National Repository of Grey Literature 52 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Experimental investigation and numerical modelling of top of rail products
Kvarda, Daniel ; prof.Roger Lewis (referee) ; Meierhofer, Alexander (referee) ; Hartl, Martin (advisor)
Tato disertační práce se zabývá experimentálním a numerickým studiem maziv pro temeno kolejnice. Tyto maziva se používají ke snížení opotřebení, hluku a zlepšení energetické účinnosti kontaktu kola a kolejnice. V posledních dvou desetiletích byl proveden rozsáhlý experimentální výzkum týkající se použití maziv pro temeno kolejnice. Avšak velmi málo výzkumu bylo zaměřeno na základní mechanismy těchto produktů, zejména na problémy s nízkou adhezí. Aplikace matematických modelů v této oblasti také nebyla dosud zkoumána. Cílem této práce je pomocí matematického modelu vysvětlit třecí chování a problémy s nízkou adhezí maziv pro temeno kolejnice. Model předpokládá jak tření vznikající interakcí nerovností pevných látek, tak separaci mazacím filmem. Validace tohoto modelu byla provedena na experimentálním tribometru se schopností měřit tloušťku filmu pro ověření přesné predikce separace povrchu. Komerční tribometr byl použit ke zkoumání vlivu jednotlivých složek v mazivu pro temeno kolejnice na bázi oleje. Sada reologických testů v kombinaci s modelem ukázala, že pevné částice měly velmi malý vliv na zvýšení adheze po aplikaci. Následně byly testovány různé typy maziv pro temeno kolejnice pomocí vysokotlakého torzního zařízení. Mezný režim tření těchto látek byl hodnocen představeným modelem. Bylo zjištěno, že pozitivní třecí vlastnosti, které by tyto produkty měly poskytovat, jsou výsledkem velké skluzové vzdálenosti, která mění složení třecí vrstvy. Nízký koeficient tření v důsledku nadměrné aplikace se vyskytl při stejném aplikovaném množství u všech testovaných látek. Tato diplomová práce představuje původní výzkum rozšiřující znalosti o produktech pro temeno kolejnice.
Design of device for material antiseizure testing
Burk, Filip ; Kvarda, Daniel (referee) ; Šperka, Petr (advisor)
Friction between materials can be partially eliminated by lubrication between surfaces. In order to select the correct lubricating oil, it is necessary to have the necessary test means to make an evaluation. One of these is a four-ball tester, which is lacking at the BUT Institute of Design. The aim of the bachelor thesis is the design of a modification of the existing tribometer R-MAT 3 for a four-ball configuration. The review part includes a description of the preparation, measurement and evaluation of the four-ball tester and an evaluation of conventional testers. The design of the ball mounting, drive and torque transfer to the tribometer spindle was carried out. Measurement and recording of friction torque, contact force and temperature during the test was also proposed. The result is a configuration ready for implementation. The review section includes a description of the preparation, measurement and evaluation of the four-ball test and an evaluation of conventional testers.
Wear analysis of the sliding surface material of large-scale hydrostatic bearings
Daněk, Lukáš ; Robenek, Dětřich (referee) ; Svoboda, Petr (advisor)
This thesis focuses on the experimental investigation of the wear behavior of sliding surface materials in large-scale hydrostatic bearings during oil supply failure. The aim is to clarify the influence of materials and surface treatments on friction and wear. For this purpose, a testing methodology was designed and implemented in laboratory conditions. An experimental module was developed for the tribometer to simulate a critical state and a new procedures were established for evaluating the behavior of the contact. Wear results were observed using a profilometer, precise scales, and a microscope. A set of suitable materials for pad sliding surfaces was created, which were tested under critical conditions. The selected materials were representatives of construction steel and anticorrosion treatments (galvanization), soft and hard (aluminium) bronzes, composite bearing linings (Babbitt), polymers (UHMWPE), and composite materials (PTFE). The experimental results show the dependence of friction on sliding velocity, wear rate, and other phenomena repeatedly measured on a statistical sample of selected materials. The final result is a list of characteristics, limitations, and recommendations for the tested sliding materials, which can be used for more effective design and operation of large-scale hydrostatic bearings.
Determination of anodizing parameters for surface properties of aluminum alloys
Paclík, Eduard ; Vaverka, Ondřej (referee) ; Košťál, David (advisor)
The bachelor's thesis deals with the determination of basic parameters for anodizing aluminum alloys. The introductory passages include an overview of aluminum alloys suitable for anodization, theoretical and practical assumptions of anodic oxidation. The main experimental part discusses the laboratory anodic oxidation of aluminum alloy samples under different parameters of surface roughness, current density, and voltage. Anodically oxidized samples were tested on special UMT tribometer and Contour GT-X profilometer devices for friction coefficient measurement and surface inspection. The measurement results were used to determine the dependence between surface roughness of aluminum alloys and the quality of the anodized layer, the dependence between current density of the anodic process and the quality of the anodized layer, and the dependence between voltage and the quality of the anodized layer. The problem was solved within the possibilities of FSI laboratory conditions. The thesis serves as a basic orientation in this field.
