This diploma thesis deals with development of a new generation of magnetic circuits of fast magnetoreological (MR) dampers that will not use problematic ferrite materials. To ensure a short response time, eddy currents must be avoided. Using the Finite Element Method, 2 solutions were proposed - the use of soft magnetic composites with high electrical resistance and the cutting of grooves in metallic material. Subsequently, 2 magnetic circuits were produced - one from Sintex SMC prototyping material composite and one from 11SMn30 steel with 48 deep grooves 0,35 mm wide. Both were implemented into the MR damper and tested on a hydraulic pulsator. The results of the experiments were compared with 2 different MR dampers: one with 11SMn30 magnetic circuit without grooves and another with the Epcos N87 ferrite magnetic core. It has been found that both new circuits have ensured an equally short response of the damper force to the change of electric current like ferrite. At the same time, a much larger dynamic range was ensured. Compared to 11SMn30 without grooves, the new circuits provided approximately 7x faster response.

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.

This diploma thesis deals with an engineering design of a fail-safe magnetorheological (MR) damper capable of semi-active control. The first part of the thesis is devoted to the current state of knowledge of fail-safe MR dampers and permanent magnets contained in these dampers. The next part contains an engineering design of a fail-safe MR damper, made using FEM simulations, and its subsequent testing in terms of magnetic and hydraulic properties. Finally, a design of a fail-safe MR damper with fast response time was made and simulated using verified FEM analysis. Fast response time is ensured by limiting the generation of eddy currents in the piston core by grooving.

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.

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.

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.

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.

The thesis deals with design magnetorheological strut of vibration isolation adapter for cosmonautics. For its optimization is necessary to create several virtual models. The dynamic model of the mechanism - the Stewart platform, rheological model for determining the damping force of MR damper and model of the magnetic circuit to guarantee the required intensity in the gap. These models, along with controls models that are primarily concerned with strength calculations, will help with design. Designing using virtual models requires constant monitoring and verification. It is a rather broad topic including eliminate vibration also kinematics, dynamics, hydraulics, pneumatics and last but not least electronics and magnetism. It is necessary to communicate with experts in their field and use their knowledge and experience to create, but also to control of the individual models. The thesis was created in cooperation with Honeywell Aerospace Division (ESA).

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."

Práce se zabývá návrhem magnetoreologické (MR) vzpěry vibroizolačního systému (VIS) pro kosmický nosič. V rešeršní části jsou popsány vybrané VIS a vzpěry těchto systémů, které byly v kosmických nosičích využity v minulosti. Každá z těchto vzpěr obsahující kapalinu byla těsněna pomocí statických těsnění a pružných vlnovců vyrobených z oceli. Důkladněji byla analyzována vzpěra pasivního systému VIS s označením ELVIS, jehož konstrukce se stala inspirací pro tuto práci. Jedná se o tříparametrický systém, v němž je tlumič uložen na pružině, jejíž tuhost přibližně odpovídá objemové tuhosti vlnovců respektive jejímu průmětu do axiálního směru (pressure thrust stiffness). V práci je představena metodika pro stanovení “pressure thrust stiffness” na základě geometrie vlnovce a také uvedeny parametry vlnovce díky kterým je možné měnit poměr mezi axiální a “pressure thrust stiffness” vlnovce. Tento poměr ovlivňuje v dané koncepci vzpěry její dynamické chování a tím i chování celého VIS. Pro predikci dynamického chování vzpěry byl vytvořen multi-body model VIS založeného na Stewartově plošině a detailnější model jediné vzpěry. Simulace provedené v tomto modelu odhalily parametry, které mají vliv na výkonost tlumiče ve VIS: časová odezva a dynamický rozsah. Díky modelu byl určen rozsah těchto parametrů, ve kterých bude zaručena efektivní funkce vzpěry ve VIS, konkrétně: časová odezva: 0-5ms, dynamický rozsah: 5-10. Před finálním návrhem vzpěry byla sestrojena vzpěra experimentální vzpěra, jejíž parametry byly přesně naměřeny a využity pro verifikaci jednotlivých modelů. Poznatky získané během experimentů byly využity při návrhu finální vzpěry. Jeden z nejdůležitějších poznatků byla nutnost náhrady feritového magnetického obvodu s ohledem na jeho křehkost. Proto byl odvozen tvarový přístup k navrhování rychlých magnetických obvodů z oceli s využitím 3D tisku, který byl následně patentován. Navržená vzpěra obsahuje magnetoreologický ventil jehož odezva je predikována na 1.2 ms a dynamický rozsah 10. V závěru práce je představena metodika, díky které byla vzpěra navržena.