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1
Content available Magnetostatic analysis of a pinch mode magnetorheological valve
Gołdasz J., Sapiński B.
Acta Mechanica et Automatica
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2017
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Vol. 11, no. 3
229--232
EN
The study deals with the pinch mode of magnetorheological (MR) fluids’ operation and its application in MR valves. By applying the principle in MR valves a highly non-uniform magnetic field can be generated in flow channels in such a way to solidify the portion of the material that is the nearest to the flow channel’s walls. This is in contrary to well-known MR flow mode valves. The authors investigate a basic pinch mode valve in several fundamental configurations, and then examine their magnetic circuits through magnetostatic finiteelement (FE) analysis. Flux density contour maps are revealed and basic performance figures calculated and analysed. The FE analysis results yield confidence in that the performance of MR pinch mode devices can be effectively controlled through electromagnetic means.
2
Content available remote Numerical study of a two-way MR mount in squeeze-mode
Gołdasz J., Sapiński B.
Czasopismo Techniczne. Elektrotechnika
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2016
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Y. 113, iss. 2-E
29--40
EN
In the paper, the authors present the results of a numerical study of a magnetorheological (MR) damper prototype operating in the so-called squeeze mode. The analyzed prototype allows achieving a symmetrical response in both directions of piston motion. The authors show the results of magnetostatic analyses of the electro-magnetic circuit of the device and lumped parameter model using calculations of the control circuit and the damping force output.
PL
W artykule przedstawiono wyniki obliczeń prototypowej konstrukcji tłumika z cieczą MR działającej w trybie ściskania. Analizowany prototyp pozwala uzyskać identyczny zakres sił tłumienia w obu kierunkach ruchu. Autorzy prezentują osiągi tłumika oszacowane na podstawie obliczeń polowych oraz obliczeń z wykorzystaniem modelu o parametrach skupionych.
3
Content available Theoretical study of a twin-tube magnetorheological damper concept
Gołdasz J.
Journal of Theoretical and Applied Mechanics
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2015
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Vol. 53 nr 4
885—894
EN
In this study, the author presents a theoretical model of a semi-active magnetorheological (MR) twin-tube damper concept. The model relies on geometric variables and material properties and can be used in engineering and research studies on damper structures. Other non-linear characteristics, namely, the fluid chamber compressibility, fluid inertia, cylinder elasticity, friction, one-way check valves are included into the model as well. The author studies the performance of the damper model as design variables are varied, and the results are analysed and discussed.
4
Content available Application of CFD to modeling of squeeze mode magnetorheological dampers
Gołdasz J., Sapiński B.
Acta Mechanica et Automatica
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2015
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Vol. 9, no. 3
129--134
EN
The so-called squeeze flow involves a magnetorheological (MR) fluid sandwiched between two planar surfaces setting up a flow channel. The height of the channel varies according to a prescribed displacement or force profile. When exposed to a magnetic field of sufficient strength MR fluids develop a yield stress. In squeeze-mode devices the yield stress varies with both the magnetic field magnitude and the channel height. In this paper an unsteady flow model of an MR fluid in squeeze mode is proposed. The model is developed in Ansys Fluent R16. The MR material flow model is based on the apparent viscosity approach. In order to investigate the material's behaviour the authors prepared a model of an idealized squeeze-mode damper in which the fluid flow is enforced by varying the height of the channel. Using mesh animation, the model plate is excited, and as the mesh moves, the fluid is squeezed out of the gap. In the simulations the model is subjected to a range of displacement inputs of frequencies from 10 to 20 Hz, and local yield stress levels up to 30 kPa. The results are presented in the form of time histories of the normal force on the squeezing plate and loops of force vs. displacement (velocity).
5
Content available remote Electro-mechanical analysis of a magnetorheological damper with electrical steel laminations
Gołdasz J.
Przegląd Elektrotechniczny
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2013
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R. 89, nr 2a
8--12
EN
The study outlines the concept of piston for a magnetorheological (MR) damper. The piston configuration that is analyzed in the paper utilizes a core made out of six SiFe laminated stacks having radially projecting arms away from the centre of the core. The coil is then wound around the radially projecting arms. There has been no published data on the performance characteristics of MR dampers with such pistons. Therefore, in the author focuses on a parametric magneto-static study of such a piston configuration followed by calculations of its steady-state force-velocity maps. Damping force calculations were performed using the so-called biplastic Bingham model. The results are presented in the form of magnetic field’s contour maps, averaged flux density levels in the annulus and steady-state force-velocity maps, respectively, two different annular gap sizes in the piston and a range of coil currents from 0 to 5 A.
