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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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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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Development of control electronics for magnetorheological dampers in Formula Student vehicle
Skřivánek, Vladimír ; Dobossy, Barnabás (referee) ; Adámek, Roman (advisor)
The topic of this bachelor thesis is the design of a control board for magnetorheological dampers. The board has to be able to receive input data from a datalogger over the CAN bus. From these data, it has to calculate the required current using a known control algorithm and has to be able to regulate it by feedback using a PI controller. Furthermore, it should be able to measure the temperature of the magnetorheological fluid in the damper to be able to correct the degradation of the damping force due to increasing temperature. Another part of this work is to test the implementation of this control algorithm and measure the F-v characteristics of the magnetorheological damper for different values of current.
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Design of DH bike fork with magnetorheological damper
Salva, Matúš ; Robenek, Dětřich (referee) ; Strecker, Zbyněk (advisor)
When mountain biking over rough terrain, comfort and sufficient wheel pressure are often the limiting factors. That's why there is an effort to innovate suspension and develop dampers that provide better damping characteristics. The usage of semi-active suspension is one way to achieve the desired improvement over the currently used passive systems. In this work, the aim was to develop a magnetorheological damper that is suitable for implementation in commonly available mountain bike forks and whose damping characteristics allow the use of the Skyhook algorithm. A functional model of an MR damper with a stroke of 240 mm and an outer diameter of 29.5 mm, whose dynamic range is 9.5 at a piston velocity of 0.25 ms-1 and a time response of 17 ms, was developed. The magnetic circuit of the manufactured functional pattern is of 11SMn30. The damper served to verify the functionality of the concept and at the same time its damping characteristics were experimentally verified and compared with the predicted values. Due to the combination of numerical and analytical model, a very good agreement between prediction and experiment was achieved. Hence, an MR damper with a magnetic circuit made of Hiperco/Vacoflux 50 material was subsequently designed with a predicted dynamic range of 9.5 and a time response of less than 10 ms. The resulting total weight of the design is 0.68 kg. This design fully satisfies all requirements. When used in combination with semi-active control using the Skyhook algorithm, it is predicted to improve ride comfort by 28 %. The potential to use the proposed MR damper is with the increasingly widespread electric bicycles mainly due to the higher weight in conjunction. At the same time, however, the possibility of using it on a regular bicycle is not excluded. Semi-active suspension is a new and not yet widely used technology in cycling and has the potential to reach a new range of consumers. Considering all the advantages and disadvantages, it can be concluded that the proposed MR shock absorber allows to improve the rideability of mountain bikes both in terms of ride comfort, wheel traction or in the form of reduced energy expenditure during pedalling due to energy absorption by the suspension.
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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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