Estimation of Equivalent Permeability in Magnetorheological Fluid Considering Cluster Formation of Particles

2004 ◽  
Vol 71 (2) ◽  
pp. 201-207 ◽  
Author(s):  
Toshihiko Shiraishi ◽  
Shin Morishita ◽  
Henri P. Gavin
Keyword(s):  
Time Evolution ◽  
Magnetic Permeability ◽  
Cluster Formation ◽  
Simulation Method ◽  
Magnetic Flux Density ◽  
Magnetic Characteristics ◽  
The Finite Element Method ◽  
Mr Fluid ◽  
Equivalent Permeability ◽  
Mr Fluids

This paper describes a simulation method for the equivalent magnetic permeability of mangetorheological (MR) fluids considering cluster formation of suspended particles. The cluster formation under a magnetic field is simulated by cellular automata (CA). Simulated cluster structures are qualitatively equivalent to those observed experimentally. Considering this structure, magnetic permeability analysis is conducted on a representative MR fluid by the finite element method. The equivalent permeability in the MR fluid was obtained from the average magnetic flux density and field. The time evolution of the magnetic characteristics of the MR fluid is shown to correspond to the time evolution of cluster formation.

Investigation of Cluster Formation in MR Fluid under Compression Using Ultrasonic Measurement

2014 ◽  
Vol 792 ◽  
pp. 147-152 ◽  
Author(s):  
Ahmad Isnikurniawan ◽  
Yasuhiro Fujita ◽  
Sachio Tanimoto ◽  
Tatsuo Sawada
Keyword(s):  
Magnetic Flux ◽  
Propagation Velocity ◽  
Cluster Formation ◽  
Ultrasonic Measurement ◽  
Magnetic Flux Density ◽  
Velocity Change ◽  
Mr Fluid ◽  
Mr Fluids ◽  
Measurement Results ◽  
Ultrasonic Propagation

This paper reports measurement results of ultrasonic propagation velocity in MR fluid under compression. Experiments were conducted by applying different pressures in MR fluid at constant magnetic flux density. At low magnetic flux densities (100 and 200 mT), the ultrasonic propagation velocity in MR fluids changes when subjected to pressure. This change is related to cluster formation in MR fluid. The ultrasonic propagation velocity change is smaller when higher pressures are applied, indicating that cluster size in MR fluid becomes thinner under higher pressures. However, at higher magnetic flux densities (300 and 400 mT), ultrasonic propagation velocities under different pressures are nearly similar. These results indicate that at higher magnetic flux densities, pressures do not affect cluster formation in MR fluids.

EVALUATIONS OF CLUSTER STRUCTURE AND MAGNETO-RHEOLOGY OF MR SUSPENSIONS

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1437-1442 ◽  
Author(s):  
HIDEYA NISHIYAMA ◽  
KAZUNARI KATAGIRI ◽  
KATSUHISA HAMADA ◽  
KAZUTO KIKUCHI ◽  
KATSUHIKO HATA ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Cluster Formation ◽  
Cluster Structure ◽  
Mr Damper ◽  
Magnetic Flux Density ◽  
Equivalent Damping ◽  
Damping Characteristics ◽  
Mr Fluids ◽  
Equivalent Damping Coefficient ◽  
Particle Shapes

In the present study, we sysnthesize two types of MR fluids with different particle shapes and sizes. The magnetic functions are evaluated circulatingly by the analysis of cluster formation, rheological properties in the applied magnetic field and damping characteristics in the MR damper, comparing with those of commercial MR fluids. Final objective is to provide the fundamental data for the development of newly advanced MR fluids. The main topics consist of geographycal cluster formation depending on particle shapes and sizes, relating to the apparent viscosity and yield stress with magnetic flux density and further equivalent damping coefficient of two newly sysnthesised MR fluids comparing with those of LORD MR fluid.