PL
W artykule przedstawiono koncepcję tłoka amortyzatora samochodowego z cieczą magnetoreologiczną (MR). Analizowana w artykule konfiguracja tłoka zawiera rdzeń, na którym promieniowo rozmieszczono sześć stosów z blachy elektrotechnicznej. Cewka rdzenia nawinięta jest wokół ramion każdego stosu. Opisano zasadę działania takiej konstrukcji amortyzatora. Zgodnie z aktualnym stanem wiedzy autora, do tej pory nie pojawiły się żadne publikacje dotyczące spodziewanych osiągów amortyzatorów MR tego typu. Przedstawiono wyniki obliczeń charakterystyk sił tłumienia takiego amortyzatora, przeprowadzając obliczenia numeryczne rozkładu pola magnetycznego oraz hydrauliczne z wykorzystaniem modelu biplastycznego Binghama. Wyznaczono rozkłady indukcji magnetycznej w tłoku oraz charakterystyki sił tłumienia w funkcji prędkości tłoka dla dwóch różnych wartości szczeliny w tłoku i zakresu prądu cewki od 0 do 5 A.
6
Content available Modelling of amplitude-selective-damping valves
Gołdasz J.
Mechanics and Control
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2011
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Vol. 30, no. 2
60-64
EN
The so-called amplitude-selective-damping (ASD) valving is a relatively new approach for modifying the output of a hydraulic shock absorber. In the automotive industry ASD valves are known to improve isolation from road inputs. During more aggressive maneuvers the systems maintains the performance of a standard (non-ASD) shock absorber. In the paper, the author derives and analyzes a fairly complete state-space model of an exemplary piston-side ASD valve. The model includes key geometric and performance characteristics of the valve. The results are shown in the form of phase plane plots of force-displacement diagrams, respectively, for a twin-tube shock absorber configuration of choice.
PL
W pracy przedstawiono model dwururowego amortyzatora samochodowego z zaworem o charakterystyce zależnej od amplitudy przemieszczenia. Zawór dodatkowy działa równolegle do zaworu głównego tłoka i pozwala na kształtowanie osiągów amortyzatora w zakresie małych przemieszczeń oraz średnich i wysokich częstotliwości wymuszenia. Model zawiera kluczowe zmienne geometryczne i materiałowe uwzględniające podstawowe osiągi zaworu w szerokim paśmie przemieszczeń i częstotliwości. Wyniki obliczeń zaprezentowano na płaszczyźnie fazowej siła-przemieszczenie w zakresie prędkości do 260 mm/s i częstotliwości wymuszenia do 12 Hz.
7
Content available Modeling of magnetorheological mounts in various operation modes
Gołdasz J., Sapiński B.
Acta Mechanica et Automatica
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2011
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Vol. 5, no. 4
29-40
EN
Recent advances in the research of magnetorheological/electrorheological (MR/ER) fluid based devices have indicated the opportunities for smart fluid based devices utilizing more than one operation mode. As such, the purpose of the present research is to draw attention to the existing models of magnetorheological (MR) mounts operating in two of the three fundamental operating modes, namely, the flow mode and the squeeze mode, and to highlight the potential applications of these modes in hydraulic mount applications. Therefore, in the paper the authors focus on recent applications of MR/ER fluids in that domain, and then proceed to summarizing the modeling principles for the two operation modes followed by a finite-element magnetostatic analysis of the mount's magnetic circuit, parameter sensitivity study and exemplary nu-merical simulations of each mode. The simulation results are converted into the frequency domain and presented in the form of dynamic stiffness and damping vs. frequency plots, respectively.
8
High-frequency model of monotube shock absorbers
Gołdasz J.
Modelowanie Inżynierskie
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2010
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T. 8, nr 39
81-88
EN
It has been long recognized that the inertia and compressibility of the fluid have an impact on the dynamic behaviour of semi-active monotube shock absorbers utilizing so-called smart ER/MR fluids at high frequencies of the system operation. Previous studies which dealt with analytical state-space & CFD models of the magnetorheological shock absorber in a monotube configuration indicated that any conventional analytical model is lightly damped and not suitable for dynamic studies above 100-150 Hz. Therefore, in the present paper the author illustrates an analytical model of a monotube shock absorber that is suitable for high-frequency studies. In particular, the study presents a comparison between the CFD results and the new model. Finally, the shock absorber characteristics in the form of Bode plots of amplitude and frequency are presented within a prescribed range of frequencies.
9
Dynamics of a quarter car system with amplitude selective damping
Gołdasz J., Knapczyk M.
Modelowanie Inżynierskie
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2010
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T. 8, nr 39
89-96
EN
An amplitude-selective damping is a phenomenon in hydraulic shock absorbers where a pressure drop is a function of physical displacement even at a constant flow rate. The combination is often claimed to provide less damping for small displacement inputs as well as ordinary ride on vehicles. At the same time the system offers good ride and handling metrics by augmenting the damping force during such vehicle manoeuvres. Therefore, the purpose of this study is to investigate the dynamic performance of a simple two-degree-of-freedom (2DOF) system with an amplitude-selective damping type shock absorber. In the paper the authors derive & analyze a model of the shock absorber on a component level, then study the influence the device has on the suspension behaviour within the prescribed range of frequencies.
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