Enhanced magnetorheological effect and sedimentation stability of bimodal magnetorheological fluids doped with iron nanoparticles

2020 ◽  
pp. 1045389X2092483 ◽  
Author(s):  
Wanning Zhu ◽  
Xufeng Dong ◽  
Hao Huang ◽  
Min Qi
Keyword(s):  
Magnetic Field ◽  
Rheological Properties ◽  
Carbonyl Iron ◽  
Iron Nanoparticles ◽  
Arc Discharge ◽  
Magnetorheological Fluids ◽  
Mechanism Study ◽  
Adsorbed State ◽  
Sedimentation Stability ◽  
Magnetorheological Effect

The improvement of properties of magnetorheological fluids and mechanism study has long been a classic area within the field of magnetorheological materials. This article was undertaken to dope the iron nanoparticles synthesized by direct current electric arc discharge with the traditional carbonyl iron powders to prepare bimodal magnetorheological fluids with different doping ratios. Their rheological properties and sedimentation stability were evaluated to explore the influence rules and mechanisms. The results indicate that the effect of the addition of iron nanoparticles on rheological properties under magnetic field is a combination of two opposing factors such as the strengthening of the structure and the weakening of magnetization. The sedimentation stability of the bimodal magnetorheological fluids improved significantly with the increase in the proportion of iron nanoparticles, which is attributed to the help of both free state and adsorbed state iron nanoparticles in magnetorheological fluids. Furthermore, within a specific magnetic field strength range, the bimodal magnetorheological fluids with a small proportion of iron nanoparticles can achieve an improvement in both rheological property and sedimentation stability compared with carbonyl iron particles–based magnetorheological fluids.

Visualizing Rheological Mechanism of Magnetorheological Fluids

2021 ◽  
Author(s):  
Yurui Shen ◽  
Dezheng Hua ◽  
Xinhua Liu ◽  
Weihua Li ◽  
Grzegorz Krolczyk ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Rheological Properties ◽  
Magnetic Dipole ◽  
Laser Scanning ◽  
Magnetic Particles ◽  
Three Dimensional ◽  
Confocal Laser Scanning Microscope ◽  
Magnetorheological Fluids ◽  
Confocal Laser ◽  
Observation Method

Abstract In order to study the rheological properties of aqueous magnetorheological fluids (MRFs) from microscopic point of view, an experimental observation method based on the fluorescence confocal laser scanning microscope is proposed to clearly produce the chain shape of the magnetic particles. Firstly, the mathematical model of the magnetic particles is established in a magnetic field using the magnetic dipole theory, and the MRFs with different fraction volumes and different magnetic fields are investigated. Furthermore, an aqueous MRFs experiment is prepared, in which the magnetic particles are combined with Alexa 488 fluorescent probe. On this basis, an observation method is innovatively developed using two-dimensional (2D) and three-dimensional (3D) image analysis by the fluorescence confocal microscope. The rheological mechanism of the aqueous MRFs is investigated using four different types of MRFs in an external magnetic field. The analysis results demonstrate that the simulation and experimental rheological properties of the MRFs are consistent with the magnetic dipole theory. Moreover, the proposed method is able to real-time observe the rheological process of the MRFs with a very high resolution, which ensures the correctness of the analysis results of the rheological mechanism.

Magnetorheological properties and polishing characteristics of silica-coated carbonyl iron magnetorheological fluid

2017 ◽  
Vol 29 (1) ◽  
pp. 137-146 ◽  
Author(s):  
Kwang Pyo Hong ◽  
Ki Hyeok Song ◽  
Myeong Woo Cho ◽  
Seung Hyuk Kwon ◽  
Hyoung Jin Choi
Keyword(s):  
Magnetic Field ◽  
Surface Roughness ◽  
Field Intensity ◽  
Carbonyl Iron ◽  
Material Removal ◽  
Magnetic Field Intensity ◽  
Magnetorheological Fluid ◽  
Wheel Speed ◽  
Magnetorheological Fluids ◽  
Experimental Conditions

While magnetorheological fluids can be used for ultra-precise polishing, for example, of advanced optical components, oxidation of metallic particles in water-based magnetorheological fluids causes irregular polishing behavior. In this study, carbonyl iron microspheres were initially coated with silica to prevent oxidation and were used to polish BK7 glass. In addition, their rheological and sedimentation characterizations were investigated. Material removal and surface roughness were analyzed to investigate the surface quality and optimal experimental conditions of polishing wheel speed and magnetic field intensity. The maximum material removal was 0.95 µm at 95.52 kA/m magnetic field intensity and 1854 mm/s wheel speed. A very fine surface roughness of 0.87 nm was achieved using the silica-coated magnetorheological fluid at 47.76 kA/m magnetic field intensity and 1854 mm/s wheel speed.

