Exploiting dynamic magnetic fields for new magnetorheological fluid damping capability

2020 ◽  
Author(s):  
Christian G. Vazquez ◽  
Jeffrey L. Kauffman
Keyword(s):  
Magnetic Fields ◽  
Magnetorheological Fluid ◽  
Fluid Damping ◽  
Damping Capability

Influence of Permanent Magnets Installation Approach on the Torque of а Magneto-Rheological Disk Brake

2021 ◽  
Vol 105 ◽  
pp. 184-193
Author(s):  
Ilya Aleksandrovich Frolov ◽  
Andrei Aleksandrovich Vorotnikov ◽  
Semyon Viktorovich Bushuev ◽  
Elena Alekseevna Melnichenko ◽  
Yuri Viktorovich Poduraev
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Materials ◽  
Permanent Magnets ◽  
Magnetorheological Fluid ◽  
Simulation Modelling ◽  
Disc Brake ◽  
Large Area ◽  
Braking Torque ◽  
The Magnetic Field

Magnetorheological braking devices function due to the organization of domain structures between liquid and solid magnetic materials under the action of an electromagnetic or magnetic field. The disc is most widely used as a rotating braking element that made of a solid magnetic material due to the large area of contact with a magnetorheological fluid. Many factors affect the braking characteristics of the magnetorheological disc brake. Specifically, the value of the magnetic field and how the field is distributed across the work element is significantly affected at the braking torque. There are different ways to generate a magnetic field. In this study, the method of installation of permanent magnets into the construction, allowing to increase the braking torque of the magnetorheological disc brake is proposed. Simulation modelling showing the distribution of the magnetic field across the disk depending on the installation of permanent magnets with different pole orientations were carried out. The model takes into account the possibility of increasing the gap between solid magnetic materials of the structure, inside them which the magnetorheological fluid is placed. Comparative estimation of the distribution of the magnetic fields depending on the chosen method of installation of permanent magnets with different orientations of their poles is carried out. Further research is planned to focus on a comparative assessment of the distribution of magnetic fields depending on the selected material of the braking chamber.

Fabrication and characterization of highly controllable magnetorheological material in compression mode

2020 ◽  
Vol 31 (14) ◽  
pp. 1641-1661 ◽  
Author(s):  
Amin Fereidooni ◽  
Afonso Martins ◽  
Viresh Wickramasinghe ◽  
Afzal Suleman
Keyword(s):  
Magnetic Fields ◽  
Loss Factor ◽  
Magnetorheological Fluid ◽  
Loading Frequency ◽  
Magnetorheological Elastomer ◽  
Magnetorheological Elastomers ◽  
Equivalent Damping ◽  
Magnetorheological Effect ◽  
Equivalent Damping Coefficient

This article is focused on the development and characterization of highly controllable magnetorheological materials for stiffness and damping control in semi-active control applications. Two types of magnetorheological materials are developed in-house: magnetorheological elastomer with soft base elastomer, and magnetorheological fluid encapsulated in regular elastomer, namely magnetorheological fluid-elastomer. In both cases of magnetorheological elastomers and magnetorheological fluid-elastomers, the samples are evaluated using in-house-developed shear and compression test rigs, which are equipped with electromagnets and Hall effect sensors for measuring the magnetic field. These features provide the capability to precisely control a wide range of magnetic fields during the experiments. In the case of magnetorheological elastomers, the experimental results of the in-house magnetorheological elastomers are compared with commercially available counterparts made of hard base elastomer. It is shown that the controllability of the material, that is, the relative magnetorheological effect, is significantly improved in the case of magnetorheological elastomer with soft base elastomer. In addition to various magnetic fields, the samples are subjected to a range of loading amplitudes and frequencies. A general trend is observed where the frequency and strain amplitude cause an opposite effect on both the shear and compressive moduli: the increase in frequency gives rise to a higher value of modulus whereas the increase in amplitude reduces the modulus. Furthermore, the effect of bonding on the performance of the magnetorheological elastomers in compression mode is evaluated and the results indicate a significant increase in the modulus and decrease in the loss factor. In all the cases, however, the change of loss factor does not exhibit a predictable trend as a function of magnetic fields. In order to investigate a magnetorheological-based solution for controlling the damping of a semi-active system, magnetorheological fluid-elastomer samples are made in-house. These samples are fabricated using three different iron concentrations, and are tested in compression (squeeze) mode. The results of these experiments confirm that the equivalent damping coefficient of the material rises with the increase in magnetic field, and this effect becomes stronger as the iron concentration of magnetorheological fluids increases. It is also demonstrated that the magnetorheological effect is highly dependent on the loading frequency and amplitude, where the equivalent damping coefficient decreases with the increase in loading frequency and amplitude. In all the aforementioned cases, the stiffness of magnetorheological fluid-elastomers exhibits minor changes, which offers the in-house-developed magnetorheological fluid-elastomers as a damping only control option, a development that is different from the magnetorheological fluid-elastomers reported in the literature.

