scholarly journals Magnetorheological Elastomer-Based Variable Stiffness Flexible Coupling for Vibration Isolation.

2021 ◽  
Author(s):  
Thaer Mahmoud Syam ◽  
Ahmed Hegazi ◽  
Asan Muthalif ◽  
Yousif Badri
Keyword(s):  
Magnetic Field ◽  
Torsional Vibration ◽  
Vibration Isolation ◽  
Volume Fraction ◽  
Torsional Rigidity ◽  
Magnetic Field Effect ◽  
Variable Stiffness ◽  
Torsional Stiffness ◽  
Smart Composite Materials ◽  
The Magnetic Field

Magnetorheological elastomers (MRE) are smart composite materials by which their mechanical properties, such as stiffness, are changed under a magnetic field. In this article, the introduction of a variable stiffness coupling (VSC) fitted within a shaft for torsional vibration isolation that would adapt and change its attenuation frequency range is presented. The VSC concept on torsional vibration isolation is tested experimentally. MRE samples with 40% volume fraction are fabricated and manufactured using a 3D mold design and fixed within a coupling in a shaft to investigate the magnetic field effect on the torsional rigidity. Impact hammer test is conducted along with an accelerometer to obtain the transmissibility factor analysis. Results show that the vibration level decreases when the magnetic field increases. The 1st natural frequency of the system happened at 26 Hz and moved to 28 Hz when the applied current increases from 0 mT to 12.38 mT. MRE torsional stiffness increased from 37.4 N.m/rad to 61.6 N.m/rad when the current increased from 0 mT to 12.38 mT. The torsional damping coefficient showed a fluctuation in its variation as the damping effect of MR elastomer is ignored

scholarly journals A new magnetorheological elastomer torsional vibration absorber: structural design and performance test

2021 ◽  
Vol 12 (1) ◽  
pp. 321-332
Author(s):  
Pu Gao ◽  
Hui Liu ◽  
Changle Xiang ◽  
Pengfei Yan ◽  
Taha Mahmoud
Keyword(s):  
Magnetic Field ◽  
Torsional Vibration ◽  
Performance Test ◽  
Magnetic Circuit ◽  
Circuit Simulation ◽  
Variable Stiffness ◽  
Vibration Absorber ◽  
Vibration Exciter ◽  
Magnetorheological Elastomer ◽  
The Magnetic Field

Abstract. The semi-active torsional vibration absorber can effectively reduce the torsional vibration of the power-train system. In this paper, a new type of variable stiffness torsional vibration absorber with a magnetorheological elastomer (MRE) as an intelligent controlling element is designed, and the modal analysis, frequency-tracking scheme, and damping effects have been studied. A transient dynamic simulation is utilized to validate the rationality of the mechanical structure, the magnetic field parameters of the absorber are matched, and the magnetic circuit simulation analysis and the magnetic field supply analysis are carried out to verify the closed magnetic circuit. The principle prototype of the innovative vibration absorber is manufactured, the magnetic field strength of the absorber is tested by a Gauss meter, and the results show the efficacy of magnetizing the vibration absorber with a conductive slip ring by solving the magnetizing problem of the rotating parts of the vibration absorber. A special-purpose test rig with a torsional vibration exciter as a power source has been implemented. A comparative experiment has been carried out to test the frequency shift characteristics and authenticate the vibration-reduction effect of the new MRE torsional vibration absorber.

Magnetic Field Effect on Mixed Convection in Lid-Driven Trapezoidal Cavities Filled With a Cu–Water Nanofluid With an Aiding or Opposing Side Wall

2016 ◽  
Vol 8 (3) ◽  
Author(s):  
Ali J. Chamkha ◽  
Muneer A. Ismael
Keyword(s):  
Magnetic Field ◽  
Mixed Convection ◽  
Volume Fraction ◽  
Magnetic Field Effect ◽  
Side Wall ◽  
Cu Nanoparticles ◽  
Suppression Effect ◽  
Side Walls ◽  
The Right ◽  
The Magnetic Field