B&W IRON

Alloy Digest ◽  
1968 ◽  
Vol 17 (8) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Carbon Steel ◽  
Physical Properties ◽  
Magnetic Permeability ◽  
Electric Motor ◽  
Low Carbon Steel ◽  
Heat Treating ◽  
Magnetic Characteristics ◽  
Low Carbon ◽  
High Magnetic Permeability

Abstract B and W IRON is a thoroughly killed, low carbon steel having a combination of ductility, toughness and high magnetic permeability. It is recommended for applications where good magnetic characteristics are of primary significance, such as in the manufacture of electric motor and generator housings. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Fe-35. Producer or source: Babcock & Wilcox Company.

Magnetorheological Damping of Fragment Barrier Suspension Systems

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Kwon Joong Son ◽  
Eric P. Fahrenthold
Keyword(s):  
Ballistic Performance ◽  
Mr Fluid ◽  
Suspension Systems ◽  
Mr Fluids ◽  
Ballistic Protection ◽  
Protection Systems ◽  
Fluid Damping ◽  
Magnetorheological Damping ◽  
Impact Experiments ◽  
Very High

Magnetorheological (MR) fluids, well established as components of a variety of suspension systems, may offer opportunities to improve the performance of fabric ballistic protection systems, which typically do not incorporate significant energy dissipation mechanisms. A series of ballistic impact experiments has been conducted to investigate the potential of MR fluid damped fabric suspension systems to improve upon current fabric barrier designs. The results indicate that for the simple fabric suspension systems tested, MR fluid damping does not improve upon the very high weight specific ballistic performance of state of the art aramid fibers.

scholarly journals Squeezing Force of the Magnetorheological Fluid Isolating Damper for Centrifugal Fan in Nuclear Power Plant

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Jin Huang ◽  
Ping Wang ◽  
Guochao Wang
Keyword(s):  
Nuclear Power ◽  
Theoretical Foundation ◽  
Fluid Dynamic ◽  
Flow Behavior ◽  
Magnetorheological Fluid ◽  
Centrifugal Fan ◽  
Parallel Channel ◽  
Mr Fluid ◽  
Mr Fluids ◽  
Control Devices

Magnetorheological (MR) disk-type isolating dampers are the semi-active control devices that use MR fluids to produce controllable squeezing force. In this paper, the analytical endeavor into the fluid dynamic modeling of an MR isolating damper is reported. The velocity and pressure distribution of an MR fluid operating in an axisymmetric squeeze model are analytically solved using a biviscosity constitutive model. Analytical solutions for the flow behavior of MR fluid flowing through the parallel channel are obtained. The equation for the squeezing force is derived to provide the theoretical foundation for the design of the isolating damper. The result shows that with the increase of the applied magnetic field strength, the squeezing force is increased.

Calculation and Verification of Magnetic Field Parameters in Axial Active Magnetic Bearing

2014 ◽  
Vol 214 ◽  
pp. 143-150
Author(s):  
Piotr Graca
Keyword(s):  
Magnetic Field ◽  
Finite Element Method ◽  
Magnetic Force ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Magnetic Flux Density ◽  
Two Dimensional ◽  
The Finite Element Method ◽  
Magnetic Field Computation

The paper presents numerical modeling of an Axial Active Magnetic Bearing (AAMB) based on two-dimensional (2D) magnetic field computation. The calculations, assisted by the Finite Element Method (FEM), have focused on the determination of the magnetic flux density and the magnetic force. Obtained magnetic field parameters were then measured and verified on a physical model.

Internal Organizational Measurement for Control of Magnetorheological Fluid Properties

2006 ◽  
Vol 129 (4) ◽  
pp. 423-428 ◽  
Author(s):  
John R. Lloyd ◽  
Miquel O. Hayesmichel ◽  
Clark J. Radcliffe
Keyword(s):  
Magnetic Field ◽  
Physical Properties ◽  
High Sensitivity ◽  
Time Varying ◽  
Measurable Effect ◽  
Mr Fluid ◽  
Fluid State ◽  
Mr Fluids ◽  
Fluid Properties ◽  
Field Excitation

Magnetorheological (MR) fluids change their physical properties when subjected to a magnetic field. As this change occurs, the specific values of the physical properties are a function of the fluid’s time-varying organization state. This results in a nonlinear, hysteretic, time-varying fluid property response to direct magnetic field excitation. Permeability, resistivity and permittivity changes of MR fluid were investigated and their suitability to indicate the organizational state of the fluid, and thus other transport properties, was determined. High sensitivity of permittivity and resistivity to particle organization and applied field was studied experimentally. The measurable effect of these material properties can be used to implement an MR fluid state sensor.

