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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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Study on kinetic stability of suspension with magnetorheological properties
Vlachová, Kristýna ; Kráčalík, Milan (referee) ; Smilek, Jiří (advisor)
Sedimentation in magnetorheological (MR) fluids is undesirable for many technological applications. For this reason, several ways have been proposed to prevent sedimentation instability. This thesis deals specifically with the addition of a suitable additive. The topic was examined based on available literature and according to it was suggested a procedure for the experimental part. Two types of MR liquids with different composition and preparation method were prepared. The first suspensions included a water-in-oil emulsion as a carrier liquid and Span 80 and Tween 80 as additives. For the second MR fluids, the continuous phase was a blend of bearing oils and the suspension was stabilized with organoclay. In both cases, carbonyl iron particles with a diameter of 1,8–2,3 µm were used. The kinetic stability of the prepared MR fluids was monitored and compared using an analytical centrifuge.
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Study on wear of material in contact with MR fluid
Žáček, Jiří ; Vimmr, Jan (referee) ; Kubík, Michal (advisor)
This paper is focused on MR dampers and its critical parts in term of damper`s durability, which seems to be a piston-rod seals, and it should find an ideal material combination of seal and MR fluid for increasing the damper`s life. The tests were conducted in modified pin-on-flat configuration, which was supposed to be more suitable for laboratory testing. There was tested and compared a suitable material for seals, like PTFE, NBR, SBR of polyurethanes. The article is also focused on MR fluids and its contribution to seal`s wear. The impact of particle concentration, wear of MR fluid and effect of modification of MR fluid was tested. It showed up, that the best material for seal is H-PU95FDA. The effect of particle concentration is negligible on seal`s wear, while effect of modification and wear of MR fluids are significantly higher.
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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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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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Production technology of Magnetorheological fluids
Nováček, Vladislav ; Mazůrek, Ivan (referee) ; Roupec, Jakub (advisor)
The thesis deals with the overview over the current knowledge at the field of magnetorheological (MR) fluids. It includes definition of basic characteristics of MR fluids and technological aspects in production of the most important particles and carrier fluids. The aim of the thesis is to describe technological methods used in MR fluids production that can be used for different purposes at BTU. Finally, the thesis tries to estimate possible ways in MR fluids development in the future.
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Measurement of wear in shock absorber with magnetorheological fluid
Žáček, Jiří ; Strecker, Zbyněk (referee) ; Roupec, Jakub (advisor)
This bachelor thesis deals with measurement of abrasivity of magnetorheological fluids and its effect on hydraulic shock absorber. The abrasion could be measured and evaluated by many ways. The pin on block measurement method has been selected for this test. The pin was moving on a steel block while the whole system was surrounded by magnetorheological fluid. According to results, the lifetime of magnetorheological shock absorber is 4 times shorter than classical damper. Results of this thesis could be helpful in damper construction or in development of new magnetorheological fluids.
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Megnetorheological shockabsorber
Lazar, Jaroslav ; Růžička, Bronislav (referee) ; Mazůrek, Ivan (advisor)
This master's thesis deals with an engineering design of an external reservoir for hydraulic shock absorbers with combined filling of oil and magnetorheological fluid. The first part describes existing designes of magnetorheological shock absorbers and characteristics of magnetorheological fluid. Next part describes a design of an experimental external reservoir and a test of its functionality on a prototype. This is followed by an optimalized engineering design of the experimental external reservoir.
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Hydrodynamic dampers on the principle of magnetic fluid
Přikryl, Matěj ; Fialová, Simona (referee) ; Pochylý, František (advisor)
This diploma thesis covers the topic of magnetic fluids and their utilisation in hydrodynamic dampers. The first part of the work consists of research on the current state of technology in hydraulic dampers with the focus on dampers using magnetorhelogical fluid. This chapter is followed by research on magnetic fluids with regard to their physical properties and mathematical description, which is used for CFD simulation of flow. The second part deals with the computational simulation of the flow of MR liquid in real MR damper in order to determine the damping characteristic and it's comparison with the experimental data.
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Test of remanency in a sport damper in dependence on a material of magnetic circuit
Polášek, Jan ; Kubík, Michal (referee) ; Roupec, Jakub (advisor)
This bachelor’s thesis deals with testing of maximal magnetic induction, remanence and B-H curve of different kinds of steels and application of this knowledge when choosing materials for magnetic circuit of magnetorheological (MR) dampers. The introduction of the thesis is intended to analyse knowledge of magnetorheological fluids and magnetic characteristics of different kinds of materials. Another part of bachelor’s thesis deals with the choice of steels of different chemical composition, heat treatment of steel, testing and comparing with FEM results. The aim of the thesis is also to design a clamping device for testing of magnetic circuit and to describe used measuring instruments and measurement methodology too.
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