The present study investigates mixed convection inside a Cu–water nanofluid filled trapezoidal cavity under the effect of a constant magnetic field. The mixed convection is achieved by the action of lid-driving of the right hot inclined side wall in the aiding or the opposing direction. The left inclined side wall is fixed and kept isothermal at a cold temperature. The horizontal top and bottom walls are fixed and thermally insulated. The magnetic field is imposed horizontally. The problem is formulated using the stream function-vorticity procedure and solved numerically using an efficient upwind finite-difference method. The studied parameters are: the Richardson number Ri = (0.01–10), the Hartman number Ha = (0–100), the volume fraction of Cu nanoparticles φ = (0–0.05), and the inclination angle of side walls Φ = (66 deg, 70 deg, 80 deg). The results have shown that the suppression effect of the magnetic field for the aiding case is greater than that for the opposing case. Meanwhile, the enhancement of the Nusselt number due to the presence of the Cu nanoparticles is greater for opposing lid-driven case.

The Model for Calculation the Hall Effect Parameter

2004 ◽  
Vol 9 (2) ◽  
pp. 129-138
Author(s):  
J. Kleiza ◽  
V. Kleiza
Keyword(s):  
Magnetic Field ◽  
Field Effect ◽  
Magnetic Field Effect ◽  
Mapping Method ◽  
Sample Thickness ◽  
System Of Nonlinear Equations ◽  
Specific Resistivity ◽  
Conformal Mapping Method ◽  
Effect Parameter ◽  
The Magnetic Field

A method for calculating the values of specific resistivity ρ as well as the product µHB of the Hall mobility and magnetic induction on a conductive sample of an arbitrary geometric configuration with two arbitrary fitted current electrodes of nonzero length and has been proposed an grounded. During the experiment, under the constant value U of voltage and in the absence of the magnetic field effect (B = 0) on the sample, the current intensities I(0), IE(0) are measured as well as the mentioned parameters under the effect of magnetic fields B1, B2 (B1 ≠ B2), i.e.: IE(β(i)), I(β(i)), i = 1, 2. It has been proved that under the constant difference of potentials U and sample thickness d, the parameters I(0), IE(0) and IE(β(i)), I(β(i)), i = 1, 2 uniquely determines the values of the product µHB and specific resistivity ρ of the sample. Basing on the conformal mapping method and Hall’s tensor properties, a relation (a system of nonlinear equations) between the above mentioned quantities has been found.

The magnetic field effect on heat-exchange characteristics and MHD resistance of lead-bismuth eutectic flow in the TOKAMAK blanket heat-sink systems

2013 ◽  
Vol 49 (1-2) ◽  
pp. 237-248
Author(s):  
A. V. Beznosov ◽  
O. O. Novozhilova ◽  
S. Yu. Savinov ◽  
M. V. Yarmonov ◽  
R. E. Alekseev
Keyword(s):  
Magnetic Field ◽  
Heat Exchange ◽  
Heat Sink ◽  
Field Effect ◽  
Magnetic Field Effect ◽  
Lead Bismuth Eutectic ◽  
The Magnetic Field

Effects of uniform or non-uniform heating at bottom wall on MHD mixed convection in a porous cavity saturated by nanofluid

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Subramanian Muthukumar ◽  
Selvaraj Sureshkumar ◽  
Arthanari Malleswaran ◽  
Murugan Muthtamilselvan ◽  
Eswari Prem
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Transfer Rate ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Darcy Number ◽  
Bottom Wall ◽  
Uniform Heating ◽  
The Magnetic Field

Abstract A numerical investigation on the effects of uniform and non-uniform heating of bottom wall on mixed convective heat transfer in a square porous chamber filled with nanofluid in the appearance of magnetic field is carried out. Uniform or sinusoidal heat source is fixed at the bottom wall. The top wall moves in either positive or negative direction with a constant cold temperature. The vertical sidewalls are thermally insulated. The finite volume approach based on SIMPLE algorithm is followed for solving the governing equations. The different parameters connected with this study are Richardson number (0.01 ≤ Ri ≤ 100), Darcy number (10−4 ≤ Da ≤ 10−1), Hartmann number (0 ≤ Ha ≤ 70), and the solid volume fraction (0.00 ≤ χ ≤ 0.06). The results are presented graphically in the form of isotherms, streamlines, mid-plane velocities, and Nusselt numbers for the various combinations of the considered parameters. It is observed that the overall heat transfer rate is low at Ri = 100 in the positive direction of lid movement, whereas it is low at Ri = 1 in the negative direction. The average Nusselt number is lowered on growing Hartmann number for all considered moving directions of top wall with non-uniform heating. The low permeability, Da = 10−4 keeps the flow pattern same dominating the magnetic field, whereas magnetic field strongly affects the flow pattern dominating the high Darcy number Da = 10−1. The heat transfer rate increases on enhancing the solid volume fraction regardless of the magnetic field.

