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Integration of stroke sensor into the front bike fork
Pešout, Richard ; Jeniš, Filip (referee) ; Strecker, Zbyněk (advisor)
This bachelor's thesis deals with the design of the installation of the iC-MHL200 sensor in the front suspension fork of a bike, where it will measure the stroke in order to control a magnetorological damper. The thesis first describes selected suspension systems, currently available systems enabling the measurement of bike fork lift and the iC-MHL200 sensor itself. Furthermore, the thesis deals with the design and production of a test holder, the sensor test and its results. Using the results, the installation design itself was subsequently created. During the design, it was necessary to overcome several obstacles, which was achieved with certain compromises and the goal of the thesis was fulfilled. This installation will allow further, more accurate testing of the sensor and later also the control of MR dampers with an affordable but accurate sensor.
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Magnetorheological shock absorber with short response time for train bogie
Šebesta, Karel ; Špalek, Petr (referee) ; Kubík, Michal (advisor)
The diploma thesis deals with the design of a magnetorheological damper with a short response time of the damping force for the bogie of a rail vehicle. The largest component, which slows down the response, is the eddy currents generated in the piston group of the MR damper. A rapid onset of damping force is achieved by using a shape approach in magnetic circuit design. The shape approach increases the distance that the eddy currents must travel, and therefore it helps to reduce them. The shape approach is realized by grooving the core and the shell of the MR damper. The proposed fast version of the MR damper is measured on a hydraulic pulsator and its results show a sufficient time response of the damping force. This response does not exceed 8 ms for the primary onset of the damping force. The new fast design of the MR damper combines the greatest advantages of the technology and enables to meet new requirements for damping elements in the rolling stock chassis.
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Design of semiactive seat suspension for agricultural machines
Zindulka, Martin ; Čížek, Petr (referee) ; Strecker, Zbyněk (advisor)
The thesis deals with design of a semiactive seat suspension system for an agriculture machines and design of dynamic model of the system, which includes real parameters of a magnetorheological (MR) damper. The dynamic model is a single degree of freedom model and it is made in program Matlab. In the model, response time of the MR damper and three control algorithms are implemented (two-state Skyhook, Skyhook linear approximation damper control and Acceleration Driven Damper control). Based on the results of the simulations, the damping characteristics are defined, and the MR damper is modified to achieve fast response time. A test seat is designed to test transmission of vibrations to the driver. The simulation results provide a comparison of efficiency of the seat suspension depending on the response time and control algorithm, as well as a comparison with a passive suspension system. On the designed test seat with MR damper with a fast response time, the vibration transmission is reduced up to 25 % compared with the best passive seat suspension setup.
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Adaptive control of magnetorheological dampers
Míša, Jiří ; Porteš, Petr (referee) ; Zháňal, Lubor (advisor)
The topic of this master´s thesis is the design of adaptive damping algorithm for the prototype magnetorheological dampers, which are used for Formula Student vehicle. The prime output is the development and optimization of the control algorithm which included usage of the MBS software and real data from race track. Temperature compensation to supress the effect of dynamic viscosity of magnetorheological fluid due to the increase in operating temperature and testing of the vertical dynamic of the car on 4 - post test rig was realized as well. The main goal was to obtain better control of the car in transient situations and increase usability of tires via changes in damping based on actual conditions and status of the vehicle.
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Design of magnetorheological damper with asymmetric velocity characteristic
Válek, Josef ; Macháček, Ondřej (referee) ; Kubík, Michal (advisor)
This thesis aims to find optimal solution for magnetorheological damper with asymmetric force-velocity behaviour. Magnetorheological dampers represent a promising direction in the development of vibration dampers, mainly due to their adjustable damping, that depends on electric current. The asymmetric force-velocity behaviour (characteristic) then means difference while compressing or expanding damper and can be achieved by valves. Valves can be solved in mechanical, hydraulic, magnetic, electric way. This bachelor´s thesis evaluates these four ways of solution and develops conceptual solutions for their possible application. One conceptual solution is then elaborated in detail. Chosen mechanical solution with movable plate was verified by calculations and experiment. Experiments confirmed the applicability of a mechanical valve in magnetorheological systems.
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Reconstruction of undetachable LORD MR damper
Lochman, Vít ; Macháček, Ondřej (referee) ; Mazůrek, Ivan (advisor)
The bachelor´s thesis deals with the design and the realization of the modification of the non-demountable magnetorheological damper LORD, which has gained an atypical Fv characteristic in the course of time. The first part of the thesis deals with the operation of the magnetorheological liquid and the various design variants of the magnetorheological dampers. The practical part is devoted to the reverse engineering and the design of the damper modification itself. The complete drawing documentation of the original and the modified damper is included in this work.
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Design of fast magnetorheological damper piston group using selective laser melting technology
Vítek, Petr ; Růžička, Bronislav (referee) ; Strecker, Zbyněk (advisor)
The diploma thesis deals with the development of the magnetic circuit of Magnetoreological (MR) dampers with a short time response. To achieve a short response time, a shape approach was chosen whereby the geometry of the magnetic circuit was chosen to significantly eliminate the occurrence of eddy currents. The influence of structures on magnetic properties was first examined on a simpler toroidal core and then the optimization was subjected to the magnetic circuit of the MR damper itself. Geometry optimization was done using FEM simulations. The resulting geometry was made of pure iron using Selective Laser Melting technology (SLM). In addition, a MR damper was completed and its properties on air and with MR fluid were measured, which were then compared with previously developed rapid MR dampers. It has been found that the newly designed magnetic circuit achieves similar time responses as all other compared fast MR dampers and reaches a higher dynamic range than most of the compared variants. The proposed magnetic circuit also has a significantly reduced weight.
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Magnetorheological Suspension Damper for Space Application
Kubík, Michal ; Porteš, Petr (referee) ; dr hab. inż. Janusz Gołdasz, prof. PK (referee) ; Mazůrek, Ivan (advisor)
Disertační se práce se zabývala vývojem magnetoreologického (MR) tlumiče odpružení pro kosmonautiku. Dle současného stavu poznání jsou důležitými parametry pro semi-aktivně řízený tlumič pro kosmonautiku hermetické oddělení pracovní kapaliny od zbytku nosiče a krátká časová odezva tlumícího elementu. Těmto požadavkům vyhovuje magnetoreologický tlumič s vlnovcovou jednotkou. Magnetický obvod MR tlumiče pro kosmonautiku byl vyroben z feritového materiálu, který umožnil výrazně snížit časovou odezvu. Hermetičnost byla zajištěna použitím vlnovcové jednotky. Konstrukce takového typu tlumiče ovšem přináší celou řadu problémů. Vyvinutý MR tlumič s feritovým magnetickým obvodem dosahoval časové odezvy 4.1 ms a dynamického rozsahu 8. Během konstrukčních prací na MR tlumiči pro kosmonautiku byly hledány nové metody pro konstrukci semi-aktivně řízeného MR tlumiče s krátkou časovou odezvou. Konkrétně se jednalo o metodu eliminace vířivých proudů v magnetickém obvodu MR tlumiče, magnetostatický a transietní magnetický model, CFD model obtokové štěrbiny, hydraulický model MR tlumiče a jejich experimentální verifikace. Tyto nové metody umožní konstrukci MR tlumiče pro kosmonautiku lehčí, s nižší časovou odezvou a vyšším dynamickým rozsahem.
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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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