Trends in acoustic properties of iron particle seeded auxetic polyurethane foam

2004 ◽  
Vol 218 (2) ◽  
pp. 241-244 ◽  
Author(s):  
F Scarpa ◽  
W A Bullough ◽  
P Lumley
Keyword(s):  
Magnetic Fields ◽  
Iron Particle ◽  
Magnetorheological Fluid ◽  
Acoustic Properties ◽  
Absorption Characteristic ◽  
Frequency Bandwidth ◽  
Iron Particles ◽  
Constant Intensity ◽  
Acoustic Absorption Coefficient ◽  
Flexible Foam

The sound absorption characteristic of a clean, open-cell configuration, typical polyurethane flexible foam is shown against that of an auxetic foam made from it, and this same foam after it has been seeded with a magnetorheological fluid (then dried), having 2–5 μm carbonyl iron particles and subjected to zero, weak and concentrated magnetic fields in an acoustic impedance tube facility. The resultant foam indicates the capability of shifting the peak acoustic absorption coefficient within a given frequency bandwidth when constant intensity magnetic fields are applied.

Research on Rotary Disc-Type MRF Dampers with Nonhomogeneous Magnetic Fields

2008 ◽  
Vol 392-394 ◽  
pp. 497-503 ◽  
Author(s):  
Zhi Cui ◽  
Di Zheng
Keyword(s):  
Magnetic Field ◽  
Shear Rate ◽  
Magnetic Fields ◽  
Magnetorheological Fluid ◽  
Test Stand ◽  
Steady Shear ◽  
Experimental Results ◽  
Magnetic Resistance ◽  
Damping Torque ◽  
The Impact

In this paper, based on the analysis of the damping torque of rotary disc-type magnetorheological fluid (MRF) damper, a new kind of MRF disc-type damper is proposed. The working disc of the new kind of damper has a wedged shape that results in variable working clearances, and hence a nonhomogeneous magnetic field is produced. The magnetic resistance of the MRF filled in the variable clearance is analyzed and the impact of the produced nonhomogeneous magnetic field on the damping torque of the damper is studied. Experiments are conducted and the damper performance under steady shear rate is evaluated with an author-designed test stand. The experimental results show that under the same exciting current and other conditions the output damping torque produced by the MRF of the new kind of damper is much greater than that of the ordinary dampers with parallel disc surfaces and constant working clearance.

Compressive and tensive characteristics of magnetorheological fluid under magnetic fields

2011 ◽  
Vol 19 (4) ◽  
pp. 850-856
Author(s):  
王鸿云 WANG Hong-yun ◽  
高春甫 GAO Chun-fu ◽  
阚君武 KAN Jun-wu ◽  
李泳鲜 LI Yong-xian ◽  
王笑 WANG Xiao
Keyword(s):  
Magnetic Fields ◽  
Magnetorheological Fluid

scholarly journals Field responsive mechanical metamaterials

2018 ◽  
Vol 4 (12) ◽  
pp. eaau6419 ◽  
Author(s):  
Julie A. Jackson ◽  
Mark C. Messner ◽  
Nikola A. Dudukovic ◽  
William L. Smith ◽  
Logan Bekker ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Environmental Conditions ◽  
Dynamic Control ◽  
Magnetorheological Fluid ◽  
Complex Structures ◽  
New Class ◽  
Mechanical Metamaterials ◽  
Application Requirements ◽  
Careful Design ◽  
Selection Of

Typically, mechanical metamaterial properties are programmed and set when the architecture is designed and constructed, and do not change in response to shifting environmental conditions or application requirements. We present a new class of architected materials called field responsive mechanical metamaterials (FRMMs) that exhibit dynamic control and on-the-fly tunability enabled by careful design and selection of both material composition and architecture. To demonstrate the FRMM concept, we print complex structures composed of polymeric tubes infilled with magnetorheological fluid suspensions. Modulating remotely applied magnetic fields results in rapid, reversible, and sizable changes of the effective stiffness of our metamaterial motifs.

Finite Element Analysis of Electromagnetic Device in Magnetorheological Fluid Brake

2012 ◽  
Vol 268-270 ◽  
pp. 1448-1452
Author(s):  
Guang Jie Xiong ◽  
Ling Li
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Magnetic Fields ◽  
Electromagnetic Fields ◽  
Magnetorheological Fluid ◽  
Air Gap ◽  
Element Analysis ◽  
Braking Performance ◽  
Optimum Parameters ◽  
Braking Torque

Magnetorheological fluid (MRF) Brake is a newly-developed intelligent brake in which traditional mechanical brake friction pairs are replaced by MRF materials and the electromagnetism devices are very important components. The controllable magnetic fields are generated by electromagnetism devices which can make MRF materials create related braking torque to control the braking performance of the MRF Brake. In this paper, the electromagnetism device consists of several coil sets which can generate electromagnetic fields for MRF Brake. By using finite element analysis, the magnetic fields generated by electromagnetism devices are compared analytically under the different conditions, and then the optimum parameters are obtained such as coil arrangements, excitation currents and air gap distances and etc. All these evidences are helpful to design the structure of electromagnetism devices in MRF Brake.

Calculated Coronal Magnetic Fields and Their Comparison with the Coronal Structures as Observed during Five Solar Eclipses

1994 ◽  
Vol 144 ◽  
pp. 559-564
Author(s):  
P. Ambrož ◽  
J. Sýkora
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Coronal Magnetic Field ◽  
Coronal Magnetic Fields ◽  
Solar Eclipses ◽  
Coronal Structures

AbstractWe were successful in observing the solar corona during five solar eclipses (1973-1991). For the eclipse days the coronal magnetic field was calculated by extrapolation from the photosphere. Comparison of the observed and calculated coronal structures is carried out and some peculiarities of this comparison, related to the different phases of the solar cycle, are presented.

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