scholarly journals Research on a mechanical model of magnetorheological fluid different diameter particles

2021 ◽  
Vol 11 (1) ◽  
pp. 158-166
Author(s):  
Jun Qiu ◽  
Yiping Luo ◽  
Yuqing Li ◽  
Jiao Luo ◽  
Zhibin Su ◽  
...  
Keyword(s):  
Experimental Data ◽  
Shear Stress ◽  
Mechanical Model ◽  
Volume Fraction ◽  
Silicone Oil ◽  
Theoretical Data ◽  
Magnetorheological Fluid ◽  
Average Error ◽  
Shear Strain Rate ◽  
Particle Volume

Abstract In this paper, the chain structure of magnetorheological fluid (MRF) magnetic particles was studied and analyzed, the mechanical model of MRF with different diameter ferromagnetic particles was established, silicone oil-based MRF with different particle volume fractions was prepared, the shear properties of the MRF were tested, and the theoretical and experimental data were compared. The experimental results show that the shear stress is stable with the increase of shear strain rate under the action of the magnetic field, and it has a shear thinning effect. The shear stress increases linearly with the increase of particle volume fraction. The shear stress increases with the increase of magnetic induction intensity. After data analysis and in the case of control variables, the average error of improved theoretical data and experimental data is lower than that of previous theoretical data and experimental data, which verifies that the improved theory (mechanical model) has a certain accuracy.

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.

Radiative Transfer With Dependent Scattering by Particles: Part 2—Experimental Investigation

1986 ◽  
Vol 108 (3) ◽  
pp. 614-618 ◽  
Author(s):  
Y. Yamada ◽  
J. D. Cartigny ◽  
C. L. Tien
Keyword(s):  
Experimental Data ◽  
Experimental Investigation ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Small Particles ◽  
Particle Volume ◽  
Water Matrix ◽  
Test Cells ◽  
Radiative Scattering ◽  
Regime Map

Dependent radiative scattering by particles is experimentally investigated using plane-parallel cells containing latex spheres of 11, 2, and 0.08 μm diameter dispersed in an air or water matrix. The dependent scattering efficiencies and the bidirectional transmittance and reflectance were measured and compared with analytical results. The close-packed 2-μm spheres, which were expected to show dependent scattering from the previous criterion, gave results identical to independent scattering. Measured dependent scattering efficiencies of the small particles tested decrease with increasing particle volume fraction and were compared with those predicted by the theoretical investigation. The bidirectional transmittance and reflectance of dependent scattering were compared with those of independent scattering with the same number of spheres within the test cells. Several different patterns of dependent transmittance and reflectance appeared depending on the optical thickness. Finally, a newly proposed regime map bounding independent and dependent scattering is compared with the present and previous experimental data.

Analysis on the Distribution Law of WC Particles during Centrifugal Casting Process

2011 ◽  
Vol 117-119 ◽  
pp. 1610-1613
Author(s):  
Zhen Kai Zhao ◽  
Yan Pei Song ◽  
Zhi Ming Feng
Keyword(s):  
Volume Fraction ◽  
Centrifugal Casting ◽  
Particle Volume Fraction ◽  
Composite Layer ◽  
Theoretical Data ◽  
Casting Process ◽  
Mathematical Equation ◽  
Distribution Law ◽  
Particle Volume ◽  
Gradient Distribution

The mathematical physical model of the unmelted WC particle distribution in the centrifugal force field was established in cylindrical coordinate system using continuity theory and hydromechanics. According to the migration rule of WC particle in the Fe-C alloy melt under centrifugal field, the mathematical equation of particle volume fraction distribution including centrifugal casting parameters was formulated. The mathematical equations were calculated by solving the mathematical equation with numerical analysis, and also the distribution regularity of WC particle in composite layer under different temperature and different Centrifugal speed was achieved. The results show that the particle reinforced composite with a gradient distribution along thickness was prepared by centrifugal casting. The gradient distribution of the particle changes with pouring temperature and centrifugal speed. And the theoretical data accord with experiment data compared to the experimental measurement.

Pre-Yield Shearing Regimes of Magnetorheological Fluids

2012 ◽  
Author(s):  
Waad Nassar ◽  
Xavier Boutillon ◽  
José Lozada
Keyword(s):  
Magnetic Field ◽  
Shear Stress ◽  
Shear Strain ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Initial Response ◽  
Magnetic Pole ◽  
Particle Volume ◽  
Average Shear ◽  
The Magnetic Field

We analyzed experimentally the pre-yield regime of some MRFs. The hearing response is ruled by two successive regimes and limited by an interfacial phenomenon. The initial response is pseudo-elastic and independent from the magnetic field and of the particle volume fraction. The shear-stress limit of this regime is proportional to the square of the magnetic field and to the particle volume fraction. In the next regime, the shear strain is not uniform in the fluid. The increase in average shear stress varies linearly with the increase in average shear strain. The variation coefficient is proportional to the square of the magnetic field and decreases with the particle volume fraction. Finally, a loss of adhesion of the magnetic aggregates with the shearing plate or the magnetic pole occurs. The corresponding shear stress is proportional to the square of the magnetic field and to the particle volume fraction.

