Synthesis and field dependent shear stress evaluation of stable MR fluid for brake application

2017 ◽  
Vol 69 (5) ◽  
pp. 655-665 ◽  
Author(s):  
Lijesh K.P. ◽  
Deepak Kumar ◽  
Harish Hirani
Keyword(s):  
Shear Stress ◽  
Oleic Acid ◽  
Silicone Oil ◽  
Ammonium Hydroxide ◽  
Iron Particles ◽  
Mr Fluid ◽  
Content Type ◽  
Weight Percentage ◽  
Mr Fluids ◽  
Brake Application

Purpose The purpose of this paper is to report on the development of magnetorheological (MR) fluids, having high on-state shear stress/viscosity, low off-state shear stress/viscosity, good redispersibility and stable suspension of carbonyl iron particles, using tetramethyl ammonium hydroxide (TAH) and oleic acid. Design/methodology/approach MR fluids for use in brakes are synthesized using different weight percentages of silicone oil, TAH, oleic acid and iron particles. The effects of TAH and oleic acid are studied. Shear stress is measured as a function of magnetic field on a magneto-rheometer. The images of MR particles settling with time are presented. The test set-up used to evaluate the performance of the MR fluids synthesized for brake application is detailed. Finally, a significant improvement in the MR performance of brakes is reported. Findings The MR fluid having 0.25 Wt.% oleic acid showed low off-state viscosity/shear stress and high on-state viscosity/shear stress. A higher weight percentage of TAH in the MR fluid further reduced the low off-shear stress and increased the high on-state shear stress with better stability. Originality/value Improvement of MR brake performance by adding surfactants like TAH and oleic acid has been the subject matter of several studies in the past, but these studies used a fixed percentage of surfactants in MR fluids. In the present work, the optimum percentage of TAH and oleic acid for an improved braking performance is determined by varying their content in the MR fluid, which has not been reported in any other work thus far.

Experimental studies on magnetorheological brake containing plane, holed and slotted discs

2017 ◽  
Vol 69 (2) ◽  
pp. 116-122 ◽  
Author(s):  
Chiranjit Sarkar ◽  
Harish Hirani
Keyword(s):  
Experimental Studies ◽  
State Condition ◽  
Frictional Torque ◽  
Iron Particles ◽  
Low Friction ◽  
Mr Fluid ◽  
Content Type ◽  
Shear Rates ◽  
Mr Fluids ◽  
Braking Torque

Purpose This study aims to design an ideal magnetorheological (MR) brake that exerts negligible frictional torque in the off-state condition and controllable frictional torque in the on-state condition. Design/methodology/approach Silicone-based MR fluid, containing 9 per cent volume carbonyl iron particles, has been synthesized and used. The synthesized MR fluid is advantageous in maintaining low friction losses in off-state conditions. A magneto-rheometer has been utilized to characterize the off-state viscosity of the MR fluid at variable shear rates and shear stress of MR fluids at various magnetic fields. A mechanism to enhance the braking torque in the on-state condition has been designed and developed. An experimental test rig has been developed to capture the torque characteristics of the developed MR brakes. Three different designs of MR discs have been experimented under a magnetic field varying from 0 to 375 kA/m. Experimental results of braking torque under shear and compression modes have been presented. Findings Slotted disc MR brake gives much better torque performance. Originality/value The braking torque results motivate to use the slotted disc MR brake for high torque application.

RELATIONSHIP BETWEEN CHAIN STRUCTURES AND VISCOSITY IN THE MAGNETO-RHEOLOGICAL SUSPENSIONS STABLE DISPERSING DIFFERENT CONCENTRATION OF IRON PARTICLES WITH SMECTITE

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2364-2370 ◽  
Author(s):  
A. SHIBAYAMA ◽  
T. MIYAZAKI ◽  
T. OTOMO ◽  
T. FUJITA ◽  
K. SHIMADA
Keyword(s):  
Magnetic Field ◽  
Shear Stress ◽  
Silicone Oil ◽  
Shear Stresses ◽  
Hall Probe ◽  
Magnetic Field Direction ◽  
Iron Particles ◽  
Mr Fluid ◽  
Volume Percentage ◽  
The Magnetic Field