Lithic function and its application in archeology
Krásná, Soňa ; Popelka, Miroslav (advisor) ; Květina, Petr (referee) ; Hroníková, Linda (referee)
The goal of the thesis is to find the way how to apply use-wear analysis as well as functional analysis to archaeological assemblages of selected artefacts from Central European archaeological contexts, namely lithics (chipped stone artefacts) and obtain the greatest potential from the analysis. Thesis consists of: current state in the field of functional studies research worldwide, method of use-wear application in connection with material science knowledge, especially tribology. Use-wear analysis is applied to the selected lithic artefacts from Paleolithic to Eneolithic Periods. The results of this work are based on the following microscopic approaches: low power approach (LPA), high power approach (HPA), scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). There are described and stated differences in potential of above mentioned approaches in connection with specific archaeological artefacts (assemblages of artefacts). The question answered in the conclusion is how to apply the above mentioned methodological approaches in application to various archaeological materials (period, number, context etc.) to obtain the greatest informational potential from the material analysed. Work is concluded with specific terminology from the field of tribology and use-wear analysis...
Measurement of friction coefficient between damping wire and groove
Šnábl, Pavel ; Pešek, Luděk ; Bula, Vítězslav ; Běhálek, V. ; Boháč, T. ; Tašek, H.
Damping wire is being used on railway wheels for noise suppression. It is inserted into a groove of the wheel and dry friction damping reduces vibrations and thus the noise transmitted by the wheel. For increase of durability of the wire, surface treatment of the groove and the ring must be applied to prevent corrosion. Three combinations of diferent surface treatments were studied during reciprocating motion in a set of measurements with diferent frequencies and normal forces to evaluate friction coeficient. Then, those measurements were repeated after a long-time run to evaluate the change of friction coeficient after the wear of the surfaces.
Influence of fuel additives for passenger cars
Obytová, Eliška ; Bradáč, Albert (referee) ; Bilík, Martin (advisor)
This diploma thesis deals with the addition of automotive fuels and their effects. The aim was to evaluate the function and efficiency of fuel additives present in the fuel at gas stations, and subsequently to improve the fuels accordingly by adding additional individual chemical compounds. The theoretical part explains the concepts, functions and processes related to fuel additives and the basics of tribotechnology. The practical part deals with the process of testing the properties of fuels, their functions, additional additives and its impact for practical use.
Nanolubricants for practical applications
Sochor, Ondřej ; Frýza, Josef (referee) ; Svoboda, Petr (advisor)
This bachelor thesis is concerned with describing nanolubricants and enhancing their characteristics using suitable additives, such as nanoparticles. These can improve their tribological properties and reduce mechanical wear and friction between two surfaces. This thesis summarizes manufacturing, some features and mechanisms that apply to nanoparticles and nanolubricants. The main outcome of the work is a synthesis of acquired knowledge in the field of nanolubricants for the purpose of practical application and description of current trends in its research as being used as additives.
Analysis and Evaluation of Surface Texture Effects of Tested Samples
Fuciman, Lukáš ; Dobrocký, David (referee) ; Sedlák, Josef (advisor)
The thesis deals with an evaluation of the surface texture of various materials, created by machining technologies (turning, milling and grinding). As for the theoretical part of the thesis, it contains a theoretical analysis of the effect of surface texture on friction, wear, coating and lubricating properties. The main emphasis is put on the analysis of the most frequently evaluated profile and surface parameters as well as their possible influence on the functional areas of machined parts. The experimental part includes evaluated and compared measured data based on the monitored parameters with benefits for machinery industry.
The effect of proteins on friction of artificial articular cartilage
Plachý, Tomáš ; Nečas, David (referee) ; Rebenda, David (advisor)
This bachelor thesis deals with the influence of the composition of synovial fluid on the coefficient of friction of artificial cartilage. The effect of protein concentration and their combination with other components of synovial fluid on the coefficient of friction of CD hydrogels simulating artificial cartilage is observed. All experiments were performed at a constant load of 10 N, speed 10 mm / s, temperature 37 ° C. In experiments investigating the effect of a combination of hyaluronic acid and phospholipids together with proteins, concentrations corresponding to a healthy individual were used. In experiments where the effect of the proteins themselves and their own combinations was investigated, concentrations corresponding to both a healthy individual and patients with advanced osteoarthritis or patients with aseptic release of the prosthesis were used. The work shows that when using the proteins alone, or their combination, there is a decrease in concentration of friction coefficient with increasing concentration. However, if hyaluronic acid alone or phospholipids alone is added to the protein, the coefficient of friction increases. The reduction occurs only after the addition of the combination of acid and phospholipid.

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