Modelling of a Magnetorheological Fluid Knee in a Prosthetic Leg

2016 ◽  
Author(s):  
The Nguyen ◽  
Saurabh Bapat ◽  
Xinli Wang
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Theoretical Model ◽  
Theoretical Data ◽  
Magnetorheological Fluid ◽  
Theoretical Modelling ◽  
Gap Size ◽  
Applied Current ◽  
Prosthetic Knee ◽  
Braking Torque

The purpose of the study is to theoretically model a prosthetic knee. A knee similar to magnetorheological fluid (MRF) brake is designed and the study focuses on modelling the MRF knee, predict the torque and compare it with the experimental data. The torque generated by the MRF knee is highly dependent on the gap size, angle, and the applied current. Here, the MRF knee features a non-circular rotor which results in a variable gap size for the MR fluid, between the stator and the rotor. Therefore, the gap size varies with the angle of the knee. When the current is applied and MR knee is subjected to a magnetic field, the yield stress produces the shear friction due to which the braking torque is generated. This derives the braking torque as a function of angle and applied current. A torque equation is derived from the theoretical data to yield the predicted results. In addition to the theoretical modelling and derived torque equations, the torque for the MRF fluid is also calculated experimentally. For the validation of the theoretical model and the derived torque equations, they were compared with the experimental results.

Dependence of Thermal Conductivity and Mechanical Rigidity of Particle-Laden Polymeric Thermal Interface Material on Particle Volume Fraction

2003 ◽  
Vol 125 (3) ◽  
pp. 386-391 ◽  
Author(s):  
Ravi S. Prasher ◽  
Paul Koning ◽  
James Shipley ◽  
Amit Devpura
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Mechanical Response ◽  
Volume Fraction ◽  
Effective Medium Theory ◽  
Particle Volume Fraction ◽  
Thermal Interface Material ◽  
Particle Volume ◽  
Thermal Interface ◽  
Medium Theory

This paper reports the measurement of the thermal conductivity of particle-laden polymeric thermal interface materials for three different particle volume fractions. The experimental data are further compared with the percolation model and effective medium theory. We then introduce a method of obtaining the contact resistance between the particles and the polymeric matrix by a combination of percolation modeling and experimental data. We also discuss the dependence of the mechanical response of these particle-laden polymers for different filler or particle loading. A novel mechanical length scale is defined to understand the mechanical response of these materials, and is correlated to the viscosity of these materials.

Development and Validation of Two-Way Fluid-Particle Coupling in Turbulent Flows for a CFD Code

2013 ◽  
Author(s):  
Jianjun Xiao ◽  
Anatoly Svishchev ◽  
Thomas Jordan
Keyword(s):  
Experimental Data ◽  
Turbulent Flows ◽  
Gas Flow ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Continuous Phase ◽  
Particle Dispersion ◽  
Solid Particles ◽  
Particle Volume ◽  
Discrete Phase

A Lagrangian approach was used in CFD code GASFLOW to describe particle dispersion in turbulent flows. One-way coupling between fluid and particle is often used due to its simplicity of implementation. However, in case of higher particle volume fraction or mass loading in the continuous phase, one-way coupling is not sufficient to simulate the interaction between fluid and particles. For instance, the liquid droplets released by a spray nozzle in the nuclear power plant will lead to a strong gas entrainment, and consequently impact the gas flow field. When the volume fraction of the discrete phase is not negligible compared to the continuous phase, the interaction between the continuous fluid and dispersed phase becomes significant. Two-way momentum coupling between fluid and solid particles was developed in CFD code GASFLOW. The dynamics of the discrete particles was solved by an implicit algorithm to ensure the numerical stability. The contribution of all particles to a fluid cell was treated as the source term to the continuous phase which was solved with Arbitrary-Lagrangian-Eulerian (ALE) methodology. In order to verify and validate the code, the calculation results were then compared to theoretical results, predictions of other CFD codes and experimental data. Predictions compared favorably with the experimental data. It indicates that the effect of two-way coupling is significant when the volume fraction of discrete phase is not negligible. Two-way coupling of mass, energy and turbulence will be implemented in the future development of the GASFLOW code.