Different concentration of spherical iron particles (7 to 8 μm) are dispersed in silicone oil to increase the stability with smectite. The concentration of iron particles is maintained between 2 and 40 volume %. The solenoid coil surrounding the cylinders applies the magnetic field in the longitudinal direction of cylinder, when the cylindrical viscometer is employed. As the magnetic field increases, the diameter of chain structure also increases. The shear stress versus shear rate is proportional relation since the viscosity enlarges as the magnetic field increases at small concentration of iron in MR fluid. Additionally, the more increase of the magnetic field strength caused the decrease of the shear stresses at large concentration of iron in MR fluid, while the share rate is increased for the open system of the cylinders. It is assumed that wider clusters or wider chain structures are partly produced in the cylinder under the certain magnetic field. Therefore, the shear stress is not uniformly increased. On the other hand, when the cone and plate viscometer is used, the magnetic field direction is perpendicular to the flow direction. The shear stress versus share rate behaves like a Bingham fluid type under the effect of the magnetic field. As increasing the iron particles volume %, the chain structures cannot increase and make other ring type structures. When the magnetic field is measured by hall probe, the magnetic field decreased at some amount of volume percentage of iron suspension because of shield effect.

PREPARATION AND ABRASION PROPERTIES OF MAGNETO-RHEOLOGICAL FLUID OF DISPERSED SILICA-COATED IRON

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1121-1127 ◽  
Author(s):  
A. SHIBAYAMA ◽  
T. OTOMO ◽  
Y. AKAGAMI ◽  
K. SHIMADA ◽  
T. FUJITA
Keyword(s):  
Carbonyl Iron ◽  
Spherical Particles ◽  
Fluid Viscosity ◽  
Iron Particles ◽  
Mr Fluid ◽  
Abrasion Test ◽  
Silicon Oil ◽  
Mr Fluids ◽  
Transmission Oil ◽  
Magneto Rheological

In this study, a magneto-rheological fluid dispersed by silica-coated iron was developed and its properties such as fluid viscosity (shear stress or shear rate) and abrasion were investigated. The metallic iron coated by silica dispersed in magneto-rheological fluid was prepared by H 2 reducing of precipitated magnetite ( Fe 3 O 4). Then, the magneto-rheological fluid (MR fluid) for the seal was prepared with silica-coated iron or carbonyl iron (HQ type; diameter of 1.6-1.9 10-6m) and two solvent oils i.e. silicon oil (SH200cv, 10000cSt) and CVT oil (T-CVTF, automobile transmission oil). It was observed that the MR fluid viscosity of CVT oil with HQ particles is lower in every fluid condition. Furthermore, the surface roughness of polyvinyl plate after abrasion test for MR fluid with silica coated iron and CVT oil as solvent was higher compared to the other types of MR fluids. The results indicated that carbonyl iron (spherical particles) and silica-coated iron particles dispersed in silicon oil are feasible to be used where the low abrasion in mechanics is required.

Preparation of Magnetorheological Fluid and Study on Its Rheological Properties

2014 ◽  
Vol 13 (02) ◽  
pp. 1450009 ◽  
Author(s):  
Shreedhar Kolekar
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Rheological Properties ◽  
Magnetorheological Fluid ◽  
Magnetic Flux Density ◽  
Iron Loading ◽  
Iron Particles ◽  
Mr Fluid ◽  
Carrier Fluid ◽  
System Type

The present paper focuses on preparation and process of the magnetorheological (MR) fluid whose carrier fluid is silicone-based oil and its additive is the commercial grease with different concentration of iron particles. General properties of MR fluid are discussed and rheological properties like shear rate, shear stress, viscosity of MR fluid can be found by using cone-and-plate sensor system-type rheometer. The result shows that shear stress as a function of magnetic flux density and viscosity does not strictly scale with iron loading.

