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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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Lubricants created by nature
Drobilič, Ivo ; Urban, Filip (referee) ; Nečas, David (advisor)
This bachelor thesis provides an overview of substances which can be considered as the lubricants in its natural environment. The first part of the thesis of focused on lubricants in human body. The substances such as water, blood or synovial fluid are analysed in a detail. The following chapter deals with lubricants in everyday life. As the example, decrease of tyre adhesion in case of rain or longer breaking distance of trains as a consequence of presence of leafs on rails, can be mentioned. The last part, in addition, summarizes the lubricants which are based on natural products.
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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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Cam-follower contact
Urban, Filip ; Zimmerman, Martin (referee) ; Šperka, Petr (advisor)
This bachelor thesis deals with construction design of a cam-follower contact simulator. At the beginning of the thesis there is a brief overview of cams, forces acting in valve train system and types of cam-follower contact wear. There is also review of other apparatuses developed for cam-follower contact research. Main part is devoted to construction design, variants of design and calculations.
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