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Suitable lubricants for deep drawing of stainless steel
Mück, Jonáš ; Staněk, Vojtěch (referee) ; Lidmila, Zdeněk (advisor)
The intention of this thesis is the experimental evaluation of different lubricants and their suitability for deep drawing of stainless steel 1.4404. The testing method is based on the friction model at the point of drawing edge and retainers. This model corresponds with a structure of testing fixture. The suitability of every single lubricant for this application has been determined by comparison of the output, which is dependance of the strength on the track with the reference results. The testing has been performed on many different samples provided by various manufacturers. The best result was measured with the oil Kalorex AT 650 S, manufactured by AT Oil, which belongs to the group of environmentally harmful lubricants. Based on the results of this experiment we can conclude that chlorine content significantly increases the lubrication capability especially under high pressure. The modification of preparation geometry which presumes the elimination of certain undesirable disturbances accompnaying the experiemnt has been also proposed.
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Friction components produced by rapid prototyping
Pečenka, Tomáš ; Škaroupka, David (referee) ; Omasta, Milan (advisor)
The main aim of this bachelor thesis is to make an overview of use of additive technology for production of friction components. The first part is concerned on review of additive methods and type of materials. In the second section are situated applications of this technology for fabrication of friction components. The main goal of last part is research in area of tribology of parts manufactured by additive technology.
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Reduction of Contact Pairs Friction Losses
Novotný, Marek ; Raffai, Peter (referee) ; Maršálek, Ondřej (advisor)
This bachelor thesis deals with the topic of mechanical efficiency of contact pairs in the crankshaft of the combustion engine. The introductory section focuses on the efficiency of the combustion engine as a whole. In addition, it describes the areas where mechanical losses primarily occur. The following chapters describe mechanism of friction losses, the main factors affecting their amount and the most modern ways to increase mechanical efficiency. In the closing chapter, some basic computing relations, describing the size of mechanical losses are listed. The aim of this thesis is to acquaint the reader with the importance of mechanical efficiency in the area of combustion engines.
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Evaluation of lubricants for forming
Svobodová, Hana ; Podaný, Kamil (referee) ; Lidmila, Zdeněk (advisor)
The aim of this diploma thesis is experimental testing and evaluation of the suitability of lubricants for drawing stainless chromium - nickel austenitic steel X5CrNi18-10 and comparison of the results obtained from the work [51]. The testing was performed by modeling the friction between the traction edge and the retainer, which corresponds to the real production process at ACO Industries. The introductory part of the thesis describes the process of deep drawing, followed by a description of tribology and the effect of friction. The individual types and properties of lubricants are described in more detail. The main part of the work deals with the testing of lubricants. The results are then described and evaluated.
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Methods for improving frictional features of rubbing surfaces
Fojtík, Jakub ; Černý, Michal (referee) ; Šamánek, Otakar (advisor)
This bachelor thesis describes several methods of improving surface's tribological properties. There are many forms of tribological processes, depending on structure, geometry, material properties, relative motion and loading of system elements. The main aim is to minimize wear and friction. It can be controlled by improving surface structure, geometry and by increasing of surface roughness with coating deposition methods, chemical-heat treatment and surface texturing. These methods can be also used for reparation of degraded rubbing surfaces or for surface modification in order to establish suitable lubrication conditions. An introduction to micro/nanotribology and tribological processes in micro/nanoscale is also described in this study.
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Design of Wheel Flange Lubrication Experimental Apparatus
Nepovím, Radovan ; Dzimko, Marián (referee) ; Hartl, Martin (advisor)
The diploma thesis deals with construction design and practical realisation of experimental apparatus for investigation of wheel flange track vehicle lubrication. Experimental apparatus in full-scale uses optical interferometry for investigation of lubrication behaviour in wheel flange contact. It is an innovative approach which has not been used for such experiments so far. The aim of the following measurement with this apparatus is to determine the minimal amount of ecological lubrication in wheel flange contact under certain conditions when there is no lubrication film interruption. The apparatus enables to measure real rail wear. This work contains the apparatus description for the study of wheel flange lubrication, wheel flange contact specifications, the description of its influence on wear and acoustic emission, and a detailed description of the experimental apparatus.
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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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Experimental study of artificial articular cartilage friction
Kulíšek, Vlastimil ; Ranuša, Matúš (referee) ; Rebenda, David (advisor)
Many conventional materials are used to replace damaged articular cartilage, which are beginning to be replaced by innovative biomimetic materials that mimic cartilage properties. One of these materials are poly(vinyl alcohol) (PVA) hydrogels crosslinked by freeze-thawing and cast-drying method. These hydrogels possess similar mechanical as articular cartilage. In order to clarify the effect of kinematic conditions on the friction of hydrogels, three levels of sliding speed and load and a uniform lubricant – PBS were chosen. The coefficient of friction of the FT hydrogel decreased with increasing load. The dependence of the sliding speed did not show a uniform trend and corresponded to the adsorption-repellent model for PVA gels. The coefficient of friction of the CD hydrogel increased with increasing sliding speed according to the repulsion-adsorption model for PVA gels. The increase in load at low sliding speeds of CD hydrogel caused a slight decrease in the coefficient of friction. At the highest speed, there was an optimal load at which a low coefficient of friction was achieved. The CD hydrogel showed a lower coefficient of friction than cartilage. The FT hydrogel achieved a lower coefficient of friction than cartilage only at 5 N and 10 mm s- 1. This work contributes to the understanding of the tribological properties of PVA hydrogels.
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Effect of Surface Texturing on Friction and Film Thickness under Starved Lubrication Conditions
Ali, Fadi ; Kaneta, Motohiro (referee) ; Glovnea, Romeo (referee) ; Hartl, Martin (advisor)
Tato disertační práce se zabývá vlivem mělkých mikro-textur na tření a tloušťku filmu v mazaných nekonformních kontaktech za extrémních podmínek a za podmínek hladovění kontaktu. Měření byla realizována na tribometru v konfiguraci ball-on-disk. Kontakt byl pozorován pomocí vysokorychlostní kamery. Pro stanovení součinitele tření byl využit snímač krouticího momentu. V této studii byly popsány dva typy mikrotextur – mikrovtisky a příčné mikrodrážky. Výsledky naznačují, že za podmínek hladovění vedou mikrovtisky ke snížení tření a to díky nárůstu tloušťky mazacího filmu. Mechanismus doplňování mikrovtisků čerstvým mazivem je pravděpodobně způsoben kapilárními jevy ve vstupní oblasti. Třecí plochy s příčnými mikrodrážkami, jejichž délka byla menší než průměr Hertzova kontaktu, potom obecně vykazovaly lepší tribologické parametry ve srovnání s hladkými povrchy. Příčné mikrodrážky vedly k výraznému nárůstu tloušťky mazacího filmu za podmínek hladovění i za extrémních provozních podmínek (protisměrný pohyb). Numerické simulace přechodových jevů příčných mikrodrážek ukázaly dobrou shodu s experimentálními výsledky.
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Design of experimental device for visualization of axial forces in bolted connections
Ptáček, Tomáš ; Galas, Radovan (referee) ; Svoboda, Petr (advisor)
In the bachelor's thesis is created design experimental device that will be able to measure preload in bolted joints. The first part of thesis deals with research study of the current state of knowledge of bolted joints, depending on the use of different types of lubricants. According to informations, 3 different variants are introduced. The selected variant is described in detail with their advatnages and disadvantages. The final design is developed into technical drawing and electronic 3D models.
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