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The study of MR fluids sedimentation
Berka, Pavel ; Vimmr, Jan (referee) ; Roupec, Jakub (advisor)
This diploma thesis investigates the accelerated sedimentation of the magnetorheological fuids (MRFs) using centrifuge. Experiments are carried out at room temperature as well as at higher temperatures (40°C, 60°C and 80°C). The development of the new improved measuring device for the sedimentation evaulation is described. Magnetic components of the device were designed using FEM analysis. Newly designed device is verified. To accomplish the experiments at the high temperatures the new heated chamber for experimental centrifuge is designed and constructed. In the next part of the work full experiment of the accelerated sedimentation is performed. At final the empirical model of the sedimetation velocity for various accelerations and temperatures is synthesized.
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Reconstruktion of road simulator.
Stodolák, Michal ; Roupec, Jakub (referee) ; Mazůrek, Ivan (advisor)
This bachelor’s thesis is dealing with reconstruction of drum road simulator, which is placed in laboratory of The Institute of Machine and Industrial Design. The first part is attended to basic dividing of road simulator. The second part contains description and analysis of the current machine. In the next part is an analysis of chosen variation and their construction. The last part of thesis is attended to the lightening of the load wheel in period, when the test doesn’t run.
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Description and Evaluation of Fastener Torque Characteristics of Screw Connection
Větrovec, Ondřej ; Roupec, Jakub (referee) ; Brandejs, Jan (advisor)
This bachelor’s thesis deals with the description and evaluation of the torque characteristics of screw connection in plastic parts in headlight. The evaluation was compared with the same screws from three different suppliers. Compered was the course of torque when screwing. The work also includes analysis of the current state of knowledge in the use of plastics in the automotive industry and joining plastic parts. There is more emphasis on shaping joining screws.
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Durability test of magnetorheological fluid at high temperature
Grygárek, David ; Strecker, Zbyněk (referee) ; Roupec, Jakub (advisor)
This bachelor’s thesis is focused on behaviour of magnetorheological fluid during the durability test. In the first part are described basic properties of MR fluid and is defi-ned parameter LDE (Lifetime Dissipated Energy), which is used for prediction of durability of MR fluid. Primary part of thesis devote to realization of experiment, which measures a part of durability test at 70°C and monitoring the yield stress, vis-cosity and residual magnetism.
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Design of Low-Pressure Piston Rheometer
Lán, Radek ; Strecker, Zbyněk (referee) ; Roupec, Jakub (advisor)
This thesis is focused in design of Low-Pressure Piston Rheometer intended for experimental identifying of magneto-rheologic (MR) liquid properties at long-term load. MR liquid is briefly introduced in the initial part of the thesis. There follows a search related to way of liquids properties measurement and overview of MR dampers which are close to piston rheometers by their construction. MR dampers with through piston-rod have been emphasised. The second part of the thesis is focused on calculation of magnetic circuit of the rheometer throttle leak. The rheometer is designed in the last part of the thesis.
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Design of magnetorheological clutch.
Nováček, Vladislav ; Dočkal, Aleš (referee) ; Roupec, Jakub (advisor)
This thesis deals with the design of the magnetorheological (MR) clutch. The extensive literature research with particular conclusions to each design variant of MR clutches or brakes has been done in the first part of the thesis. The second part of the thesis describes the design of the actual MR clutch based on the results of the analytical calculation of the magnetic circuit. Finally, the experiments verifying the function of the key segments of the clutch, and the whole clutch are summarized in the third part of the thesis.
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Contemporary design of rotary compressors, prevention of their surge
Kopáček, Petr ; Roupec, Jakub (referee) ; Nevrlý, Josef (advisor)
The bachelor’s thesis deals with design of rotary compressors with analyse prevention of their surge. The first part is concerned with description of basic terms, which are important to understanding studied problem. Then, attention is given to literature, from which are gathered needed data. A description of design of rotary compressors aimed at prevention of surge follows. After that, the thesis is focused at antisurge control of rotary compressors, with consideration to Greitzers model.
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Limiting and Degradation Processes of Magnetorheological Suspension Dampers
Roupec, Jakub ; Bauer, František (referee) ; Ondrůšek, Čestmír (referee) ; Dobeš, Petr (referee) ; Mazůrek, Ivan (advisor)
This work deals with the research of degradation of magnetorheological (MR) fluid during long-term loading under conditions that correspond to the real load in the linear MR devices such as dampers. The behaviour of MR fluid is described by a Bingham model of viscoplastic fluid. The parameters of this model are the yield stress and viscosity. Their values are determined by the shear rate from 1 to 2,8104 s-1. Results of durability tests show a significant decrease in viscosity of MR fluid, a gradual increase in yield stress in the off-state and a significant decrease in MR effect. The paper also described the effect of temperature on these parameters and there is also designed a method of non-assembly diagnostic of the MR fluid state in the damper using the "rate of pulsation."
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Studies on Non-Newtonian Behavior in Slit-flow rheometer at Unsteady flow
Halama, Lukáš ; Vimmr, Jan (referee) ; Roupec, Jakub (advisor)
The thesis deals with the description of the unstable flow of non-Newtonian fluid in a slit-flow rheometer, which negatively affects its behaviour. The initiators of unstable fluid flow are the roughness of the rheometer slit walls, the slip on the rheometer walls, and the influence of the inlet and outlet region geometry of the rheometer slit. The work contains methodical procedures for mathematical consideration of individual unstable fluid flow initiators and design of change of slit geometry of slit-flow rheometer. Part of the work is also a comparison of the most commonly used rheological models, derivation of general relations for the creation of the velocity profile of individual rheological models and their subsequent implementation in the rheological application, which significantly simplifies the process of evaluation of measured data when measured on slit-flow rheometer. This application can be used to determine basic parameters in CFD simulations or as a teaching aid.
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Numerical hydraulic model of active zone in magnetorheological damper
Regner, Dominik ; Roupec, Jakub (referee) ; Kubík, Michal (advisor)
This bachelor thesis deals with the comparison of analytic hydraulic model and numerical models of MR damper‘s active zone. Next is the study of the influence of annular gap geometry and rheological properties of MR fluid to damper‘s performance. In the first part, there is the summary of knowledge about MR dampers and used numerical approaches. Next part describes the creation of models and in the final part there is the comparison of these models and validation is completed with data from the real damper. Also, there is an evaluation of results about changes of geometry and rheology.
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