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Experimental study of friction modifiers in rail transportation
Knápek, Jiří ; Dzimko, Marián (referee) ; Galas, Radovan (advisor)
The adhesion in the wheel-rail contact can be effectively controlled by using the friction modifier. Adhesion control can reduce excessive wear of the contact bodies or noise. The essence of this diploma thesis is to determine the optimal amount of friction modifier in wheel-rail contact depending on the climatic and operating conditions. For experimental study of the behavior of the friction modifier, the twin-disc device is used. Twin-disc simulates and controls the most important operating parameters such as speed, slip, attack angle or contact pressure. On the basis of these findings, the off-board top-of-rail lubricator system was designed. This system controls the amount of friction modifier according to current climatic and operating conditions.
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Numerical Simulations of Dynamic Loads in Wheel-Rail Contact with Shape Irregularities
Jandora, Radek ; Malenovský, Eduard (referee) ; Schmidová, Eva (referee) ; Janíček, Přemysl (advisor)
During life of railway vehicles, shape irregularities develop on wheels and rails because of wear. The shape irregularities then affect forces in wheel-rail contact and cause further damage of contact surfaces, vibrations and noise and increase risk of derailment. A numerical simulation of railway vehicle motion with more details on contact surfaces geometry was created to investigate dynamic contact loads in wheel-rail contact. A variety of methods can be used to evaluate forces in rolling contact, the method chosen for this study was algorithm CONTACT based on boundary element method. Four studies are presented in this papers: contact loads from a wheel with a flat and with a wavy tread pattern, loads on wavy rail and load in a curve. The first three studies investigated effects of existing wear patterns, the last one looked for cause of common wear pattern developing on rails. Results of the studies with worn components used showed that the worst kind of shape irregularities is a flat present on wheel. This type of shape cause loss of contact and following impacts. The study of ride in curve showed that cause of high wear in curves, especially those with small radii, is caused by vibration of wheelset. This vibration is then caused by different length of inner and outer rail and wheels travelling along a different path.
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Analysis of the effect of friction modifiers composition on adhesion and noise in rail transport
Suchomel, Ondřej ; Galas, Radovan (referee) ; Klapka, Milan (advisor)
The aim of this bachelor thesis is experimental study of influence of composition of water based friction modifier on adhesion and sound pressure level. Experiments are carried out on twin-disk device. Introductory experiments are conducted to determine the conditions for further experiments. The experiments of the individual components follow, and the various friction modifier compositions are tested. From the results, it is obvious that a significant influence on the reduction of adhesion coefficient and sound pressure level has solid lubricant.
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Materials for friction modification within wheel-rail contact
Pláněk, Miloslav ; Kvarda, Daniel (referee) ; Galas, Radovan (advisor)
Problematic aspects of wheel-rail contact can be reduced by application of substances for friction modification. The essence of this bachelor’s thesis is compile overview of substances for friction modification applied on Top of Rail with focus on that one, which are applied to decrease excessive wear and noise. In this thesis, the reader will be firstly introduced to the fundamentals of wheel-rail contact, essence of friction management and partition of substances for friction modification. Next part of the thesis is focused only on substances providing intermediate level of friction. These substances are TOR friction modifiers, TOR lubricants and TOR solid compositions. Thesis describes their composition, ways of application, expected benefits and map commercial products available on the market. The output of the bachelor’s thesis is overview of these substances and their comparison based on theoretical assumptions, test´s results and practice experience. The thesis will allow reader to have better market orientation between available products, which could be wrong tagged by their own producers.
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Development of a tribometer for the adhesion measurement on a real rail
Vodehnal, Michal ; Polach, Pavel (referee) ; Omasta, Milan (advisor)
The submitted master’s thesis describes the development of a tribometer used to measure the adhesion of a real rail. The thesis contains an overview of the basic terms concerning wheel and rail contact. Following that, there is an overview of devicesthat are able to measure the adhesion on a real track. The author's solution includes a design of the tribometer, the proposed measurement methodology and also a description of the individual components. The result of this thesis is a functional device, verified in laboratory conditions and on a real track.
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Experimental Study of Wheel Flange Lubrication
Frýza, Josef ; Dzimko, Marián (referee) ; Omasta, Milan (advisor)
This diploma thesis deals with the experimental study of the influence of operating conditions on the tribological aspects of the wheel flange and rail gauge contact. The wheel flange contact occurs when the vehicle moves on a curve track and it leads to severe up to catastrophic wear regime. For effective reduction of wear is important to apply a suitable amount of lubricant at appropriate intervals into the contact. The issue in this work comprehensively studies using of three laboratory apparatus and six methods that are theoretically and experimentally compared. Assessed are friction, wear, distribution and film thickness of lubricants for different contact conditions. The resulted amount of lubricant and interval of its application eliminates development of seizure at low consumption of lubricant. The understanding of mechanisms that occur in the wheel-rail contact not only helps to reduce operating costs and improved to energy efficiency of movement of vehicle on a track, but it is the basis for safe, reliable and ecological operation of rail transport.
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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.
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Twin-disc machine for the study of wheel-rail wear and rolling contact fatigue
Šperlich, Vilém ; Skurka, Šimon (referee) ; Galas, Radovan (advisor)
Presented thesis describes the design of an experimental device used for the study of wear and contact fatigue of wheel-rail contact. The text describes selected devices already used for the study of wheel-rail contact. The main part of the text focuses on choosing a suitable conceptual variant and the design of the resulting twin-disc machine with linear contact. The final design enables easy mounting of the specimens and their precise positioning. The final part of the text contains calculation of estimated price of this device.
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Development of a tribometer for the adhesion measurement on a real rail
Vodehnal, Michal ; Polach, Pavel (referee) ; Omasta, Milan (advisor)
The submitted master’s thesis describes the development of a tribometer used to measure the adhesion of a real rail. The thesis contains an overview of the basic terms concerning wheel and rail contact. Following that, there is an overview of devicesthat are able to measure the adhesion on a real track. The author's solution includes a design of the tribometer, the proposed measurement methodology and also a description of the individual components. The result of this thesis is a functional device, verified in laboratory conditions and on a real track.
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Materials for friction modification within wheel-rail contact
Pláněk, Miloslav ; Kvarda, Daniel (referee) ; Galas, Radovan (advisor)
Problematic aspects of wheel-rail contact can be reduced by application of substances for friction modification. The essence of this bachelor’s thesis is compile overview of substances for friction modification applied on Top of Rail with focus on that one, which are applied to decrease excessive wear and noise. In this thesis, the reader will be firstly introduced to the fundamentals of wheel-rail contact, essence of friction management and partition of substances for friction modification. Next part of the thesis is focused only on substances providing intermediate level of friction. These substances are TOR friction modifiers, TOR lubricants and TOR solid compositions. Thesis describes their composition, ways of application, expected benefits and map commercial products available on the market. The output of the bachelor’s thesis is overview of these substances and their comparison based on theoretical assumptions, test´s results and practice experience. The thesis will allow reader to have better market orientation between available products, which could be wrong tagged by their own producers.
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