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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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Design of low-pressure magnetorheological damper
Mareš, Jan ; Žáček, Jiří (referee) ; Kubík, Michal (advisor)
This bachelor thesis deals with the problem of the limited lifetime of sealing elements inside high-pressure magnetorheological dampers. The lifetime could be extended by the low-pressure damper design, which is also the aim of this thesis. The proposed design achieves low-pressure operation thanks to the MR foot valve inserted between the damping piston and floating piston of the air chamber. This foot valve also contains a blow-off check valve. For simplicity and to reduce the upfront costs of the testing prototype, the damper was designed by modifying an existing single-tube high-pressure MR damper available at FSI VUT. The contribution of this thesis is the experimental evaluation of check valve function in MR fluid. Valve exhibits asymmetrical behaviour and closes rapidly. The main outcome is the design of a low-pressure single-tube MR damper. It is expected that operation at lower pressures will extend the lifetime of sealing elements which may lead to broader implementation of MR dampers.
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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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Suppression of recoil in military equipment
Novák, Ondřej ; Žáček, Jiří (referee) ; Klapka, Milan (advisor)
The bachelor´s thesis focuses on dampening the recoil force generated by gunshots in military technology. For this purpose, several methods are currently used, which however limit the possible capabilities of firearms with respect to their accuracy and fire rate effective while being inadaptable to variations in the firing cycle. The goal of this thesis is therefore the compilation of currently used methods and subsequent selection of areas where these methods could be substituted or amended by applying magnetorheological technology. In the first phase a research study was carried out describing the technical solutions currently in use for recoil dampening. Approximate values of recoil brake forces and energies for a commonly used weapon system was also included. In the discussion part of the thesis, the research was then evaluated with respect to the possible application of magnetorheological dampening elements. The main areas suitable for the use of this technology are large-caliber cannons and automatic cannons, in which their use could improve their accuracy and increase the controllable rate of fire while limiting the load on the carriages of these weapons. Based on this thesis, further research may be carried out, focusing on a comprehensive analysis and modelling of magnetorheological buffer use in of the mentioned areas.
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Design of low-pressure magnetorheological damper
Mareš, Jan ; Žáček, Jiří (referee) ; Kubík, Michal (advisor)
This bachelor thesis deals with the problem of the limited lifetime of sealing elements inside high-pressure magnetorheological dampers. The lifetime could be extended by the low-pressure damper design, which is also the aim of this thesis. The proposed design achieves low-pressure operation thanks to the MR foot valve inserted between the damping piston and floating piston of the air chamber. This foot valve also contains a blow-off check valve. For simplicity and to reduce the upfront costs of the testing prototype, the damper was designed by modifying an existing single-tube high-pressure MR damper available at FSI VUT. The contribution of this thesis is the experimental evaluation of check valve function in MR fluid. Valve exhibits asymmetrical behaviour and closes rapidly. The main outcome is the design of a low-pressure single-tube MR damper. It is expected that operation at lower pressures will extend the lifetime of sealing elements which may lead to broader implementation of MR dampers.
|
|
|
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.
|
|
|
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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