Study on Design Method of Magneto-Rheological Fluid Shock Absorber Employing Shear Rate Profiles and Experimental Tests

2011 ◽  
Vol 121-126 ◽  
pp. 1095-1099
Author(s):  
Chang Rong Liao ◽  
J.H. Hao ◽  
D.X. Zhao ◽  
K.L. Wang
Keyword(s):  
Differential Equation ◽  
Shear Stress ◽  
Analytical Study ◽  
Shock Absorber ◽  
Damping Force ◽  
Mr Fluid ◽  
Annular Channels ◽  
Mr Fluids ◽  
Stress Profiles ◽  
Magneto Rheological

The flow differential equation for Magneto-rheological (MR) fluids in annular channels of MR fluid shock absorber is set up and several rational simplifications are made. Analytical shear stress profiles of MR fluids through annular channels are obtained via solution of the flow differential equation. An analytical study on MR fluid shock absorber is present employing shear stress profiles. Both boundary conditions and compatible conditions are established. Both flow velocity profiles and total volumetric flow rate are developed by integration by parts and numerical integration. The prediction method for damping force of MR fluid shock absorber is developed via simultaneous equations. The analytical study on MR fluid shock absorber is validated by means of reformative Herschel–Bulkley constitutive model, in which flow velocity profiles and flow regions boundary radii are drawed. A MR fluid shock absorber, which is designed and fabricated in Chongqing University, is tested by electro-hydraulic servo vibrator in National Center for Test and Supervision of Coach Quality. The experimental results reveal that the methodology is able to predict damping force of MR fluid shock absorber via shear rate profiles and experimental damping forces are in good agreement with analytical those.

Nanometer and Micron Sized Particles in a Bidisperse Magnetorheological Fluid

2003 ◽  
Author(s):  
N. M. Wereley ◽  
J. Trihan ◽  
S. Kotha ◽  
A. Suggs ◽  
R. Radhakrishnan ◽  
...  
Keyword(s):  
Yield Stress ◽  
Silicone Oil ◽  
Maximum Yield ◽  
Weight Percent ◽  
High Yield ◽  
Settling Rate ◽  
Mr Fluid ◽  
Carrier Fluid ◽  
Solids Loading ◽  
Mr Fluids

Conventional magnetorheological (MR) fluids are suspensions of micron sized particles in a hydraulic or silicone oil carrier fluid. Recently, research has been conducted into the advantages of using bidisperse MR fluids, which are mixtures of two different powder sizes in the MR suspension. The MR fluids investigated here use a mixture of conventional micron sized particles and nanometer sized particles. The settling rate of such bidisperse fluids using nanometer sized particles is reduced because thermal convection and Van der Waals forces experienced by the nanometer sized particles compete favorably with gravitational forces. This reduction in the settling rate comes at a cost of a reduction in the maximum yield stress that can be manifested by such an MR fluid at its saturation magnetization. There is a measurable and predictable variation in rheological properties as the weight percent of the nanometer sized particles is increased relative to the weight percent of micron size particles, while maintaining a constant solids loading in the MR fluid samples. All bidisperse fluids tested in this study have a solids loading of 60 weight% (wt%) of Fe particles. This study investigates the effect of increasing the weight percent of 30 nanometer (nominal) Fe particles relative to 30 micron (nominal) Fe particles on rheological characteristics such as yield stress and postyield viscosity. The goal of this study is to find an optimal composition of the bidisperse fluid that provides the best combination of high yield stress and low settling rate based on empirical measurements. The applicability of rheological models, such as the Bingham-plastic and the Hershel Buckley models, to the measured flow curves of these MR fluids is also presented.

Enhance the Yield Shear Stress of Magnetorheological Fluids

2001 ◽  
Vol 15 (06n07) ◽  
pp. 549-556 ◽  
Author(s):  
X. TANG ◽  
X. ZHANG ◽  
R. TAO
Keyword(s):  
Magnetic Field ◽  
Shear Stress ◽  
Yield Stress ◽  
Chain Structure ◽  
Single Chain ◽  
Compression Pressure ◽  
Sem Images ◽  
Mr Fluid ◽  
Mr Fluids ◽  
Yield Shear Stress

To enhance the yield shear stress of magnetorheological (MR) fluids is an important task. Since thick columns have a yield stress much higher than a single-chain structure, we enhance the yield stress of an MR fluids by changing the microstructure of MR fluids. Immediately after a magnetic field is applied, we compress the MR fluid along the field direction. SEM images show that the particle chains are pushed together to form thick columns. The shear force measured after the compression indicates that the yield stress can reach as high as 800 kPa under a moderate magnetic field, while the same MR fluid has a yield stress of 80 kPa without compression. This enhanced yield stress increases with the magnetic field and compression pressure and has an upper limit well above 800 kPa. The method is also applicable to electrorheological fluids.

