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Monitoring the influence of concrete composition on abrasion resistance
Černá, Hana ; Novosad, Petr (referee) ; Bodnárová, Lenka (advisor)
This diploma thesis focuses on the resistance of concrete to abrasion with regard to the raw materials used for their production. In the theoretical part of the thesis are described admixtures, different types of aggregate and aggregate composition which influence the resistance of concrete to abrasion. In the experimental part, 15 different C30 / 37, S4 concrete formulations were proposed. Different types of aggregates - fecal gravel (Žabčice), biotic granodiorite (Olbramovice) and amphibolite (Želešice) have always been used in the recipes. Fine ground limestone, micro-silica, high-temperature fly ash and finely ground slag were ingredients that were added to the proposed recipes. Consistency was determined by the method of cone seating and the density of fresh concrete. In the hardened state, concrete density, compressive strength, bending tensile strength, tensile strength, watertightness, concrete absorption, and abrasion resistance were determined using the Böhm method and wide wheel method. The test specimens were tested after 7, 28, and 90 days of maturation.
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Wear regimes of aluminium alloys
Slivka, Václav ; Zapletal, Tomáš (referee) ; Šperka, Petr (advisor)
This thesis deals with the research of the wear regimes of the selected aluminium alloy in the conditions of dry friction. The aim of this work is the evaluation of the measure of an abrasive and adhesive wear of this alloy. This evaluation is made from the experiments which are made on the base of the knowledge of the research study. The dependence of the wear on the sliding speed and load, the friction on the sliding speed and load and the dependence of the normalised pressure on the normalised speed, so called the map of wear, are given on the base of the results of the measure.
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Effect of toothpaste abrasiveness on friction and wear of dental fillings
Formánková, Pavla ; Čípek, Pavel (referee) ; Vrbka, Martin (advisor)
This bachelor thesis dealt with research, that links dental hygiene issues with tribology. The aim of the thesis was to analyze the effect of abrasive particles of toothpastes on friction and wear of dental fillings. The friction coefficient was evaluated in a tooth brushing simulation on an UMT TriboLab tribometer that lasted 260 minutes. The tribological system consisted of a toothbrush, a sample of composite material and a solution of artificial saliva with a selected toothpaste. Each paste was defined by an RDA value from 0 to 250, expressing the degree of abrasiveness therefore the ability of the toothpastes to wear the material. Wear was analysed on a Bruker Contour GT-X optical profilometer. From the measured values it was found that the influence of abrasive particles is significant in terms of wear of dental fillings. For both the friction coefficient and the material loss when measured only in the presence of artificial saliva, the resulting values were generally lower. However, the material loss in the toothpastes measurments did not increase linearly with the RDA value as expected. Literature studies and measurements have shown that this may be due to other factors affecting wear. Future research on these factors could lead to the selection of more gentle toothpastes in dentistry and thus prevent the increase in wear of dental fillings
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Development of abrasion resistant concrete
Procházka, David ; Darebník, Zdeněk (referee) ; Hela, Rudolf (advisor)
The resistance of concrete to abrasion is an important feature particularly for transport and water management structures where the surface is exposed to abrasion. Bachelor thesis deals with individual influences on improvement of abrasion resistance of concrete surface. Furthermore, the search of test methods used for testing abroad. In the practical part, we assess the effect of curing agents on resistance to abrasion, water jet and tensile strength by tear-off test.
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Bank stabilization of Brno Dam
Václavovský, Filip ; Pelikán, Petr (referee) ; Šlezingr, Miloslav (advisor)
The aim of this bachelor‘s thesis is to design stabilizations of the banks of the Brno‘s water reservoir, damaged by abrasion. This work is focused on the most damaged Osada area located on the left bank. Shore abrasion is caused by fluctuations in water levels and the effect of wind waves. Result of this thesis are biotechnical stabilizations, which has to stop or slow the symptoms of abrasion.
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HEAT – MECHANICAL DEGRADATION OF SURFACES AT THE HIGH TEMPERATURES
Zahradník, Radek ; Hajduk, Daniel (referee) ; Čecho, Ladislav (referee) ; Toman,, Zdeněk (referee) ; Raudenský, Miroslav (advisor)
The Ph.D. thesis is focused on a surface degradation mechanisms under combined heat and mechanical load. The objects of examination are work rolls from hot rolling mill which suffer such a load. In first chapter, the hot rolling process, the design, the manufacturing process and present materials of work rolls are described. The state-of-the-art study of work roll surface degradation mechanisms – wear, oxidation, thermal and contact fatigue are described in the second chapter. The characterization, the formation, the mechanisms of progression and the effects of each surface degradation mechanism is described step by step. The state-of-the-art study of analytical and numerical models which are related to hot rolling process is described in third chapter together with their limitations and flaws. The next chapters contain design of an analytical, an optimized macroscopic and a microscopic model for study of the work roll stress state. The macroscopic and the microscopic model is based on finite element method and they are implemented in ANSYS Programming Design Language. The models are used to process several case study which are based on previous experimental work of the Heat transfer and fluid flow laboratory. The results from case studies specify and expand the knowledge of work roll stress state. The results show the portion of each loading factor on the whole stress state. In addition, time and depth depended distribution of stress state is presented. The results from macrosferic model illustrate the cause of spalling and a rupture of the work roll. The results from the microsferic model show the cause of creation of the to-surface-parallel cracks within carbides of high chromium irons. Last chapter summarized of all results gathered from case studies together with the goals for further research definition. The necessary steps for further cognition are stated. The thesis contains a large set of appendixes with deeper discussion of several related topics. These appendixes represent the one third of whole the thesis.
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Proposal to revitalize the banks of the flooded Hulín sandstones - section 2
Čuda, Ondřej ; Pelikán,, Petr (referee) ; Šlezingr, Miloslav (advisor)
The subject of this bachelor’s thesis is to prevent the retreat of the bank line by the proposal of suitable biotechnical stabilization of the banks of the flooded Hulín sandstones on the specified section. Shore abrasion is mainly caused by the starting wind, which results in the formation of waves that subsequently spread the banks. The result of the thesis is the processing of biotechnical stabilization proposals, which are intended to reduce or slow down the retreat of the bank lines.
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Classification and evaluation of rail wear
Nohel, Rostislav ; Frýza, Josef (referee) ; Galas, Radovan (advisor)
This bachelor’s thesis is focused on the wear of rails. In this thesis, the reader will be firstly introduced to the fundamentals such as nomenclature of wheel and rail, adhesion, adhesion coefficient, contact area, slip, traction characteristic and wear. Subsequently, the fundamental types of material wear (adhesive, abrasive and fatigue) will be explained, which occur in the wheel-rail contact. In the next part, the individual rail defects are analysed with respect to locations. The output of the bachelor’s thesis is overview and description of the most common rail defects which are usually caused by fatigue wear.
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Stabilization of the flooded sand pit near Hulín
Patková, Aneta ; Pelikán,, Petr (referee) ; Šlezingr, Miloslav (advisor)
The aim of this bachelor thesis is to assess the current state of the bank damaged by abrasion of the flooded gravel and sand pit in Hulín with the subsequent proposal of suitable biotechnical or biological stabilization and hydrological calculations to determine the prognosis of the prognosis retreat of the coast. As part of the field survey, photo documentation of abrasive log cabins caused by wind waves and water level fluctuations was taken. Part of the work is also the proposal of a total of six stabilization measures, the construction of which should prevent or slow down the effects of abrasion.
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