Inversion in the magnetic field effect of benzilketyl:SDS radical pair at high fields

1999 ◽  
Vol 305 (1-2) ◽  
pp. 63-70 ◽  
Author(s):  
Ajay Misra ◽  
Mintu Haldar ◽  
Mihir Chowdhury
Keyword(s):  
Magnetic Field ◽  
Field Effect ◽  
Radical Pair ◽  
Magnetic Field Effect ◽  
High Fields ◽  
The Magnetic Field

Exploration of the magnetic field effect on the orientation of Nd2Fe14B crystallites at high temperatures

1996 ◽  
Vol 153 (1-2) ◽  
pp. 224-230 ◽  
Author(s):  
Pierre Courtois ◽  
René Perrier de la Bâthie ◽  
Robert Tournier
Keyword(s):  
Magnetic Field ◽  
High Temperatures ◽  
Field Effect ◽  
Magnetic Field Effect ◽  
The Magnetic Field

scholarly journals Distributed variable stiffness joint assist mechanism based on laminated structure

2021 ◽  
Vol 18 (6) ◽  
pp. 172988142110606
Author(s):  
Zhenquan Fan ◽  
Xiaoyu Wang ◽  
Zijin Wang ◽  
Sijia Gao ◽  
Sheng Lin
Keyword(s):  
Magnetic Field ◽  
Stiffness Matrix ◽  
Variable Stiffness ◽  
Drive Unit ◽  
Joint Power ◽  
Laminated Structure ◽  
Giant Magnetostrictive Material ◽  
In Series ◽  
Field Excitation ◽  
The Magnetic Field

Exoskeleton technology is more and more widely used in military, human rehabilitation, and other fields, but exoskeleton assisting mechanisms have problems such as high quality, concentrated driving sources, and poor flexibility. This article proposes a distributed variable stiffness joint power-assisted mechanism based on a laminated structure, which uses a giant magnetostrictive material as the driving source and the variable stiffness source of the structure. The distributed driving is realized by multiple driving units connected in series and parallel. Firstly, the drive unit stiffness matrix is deduced, and the expression equations of the cascaded total stiffness matrix of the drive module are obtained. After the simulation study, the curve of the stiffness of a single drive unit with a magnetic field and the stiffness of multiple drive units connected in series and parallel are in the absence of the magnetic field. The change curve of the stiffness of the booster module with the number of drive units under the excitation and saturation magnetic field excitation conditions is to achieve the effect of dynamically controlling the structural stiffness of the drive unit by controlling the size of the magnetic field and to obtain a general formula through data fitting. The number of drive units required under a fixed magnetic field excitation can ensure that the error is within 5%. The research results lay the foundation for further analysis of the distributed variable stiffness joint assist technology.

scholarly journals Magnetorheological Fluids Behaviour in Oscillatory Compression Squeeze: Experimental Testing and Analysis

2019 ◽  
Vol 13 (4) ◽  
pp. 221-225
Author(s):  
Wojciech Horak ◽  
Marcin Szczęch ◽  
Bogdan Sapiński
Keyword(s):  
Magnetic Field ◽  
Volume Fraction ◽  
Experimental Testing ◽  
Magnetic Field Gradient ◽  
Particle Volume Fraction ◽  
Excitation Frequency ◽  
Magnetorheological Fluid ◽  
Density Level ◽  
Particle Volume ◽  
The Magnetic Field

Abstract This article deals with experimental testing of magnetorheological fluid (MRF) behaviour in the oscillatory squeeze mode. The authors investigate and analyse the influence of excitation frequency and magnetic field density level on axial force in MRFs that differ in particle volume fraction. The results show that, under certain conditions, the phenomenon of self-sealing can occur as a result of the magnetic field gradient and a vacuum in the working gap of the system.

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