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Identification of material constants of new rubber damping segments from modal analysis of a railway rubber damped wheel
Šulc, Petr ; Pešek, Luděk ; Šnábl, Pavel ; Bula, Vítězslav
The aim of the modal analysis was to compare and identify the material constants of two proposed mixtures of rubber damping segments of a railway wheel. The modal analysis was carried out in two stages, experimentally and then numerically. The experimental modal analysis was carried on a rubber-suspension wheel for the two proposed rubber types of segment , designated 42809 and 46809. From this dynamic analysis, the natural frequencies and eignemodes of the wheel oscillations were obtained in the frequency bandwidth up to 6.5kHz. The material constants of the rubber were obtained by tuning the material parameters of the rubber segments, i.e. elastic modulus and special proportional damping coefficient, of the 3D FEM model of the railway wheel to the values of natural frequencies and damping ratios of the selected wheel natural vibration modes.
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Influence of Mixing Line Parameters Adjustment on Mixture´s Properties
Smiřický, Jan ; Kučera, František (referee) ; Petrůj, Jaroslav (advisor)
The main goal of this thesis is to set optimal rubber mixture processing parameters in Barum Continental Ltd. Dispersion is one of the most important tire production steps. Although rubber mixing has been researched by several generations of experts, there are still some unexplored influencing variables. The automotive companies are keen on the reduction of emissions and therefore pushes the tire manufactures as they can contribute to emission reduction, as well as the enhancement of tire toughness. Enhancement of tire toughness causes the decreasing of rolling resistance. Higher toughness is exhibited by tires made of rubber filled by surface modified silica. Silica filled mixtures creates a three-dimensional net which is capable to coexist with a net made by vulcanization reaction. Other goals of this thesis are to understand the process and technologies used for mixing rubber mixtures designated for tire production.
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The image of jungle in the novels The Vortex by José Eustasio Rivera and Heart of Darkness by Joseph Conrad
Schürgerová, Johana ; Poláková, Dora (advisor) ; Housková, Anna (referee)
The goal of this bachelor's thesis was to focus on the image of the rainforest in the roman The Vortex (La vorágine) by Jose Eustasio Rivera and then to compare it with the african jungle where is set the novelle Heart of Darkness by Johseph Conrad. The object of exploring were the effects of the environment on the characters,too. We observed changes in their behaviour and of their actions in the wilderness. In the end, we have shown the historical events that went down in history as gross abuses of human rights and, subsequently, we analyzed the motives of exploitation of both man and nature in both works.
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History and present of bungee jumping in the Czech lands
Malimánek, Tomáš ; Kašpar, Ladislav (advisor) ; Jandová, Soňa (referee)
The theses deals with the history of bungee jumping in the Czech lands and describes its current form. The aim is to characterize the development of this phenomenon in the Czech context. The area of interest is broad-spectrum and the content of the work reflects several aspects, including physiological and psychosocial aspects. It also includes a summary and analysis of published publications. All information was consulted with the founder and pioneer of Czech bungee jumping. The conclusions show that since its beginnings, bungee jumping in the Czech context has not changed significantly in its essence, it has integrated into the Czech environment, and that today it occupies its place mainly in recreology. At the same time, there is a lack of publications focusing on the topic. KEYWORDS Bungee jumping, extreme sports, adrenalin 2
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Design of a rubber coupling for railway applications
Blach, Jiří ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
The diploma thesis deals with the design and stress-strain analysis of a flexible coupling composed of individual rubber-textile segments. This concept allows the manufacturer to simplify and unify the production thanks to the ability to use a single segment design for multiple coupling configurations and thus leads to a reduction in costs on the part of the manufacturer. From the consumer side this allows only mechanically or chemically damaged segments to be replaced instead of the entire coupling and saves costs for the potential user. The coupling assembly is primarily designed according to the parameters of intercity electric units and locomotives, however, the individual flexible segments are not limited by this use. When designing a coupling assembly, it is necessary to place requirements primarily on the high safety of all components. The operating mode, in which the relative displacement of the input and output shafts can occur, indicates a relatively wide range of transmitted loads which, if any assembly part is improperly designed, can cause problems leading to temporary putting the entire machine/vehicle out of order. The most critical areas of the assembly include the flexible segments, the bolt connections, the strength of the hubs and the spline joint for torque transfer. Last but not least, the requirements for the non-complex production of components must be taken into account, together with the assembly and maintenance without collision of the components and the necessary tools. In order to verify the above-mentioned requirements, stress-strain analyses are performed simulating the variation of operating load conditions. Due to the reduction of hardware requirements and computational time, together with the absence of experimentally measured data of rubber and PES codes, the flexible segments were modelled at a lower level with a reduced material model favouring the tensile properties of PES cords. However, this reduction provides a more conservative approach, as this use causes higher stresses on the steel components of the assembly. Subsequently, a stress analysis of the splined joint is performed. Due to the absence of specific shaft geometry models of commercial motors and gearboxes, a parallel splines were chosen for this purpose and designed according to the specified maximum torque. The last part of the thesis is focused on verifying the tensile properties of an individual flexible segment.