scholarly journals Shear thinning in non-Brownian suspensions explained by variable friction between particles

2018 ◽  
Vol 860 ◽  
pp. 682-710 ◽  
Author(s):  
Laurent Lobry ◽  
Elisabeth Lemaire ◽  
Frédéric Blanc ◽  
Stany Gallier ◽  
François Peters
Keyword(s):  
Shear Stress ◽  
Friction Coefficient ◽  
Volume Fraction ◽  
Normal Load ◽  
Shear Thinning ◽  
Particle Volume ◽  
Normal Contact ◽  
Force Coupling ◽  
Applied Shear Stress ◽  
Variable Friction

We propose to explain shear-thinning behaviour observed in most concentrated non-Brownian suspensions by variable friction between particles. Considering the low magnitude of the forces experienced by the particles of suspensions under shear flow, it is first argued that rough particles come into solid contact through one or a few asperities. In such a few-asperity elastic–plastic contact, the friction coefficient is expected not to be constant but to decrease with increasing normal load. Simulations based on the force coupling method and including such a load-dependent friction coefficient are performed for various particle volume fractions. The results of the numerical simulations are compared to viscosity measurements carried out on suspensions of polystyrene particles ($40~\unicode[STIX]{x03BC}\text{m}$in diameter) dispersed in a Newtonian silicon oil. The agreement is shown to be satisfactory. Furthermore, the comparison between the simulations conducted either with a constant or a load-dependent friction coefficient provides a model for the shear-thinning viscosity. In this model the effective friction coefficient$\unicode[STIX]{x1D707}^{eff}$is specified by the effective normal contact force which is simply proportional to the bulk shear stress. As the shear stress increases,$\unicode[STIX]{x1D707}^{eff}$decreases and the jamming volume fraction increases, leading to the reduction of the viscosity. Finally, using this model, we show that it is possible to evaluate the microscopic friction coefficient for each applied shear stress from the rheometric measurements.

scholarly journals Eulerian-Eulerian Simulation of Particle-Liquid Slurry Flow in Horizontal Pipe

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Titus Ntow Ofei ◽  
Aidil Yunus Ismail
Keyword(s):  
Experimental Data ◽  
Particle Size ◽  
Radial Distribution ◽  
Pressure Loss ◽  
Particle Concentration ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Turbulence Models ◽  
Particle Volume ◽  
Horizontal Pipe

In this study, a computational fluid dynamics (CFD) simulation which adopts the inhomogeneous Eulerian-Eulerian two-fluid model in ANSYS CFX-15 was used to examine the influence of particle size (90 μm to 270 μm) and in situ particle volume fraction (10% to 40%) on the radial distribution of particle concentration and velocity and frictional pressure loss. The robustness of various turbulence models such as the k-epsilon (k-ε), k-omega (k-ω), SSG Reynolds stress, shear stress transport, and eddy viscosity transport was tested in predicting experimental data of particle concentration profiles. The k-epsilon model closely matched the experimental data better than the other turbulence models. Results showed a decrease in frictional pressure loss as particle size increased at constant particle volume fraction. Furthermore, for a constant particle volume fraction, the radial distribution of particle concentration increased with increasing particle size, where high concentration of particles occurred at the bottom of the pipe. Particles of size 90 μm were nearly buoyant especially for high particle volume fraction of 40%. The CFD study shows that knowledge of the variation of these parameters with pipe position is very crucial if the understanding of pipeline wear, particle attrition, or agglomeration is to be advanced.

THE RESPONSE TIME OF A ROTOR SYSTEM WITH A DISK-TYPE MAGNETORHEOLOGICAL FLUID DAMPER

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1506-1512 ◽  
Author(s):  
CHANGSHENG ZHU
Keyword(s):  
Response Time ◽  
Magnetic Particle ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Magnetorheological Fluid ◽  
Rotor System ◽  
Rapid Response ◽  
Particle Volume ◽  
Magnetorheological Fluid Damper ◽  
Fluid Damper

The response time of a rotor system supported upon a disk-type magnetorheological fluid damper operating on shear mode is measured experimentally. The effects of rotating speed, step current and magnetic particle volume fraction, on the response time are dealt with. It is shown that the dynamic response can be described by first 10% response time and rapid response time. Generally, the first 10% response time and the rapid response time are in order of less than 0.1 second and 0.1~0.4 second. The magnetic field strength, magnetic particle volume fraction and power supply have a great effect on the response time. The response time in dropping step current is several times longer than that in applying step current. There is a zero initial delay time at either applying or dropping the current, which is caused by the magnetizing or de-magnetizing process.

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