scholarly journals Physical Properties and Damping Characteristics of MR Fluids in Low Magnetic Fields.

2000 ◽  
Vol 66 (646) ◽  
pp. 1372-1376
Author(s):  
Tadamasa OYAMA ◽  
Toyohisa FUJITA ◽  
Hideya NISHIYAMA
Keyword(s):  
Magnetic Fields ◽  
Physical Properties ◽  
Damping Characteristics ◽  
Mr Fluids

DAMPING CHARACTERISTICS OF MR FLUIDS IN LOW MAGNETIC FIELDS

2001 ◽  
Vol 15 (06n07) ◽  
pp. 829-836 ◽  
Author(s):  
HIDEYA NISHIYAMA ◽  
TADAMASA OYAMA ◽  
TOYOHISA FUJITA
Keyword(s):  
Magnetic Fields ◽  
Flat Plate ◽  
Phase Difference ◽  
Magnetic Fluid ◽  
Cluster Formation ◽  
Cluster Structure ◽  
Viscous Drag ◽  
Damping Characteristics ◽  
Mr Fluids ◽  
Viscous Drag Force

The cluster structure is visualized and the physical properties of new two types of nano MR fluids are measured in the applied magnetic fields. Correlating to these measurements, the damping characteristics of an oscillating flat plate immersed in two types of nano MR fluids such as damping amplitude, phase difference, viscous damping coefficient and viscous drag force acted on a flat plate are experimentally clarified, comparing with those of commercial magnetic fluid from the fluiddynamic points of view. It is shown that the resonance of damping amplitude and phase difference are very sensitive to the applied magnetic field, and further the damping effect of MR fluid is about ten times stronger than that of the commercial magnetic fluid even in low magnetic fields of 50–100 Gauss due to the robust cluster formation.

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.

1. What is geophysics?

2018 ◽  
pp. 1-5
Author(s):  
William Lowrie
Keyword(s):  
Magnetic Fields ◽  
Physical Properties ◽  
Complex Behaviour ◽  
Tectonic Plates ◽  
Natural Processes ◽  
Research Fields ◽  
The Earth ◽  
Deep Interior ◽  
Wide Range ◽  
Geophysical Investigations

Geophysics is a field of earth sciences that uses the methods of physics to investigate the complex physical properties of the Earth and the natural processes that have determined and continue to govern its evolution. ‘What is geophysics?’ explains how geophysical investigations cover a wide range of research fields—including planetary gravitational and magnetic fields and seismology—extending from surface changes that can be observed from Earth-orbiting satellites to complex behaviour in the Earth’s deep interior. The timescale of processes occurring in the Earth also has a very broad range, from earthquakes lasting a few seconds to the motions of tectonic plates that take place over tens of millions of years.

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.

INFLUENCE OF PARTICLE SHAPE ON THE PROPERTIES OF MAGNETORHEOLOGICAL FLUIDS

2007 ◽  
Vol 21 (28n29) ◽  
pp. 5018-5025 ◽  
Author(s):  
R. C. BELL ◽  
E. D. MILLER ◽  
J. O. KARLI ◽  
A. N. VAVRECK ◽  
D. T. ZIMMERMAN
Keyword(s):  
Magnetic Fields ◽  
Particle Shape ◽  
Silicone Oil ◽  
Pure Nickel ◽  
Spherical Particles ◽  
Volume Percent ◽  
Nickel Carbonyl ◽  
Rheological Measurements ◽  
Mr Fluids ◽  
Nickel Particles

We present studies of the rheological properties and dispersion stability of MR fluids as a function of particle shape by comparing fluids made with uniform nickel spheres to those employing nickel microwires suspended in silicone oil. The wires were fabricated using template-based electrodeposition having diameters in the range 300 ± 30 nm and lengths in the range of 5 – 25 μm . The properties of these wires were compared to commercial nickel carbonyl spheres (1–10 μm dia.). Qualitatively, the off-state (field off) viscosity of fluids containing only wires was found to be substantially greater than those fluids that contain only spherical particles. Rheological measurements of the on-state viscosities were conducted using a custom rheometer equipped with an electromagnet capable of magnetic fields up to 0.6 T. Placed in this field, we observed yield stresses of 1.88 ± 0.23 and 1.86 ± 0.26 kPa for 7.6 volume percent of pure nickel spheres and microwires, respectively. The fluids containing spherical nickel particles tended to settle rather quickly (< 20 minutes), while those containing only wires remained suspended even after several months.

PHYSICAL MODELING OF DAMPING CHARACTERISTICS OF MR FLUIDS

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2704-2710
Author(s):  
JEROME SARRAZIN ◽  
JEROME CLARACQ ◽  
JEAN-PIERRE MONTFORT
Keyword(s):  
Experimental Data ◽  
Physical Modeling ◽  
Magnetic Force ◽  
Viscoelastic Behavior ◽  
Complex Shear Modulus ◽  
Mechanical Spectroscopy ◽  
Viscous Forces ◽  
Damping Characteristics ◽  
Mr Fluids ◽  
Complex Shear

The behavior of MR fluids involved in industrial devices is often modeled by analogical models which do no link the parameters with the physical properties of the fluid. From the equations of fluid mechanics, we give a physical meaning to parameters such as friction, elastic and mass coefficients used in the mentioned models. The predictions are checked with experimental data which mimic the behavior of devices such as antiseismic systems. The viscoelastic behavior of MR fluids is characterized by mechanical spectroscopy. The complex shear modulus G *(ω) contains all the information about the restoring and viscous forces. For example, the relation between elastic modulus, yield stress and magnetic force is discussed in terms of strain amplitude.

Sign in / Sign up

Export Citation Format

Share Document