good physical and chemical properties, high hardness and resistance. The main advantages are effectiveness at low concentrations, compatibility with various types of oils or environmental safety (carbon additive, unlike metal) in a comparison with other types of additives. However, it is necessary to study these ingredients. The aim of research was to examine the influence of diamond nanoparticles on friction in a lubricated contact (elastohydrodynamic mode). Using tribological equipment, 3D optical profilometer and a microscope, we compared and evaluated using oil with diamond nanoparticles as well as without them. The research focused on the behavior of nanoparticles in contact and the effect they have on friction. To assess these properties of nanodiamonds, EHD optical tribometer was used (this is a device designed for the study of thin lubricating films). 3D optical profilometer and a microscope to assess the wear. And to determine the relationship between the coefficient of friction (COF) and time, Mini Traction Machine was used.
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Oils for combustion engines
Dzurenda, Ján ; Novotný, Pavel (referee) ; Maršálek, Ondřej (advisor)
Bachelor's thesis deals with information search of the current state of knowledge in the field of lubrication of combustion motors, i.e. lubrication systems and oils for combustion motors. The introduction of work focuses on the issue of lubrication systems, theirs partitions by methods of lubrication and description of the main parts of the lubrication system. Next part is focused on the oils of motors. In this part is referred to division of motor oils, requirements for motor oils and characteristics of motor oils. Follow part describes issues associated with the lubrication of combustion motors. Part cites main factors that affect the properties of motor oils i.e. fuel, water, glycol and dirt. Further is processed problem of motor working i.e. temperature, amount and consumption of oil. The last part describes the issues of biodegradability and actual requirements of application for motor oils.
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Surface Treatment Methods of ICE Piston Rings
Hora, Otakar ; Maršálek, Ondřej (referee) ; Raffai, Peter (advisor)
This bachelor's thesis focuses on surface treatments of piston rings. The first part focuses on piston rings in general and their operating status. The second part focuses on the materials and technologies, characteristics and properties of surface treatments of the working area of piston rings. The final part contains the comparison of currently used surface treatments of piston rings.
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Lubrication of hip joint replacements
Rebenda, David ; Hartl, Martin (referee) ; Vrbka, Martin (advisor)
This thesis deals with the experimental study of lubrication of hip joint replacements. The influence of the synovial fluid composition and the head material to the lubricating film thickness were asssesed by using a pendulum hip joint simulator. Both of these effects were assesed under static and dynamic loading conditions. The experimental results showed that the movement of the head against the cup is unnecessary for the separation of the rubbing surfaces by a layer of adsorbed proteins. Composition of the synovial fluid then significantly influences the thickness of the lubricating film. Two opposite extremes have been observed during tests with two model synovial fluids. The first fluid formed a very strong lubricating film. The second sample almost prevent adsorption of proteins and consequently formed only very thin lubricating film. The influence of the material is noticeable when comparing the results obtained with a metal head and ceramic heads. Metal head formes under the same conditions thicker lubricating film. This evidence may be partly influenced by different diametrical clearances, which were in the case of ceramic heads higher.
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Design of spindle for lathe
Sovadina, František ; Marek, Tomáš (referee) ; Pavlík, Jan (advisor)
The thesis deals with the design and construction of headstocks of a turning centre. The aim is to design a spindle with an output of 20 kW and a maximum speed of 5000 1/min. The research part of the thesis is focused on the description of the basic parameters of the headstock and turning centres needed for the construction of the headstock and contains an analysis of the available spindles on the market. The next part of the thesis deals with the selection and calculation of cutting conditions and the necessary parameters. Analytical calculations are then verified using FEM analysis. At the end of the thesis, a 3D model was developed and headstock drawing documentation.
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Thin metal coating of polymer materials
Zatloukal, Filip ; Furmann, Denis (referee) ; Nečas, David (advisor)
The study of compliant contacts from a tribological standpoint is very complicated due to low reflectivity and electrical conductivity of materials such as polymers or rubber. These properties significantly limit the possibilities of using conventional methods which are being used to study the film formation and lubricant flow. To enable the use of the conventional methods it is necessary to apply a thin reflective layer on the non-reflective surface. This work evaluates the current literature dealing with the coating of polymeric materials. A method was chosen based on the analysis of the currently available technologies, which is used to apply a thin reflective layer on the polydimethylsiloxane sample. This part is followed by a feasibility study to clarify the effects of the coating on friction processes. This work can significantly contribute to the field of compliant contacts, especially in terms of clarifying the mechanisms of lubrication.
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Reduction of Valvetrain Mechanical Losses
Kučera, Pavel ; Píštěk, Václav (referee) ; Novotný, Pavel (advisor)
The topic of this thesis is the mechanical losses in the valvetrain. The purpose is to describe the creation of individual losses and their possible reduction. The main factor of creation of losses is friction. The result of this thesis is to highlight the possible methods to reduce friction and other influences acting on the valvetrain. The main benefit is description various types of surface and design modifications of valvetrains, which are already used or are in development.
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History of hip joint replacements
Kohout, Jiří ; Urban, Filip (referee) ; Vrbka, Martin (advisor)
In this bachelor´s thesis is solved problem of friction, lubrication, wear and history of hip replacement. History is described from the second half of 18th century and there was an effort to include every important milestones that affected development of the alloplastic of hip joint. Beside this development is also observed volume wear of hip joint. History of lubrication and friction is watched from first experiment, which measured these factors it means mid-20th century.
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