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On the effect of tempering and storage conditions of rubber parts on final joint cohesion
Jílková, Ingrid ; Kalivoda, Milan (referee) ; Píška, Miroslav (advisor)
This bachelor’s thesis deals with an analysis of waxing phases occurrence on the surface of the technical rubber which is used in the automotive industry. The theoretical part of this thesis deals with a composition and manufacturing of the rubber. It is focused on the composition of rubber compounds and waxes. It explains technical properties, reasons (advantages) of the ingredients in the rubber components. Next, it also clarifies the substance of the wax and its use in relation to rubbers. The theoretical part also clarifies the storage of rubber parts and why is it desirable to identify the wax which is separated on free surfaces of rubber. The practical part deals with a suggestion of the identification methods for the waxes on the surface of rubber. It also presents the comparison of the possibilities of the methods used for the identification of wax and its evaluation.
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Investigation of storage conditions influence on adhesion of rubber bushings
Kvapil, Štěpán ; Muroň, Aleš (referee) ; Kandus, Bohumil (advisor)
The theoretical part of the thesis is focused on research on vulcanization and post-vulcanization, i.e. the production of rubber and the connection of rubber with metal using the latest technologies. This part serves as the theoretical basis for the development of the training base and the experimental part, which are part of the practical part. The training materials are serving for faster and more effective training of new staff and as a comprehensive set of information to the MAT center. The methodology of the manual is described in the main thesis and identical examples from this document are inserted in this thesis too. The experimental part focuses on the adhesion of rubber to the metal surface with subsequent evaluation. The whole problem from the preparation, post-vulcanization, tearing, through measurement to determination of the maximal storage life of sprayed rubber bearings is described.
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The image of jungle in the novels The Vortex by José Eustasio Rivera and Heart of Darkness by Joseph Conrad
Schürgerová, Johana ; Poláková, Dora (advisor) ; Housková, Anna (referee)
The goal of this bachelor's thesis was to focus on the image of the rainforest in the roman The Vortex (La vorágine) by Jose Eustasio Rivera and then to compare it with the african jungle where is set the novelle Heart of Darkness by Johseph Conrad. The object of exploring were the effects of the environment on the characters,too. We observed changes in their behaviour and of their actions in the wilderness. In the end, we have shown the historical events that went down in history as gross abuses of human rights and, subsequently, we analyzed the motives of exploitation of both man and nature in both works.
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Modification of epoxy resin effecting ductility of wood bonds
Hudečková, Petra ; Drochytka, Rostislav (referee) ; Vaněrek, Jan (advisor)
This bachelor thesis is focus on a jointing process of wood parts, the basic kinds of adhesives that are used for wood constructions, and also deals with an important demands on a bonded wood joint. Then there is briefly described an issue of fracture toughness and the ways of epoxy adhesives filling, primarily filling with the rubber, the thermoplastics and other fillers. In the experimental part the reinforcing of epoxy matrix with the different quantity of rubber was carried out. The mixture was prepared by an ultrasound homogenizer. Firstly, the tensile strength test with epoxy samples was carried out. Secondly, the Young modulus was calculated and in the last part the fracture surface was analyzed with the scanning electron microscope.
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