scholarly journals Material Characterization of a Magnetorheological Fluid Subjected to Long-Term Operation in Damper

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2195 ◽  
Author(s):  
Dewi Utami ◽  
Ubaidillah ◽  
Saiful Mazlan ◽  
Fitrian Imaduddin ◽  
Nur Nordin ◽  
...  
Keyword(s):  
Dynamic Testing ◽  
Testing Machine ◽  
Morphological Observation ◽  
Magnetic Flux Density ◽  
Damping Force ◽  
Stroke Length ◽  
Mr Fluid ◽  
Term Operation ◽  
Operating Cycles

This paper investigates the field-dependent rheological properties of magnetorheological (MR) fluid used to fill in MR dampers after long-term cyclic operation. For testing purposes, a meandering MR valve was customized to create a double-ended MR damper in which MR fluid flowed inside the valve due to the magnetic flux density. The test was conducted for 170,000 cycles using a fatigue dynamic testing machine which has 20 mm of stroke length and 0.4 Hz of frequency. Firstly, the damping force was investigated as the number of operating cycles increased. Secondly, the change in viscosity of the MR fluid was identified as in-use thickening (IUT). Finally, the morphological observation of MR particles was undertaken before and after the long-term operation. From these tests, it was demonstrated that the damping force increased as the number of operating cycles increases, both when the damper is turn on (on-state) and off (off-state). It is also observed that the particle size and shape changed due to the long operation, showing irregular particles.

Effect of Internal Pressure on Flow Properties of Magnetorheological Fluids

2011 ◽  
Author(s):  
Andrea Spaggiari ◽  
Eugenio Dragoni
Keyword(s):  
Internal Pressure ◽  
System Design ◽  
Flow Mode ◽  
Shear Mode ◽  
Mr Fluid ◽  
Mr Fluids ◽  
Experimental Apparatus ◽  
Gear Pumps ◽  
Strengthen Effect ◽  
Hydraulic System Design

Magnetorheological (MR) fluids have a lot of applications in the industrial world, but sometimes their properties are not performing enough to meet system requirements. It has been found that in shear mode MR fluids exhibits a pressure dependency called squeeze strengthen effect. Since a lot of MR fluid based devices work in flow mode (i.e. dampers) this paper investigates the behaviour in flow mode under pressure. The system design is articulated in three steps: hydraulic system design, magnetic circuit design and design of experiment. The experimental apparatus is a cylinder in which a translating piston displaces the fluid without the use of standard gear pumps, incompatible with MR fluids. The experimental apparatus measures the MR fluid yield stress as a function of pressure and magnetic field allowing the yield shear stress to be calculated. A statistical analysis of the results shows that the squeeze strengthen effect is present in flow mode as well and the presence of internal pressure is able to enhance the performance of MR fluid by nearly ten times.

scholarly journals Coupled wave-equation and eddy-current model for modelling and measuring propagating stress-waves

2015 ◽  
Vol 64 (2) ◽  
pp. 215-226
Author(s):  
Tommi Peussa ◽  
Anouar Belahcen
Keyword(s):  
Flux Density ◽  
Eddy Current ◽  
Current Model ◽  
Wave Model ◽  
Magnetic Flux Density ◽  
The Finite Element Method ◽  
Coupled Models ◽  
Steel Bar ◽  
Measured Stress ◽  
Coupled Wave

AbstractThe coupling of the propagating stress wave with the eddy current model is presented. The applied stress produces magnetization in the sample that can be measured outside the sample by measuring the resulting magnetic flux density. The stress and flux density measurements are made on a mechanically excited steel bar. The problem is modelled with the finite element method for both the propagating wave and the eddy current. Three aspects are considered: eddy current model using magnetization from the measurements, coupled wave and eddy current models, and coupled different dimensions in the wave model. The measured stress can be reproduced from the measured flux density by modelling. The coupled models work both for stress and flux couplings as well as for the different dimensionality couplings.

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