ANALYSIS OF THE POTENTIAL USAGE OF SELECTED MAGNETIC FLUIDS IN THRUST SLIDE BEARINGS

Tribologia ◽  
2016 ◽  
Vol 269 (5) ◽  
pp. 41-49 ◽  
Author(s):  
Wojciech HORAK ◽  
Józef SALWIŃSKI ◽  
Marcin SZCZĘCH
Keyword(s):  
Magnetic Field ◽  
Rheological Properties ◽  
Mechanical Energy ◽  
Magnetic Fluids ◽  
Magnetorheological Fluids ◽  
Machine Design ◽  
Rheological Characteristics ◽  
New Horizons ◽  
Controlled Systems ◽  
Ferromagnetic Fluids

Magnetic fluids are substances whose rheological properties can be actively influenced by treatment with a magnetic field. Two main types of magnetic fluids can be distinguished: ferromagnetic fluids, and magnetorheological fluids. Ferrofluids are mostly used in sealing engineering, whereas magnetorheological fluids are usually applied in controlled systems for the dissipation of mechanical energy, like brakes and dampers. The ability to control the rheological properties of magnetic fluids opens new horizons for development in machine design, among others in the areas of bearing engineering. The paper presents a comparative analysis of the rheological characteristics of selected magnetic fluids with a focus on the possible areas of the application of these substances in bearing engineering.

MAGNETORHEOLOGICAL FLUIDS AND THEIR PROPERTIES

2005 ◽  
Vol 19 (01n03) ◽  
pp. 593-596 ◽  
Author(s):  
J. M. HE ◽  
J. HUANG
Keyword(s):  
Magnetic Field ◽  
Yield Strength ◽  
Rheological Properties ◽  
Yield Stress ◽  
Applied Magnetic Field ◽  
Magnetorheological Fluids ◽  
Mr Fluid ◽  
Variable Yield ◽  
Mr Fluids

Magnetorheological (MR) fluids are materials that respond to an applied magnetic field with a change in their rheological properties. Upon application of a magnetic field, MR fluids have a variable yield strength. Altering the strength of the applied magnetic field will control the yield stress of these fluids. In this paper, the method for measuring the yield stress of MR fluids is proposed. The curves between the yield stress of the MR fluid and the applied magnetic field are obtained from the experiment. The result indicates that with the increase of the applied magnetic field the yield stress of the MR fluids goes up rapidly.

An Investigation of the Behaviour of Magnetorheological Fluids in the Rotary Shock-Absorber

2012 ◽  
Vol 628 ◽  
pp. 512-517 ◽  
Author(s):  
Sławomir Kciuk ◽  
Monika Kciuk ◽  
Roman Turczyn ◽  
Paweł Martynowicz
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Structure Formation ◽  
Internal Structure ◽  
Carbonyl Iron ◽  
Shock Absorber ◽  
Experimental Studies ◽  
Magnetorheological Fluids ◽  
Control Current

The main aim of the article was to present the investigation results of created megnetorheological fluids using carbonyl iron (CI) particles and analyse their behaviour in terms of the internal structure formation by a control of external magnetic field. Results of the experimental studies of a prototype magnetorheological rotary shock-absorber at various magnitudes of control current was presented in this paper.

Microstructure evolution based particle chain model for shear yield stress of magnetorheological fluids

2020 ◽  
Vol 32 (1) ◽  
pp. 49-64
Author(s):  
Yongbo Peng ◽  
Pei Pei
Keyword(s):  
Magnetic Field ◽  
Rheological Properties ◽  
Microstructure Evolution ◽  
Volume Fraction ◽  
Magnetorheological Fluids ◽  
Model Verification ◽  
Structure Evolution ◽  
Chain Model ◽  
Shear Model ◽  
Proposed Model

To predict the shear stress of magnetorheological fluids (MRFs) under magnetic field and shear flows, a meso-microscale shear model is proposed based on the entire course of particle aggregates and chains. For this purpose, a systematic study on the microstructure evolution and rheological properties of MRFs is conducted by using molecular dynamics simulations. An efficient chain identification technique is introduced to count the number of particle chains within the suspension system. From the perspective of particle-level simulations, the microstructured behavior of MRFs involving particle aggregation and internal structure evolution of magnetorheological suspensions are addressed. Shear properties of MRFs derived by the proposed model are studied, and model verification by comparison with previous experimental data and predictions of the existing structural viscosity model is included as well. It is revealed that the proposed meso-microscale shear model exhibits satisfactory accuracy and efficiency for describing the rheological properties of MRFs. Besides, the critical factors linked with rheological properties of MRFs such as magnetic field strength, particle volume fraction and shear rate, are analyzed, further demonstrating the applicability of the proposed model in design and optimization of MRFs.

An experimental study on the effects of temperature and magnetic field strength on the magnetorheological fluid stability and MR effect

Soft Matter ◽  
2015 ◽  
Vol 11 (22) ◽  
pp. 4453-4460 ◽  
Author(s):  
Yahya Rabbani ◽  
Mahshid Ashtiani ◽  
Seyed Hassan Hashemabadi
Keyword(s):  
Magnetic Field ◽  
Experimental Study ◽  
Field Strength ◽  
Rheological Properties ◽  
Carbonyl Iron ◽  
Silicone Oil ◽  
Magnetorheological Fluid ◽  
Effects Of Temperature ◽  
The Stability ◽  
Mr Effect

In this study, the stability and rheological properties of a suspension of carbonyl iron microparticles (CIMs) in silicone oil were investigated within a temperature range of 10 to 85 °C.

Temperature Behavior of Magnetorheological Fluids

2005 ◽  
Vol 15 (2) ◽  
pp. 116-121 ◽  
Author(s):  
F. Zschunke ◽  
R. Rivas ◽  
P.O. Brunn
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Fluid Flows ◽  
Magnetorheological Fluids ◽  
Fluid Viscosity ◽  
Damping Force ◽  
Friction Dampers ◽  
Fluid Behavior ◽  
Magnetorheological Effect ◽  
The Magnetic Field

AbstractMagnetorheological fluids (MRFs) show a high but reversible rise of the viscosity upon application of an external magnetic field. This effect can be utilized in controllable friction dampers where the MR fluid flows through a gap with a adjustable magnetic field. The change in the magnitude of the magnetic field leads to a change of the viscosity of the fluid which in turn effects the pressure drop in the system. So the damping force can be controlled by the magnitude of the external magnetic field. This energy dissipation leads to a rise of the damper temperature. For designing those dampers it is vital to know the influence of the geometry, which influences the magnetic field strength, as well as the flow properties and the temperature dependence of the magnetorheological effect. An approach to the solution of this problem is shown by using an Arrhenius relationship, where the fluid viscosity is a function of the shear rate, the magnetic field and the temperature. The aim of the here presented research is to show how the fluid behavior can be simply modeled for use in CFD codes to design dampers or other applications.

Synthesis and characterization of novel flake-shaped carbonyl iron and water-based magnetorheological fluids using laponite and oleic acid with enhanced sedimentation stability

2021 ◽  
pp. 1045389X2098700
Author(s):  
Chandra Shekhar Maurya ◽  
Chiranjit Sarkar
Keyword(s):  
Magnetic Field ◽  
Oleic Acid ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Carbonyl Iron ◽  
Vibration Isolation ◽  
Zero Field ◽  
Sedimentation Stability ◽  
Mr Fluids ◽  
Water Based

In this study, micron-sized flake shaped carbonyl iron (CI) water-based MR fluids were prepared with adding laponite and oleic acid as an additive and surfactant, respectively. The MR suspensions are comprised of the fixed CI particles and water weight %, while weight % of laponite and oleic acid changes from 1 to 3 wt% and 0.5 to 1.5 wt%, respectively. The remarkable enhancement in magnetorheological properties was obtained with improved sedimentation stability for CI/water MR suspensions with the addition of laponite and oleic acid. It was found that at the lowest magnetic field strength, the higher laponite concentration is effective, while at the highest magnetic field strength, the smaller concentration was effective. It was because of the combined effect of the field-induced CI chains and the laponite clay gel network. Its storage moduli showed a stable plateau area for whole angular frequencies, suggesting distinguished solid-like behavior of the MR fluid. Finally, a novel correlation was obtained between the initial settling rate of the CI particles and magnetorheological behavior of CI/laponite/OA MR suspensions with 1 wt% laponite and 0.5 wt% oleic acid, which has less zero-field, high on-state shear stress with enhanced sedimentation stability. The prepared MR fluids are a reliable industrial application vibration-isolation, clutch, and brake.

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