SURFACE SHEAR STRESS ENHANCEMENT UNDER MR FLUID DEFORMATION

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2745-2750 ◽  
Author(s):  
S. GORODKIN ◽  
N. ZHURAVSKI ◽  
W. KORDONSKI
Keyword(s):  
Shear Stress ◽  
Surface Shear Stress ◽  
Iron Particles ◽  
Surface Shear ◽  
Mr Fluid ◽  
Particle Aggregates ◽  
Static Yield ◽  
Micro Topography ◽  
Static Yield Stress ◽  
Normal Magnetic Field

The effect of a regular surface micro topography on a magnitude of surface shear stress in a normal magnetic field under MR fluid deformation between two magnetic plates has been experimentally investigated. It was revealed that the static yield stress was increased by a factor of 2.8 for radially grooved plates as against smooth ones. The effect was most conspicuous at small iron particles volume fractions and strong magnetic fields. It is assumed that grooves create a magneto mechanical barrier that prevents the slip of particle aggregates against the wall.

scholarly journals A review on magnetically assisted abrasive finishing and their critical process parameters

2018 ◽  
Vol 5 ◽  
pp. 13 ◽  
Author(s):  
Chinu Kumari ◽  
Sanjay Kumar Chak
Keyword(s):  
Process Parameters ◽  
Silicone Oil ◽  
Mr Fluid ◽  
Carrier Medium ◽  
Mr Fluids ◽  
Abrasive Finishing ◽  
Critical Process Parameters ◽  
Removal Processes ◽  
Critical Process ◽  
Magnetically Assisted

Magnetically assisted abrasive finishing (MAAF) processes are the precision material removal processes that have been applied to a large variety of materials from brittle to ductile and from magnetic to non magnetic. The MAAF process relies on a unique “smart fluid”, known as Magnetorheological (MR) fluid. MR fluids are suspensions of micron sized magnetizable particles such as carbonyl iron, dispersed in a non-magnetic carrier medium like silicone oil, mineral oil or water. The MAAF processes overcome the limitation of abrasive flow machining by deterministically control the abrading forces by applying magnetic field around the workpiece. MAAF process is divided into two parts; one is magnetorheological finishing (MRF) and another is magnetorheological abrasive flow finishing (MRAFF). The MRAFF process gives better results as compared to results of MRF because it has additional reciprocating motion of MR fluid. In this article the attempt has been made to review various technical papers related to MRF and MRAFF. The experimental setups, process parameters, MR fluid, modeling & optimization and applications are discussed in this paper. This review article will be useful to academicians, researchers and practitioners as it comprises significant knowledge pertaining to MAAF.

Rheological behavior of lithium grease with CNTs/GNPs hybrid nanocomposite as an additive

2018 ◽  
Vol 70 (2) ◽  
pp. 331-338 ◽  
Author(s):  
Mohamed Ashour ◽  
Alaa Mohamed ◽  
Abou Bakr Elshalakany ◽  
Tarek Osman ◽  
Aly Khatab
Keyword(s):  
Shear Stress ◽  
Apparent Viscosity ◽  
Power Efficiency ◽  
Mechanical Equipment ◽  
Lithium Grease ◽  
Content Type ◽  
Weight Percentage ◽  
Mechanical Stirring ◽  
Cent Increase ◽  
Multi Walled Carbon Nanotubes

Purpose The purpose of this paper is to investigate the rheological characteristics of graphene nanoplatelets (GNPs) and hybridized nanocomposite consisting of multi-walled carbon nanotubes (MWCNTs) and GNPs as an additive on lithium-based grease. The experiments of nanogrease are examined in different values of shear stress, apparent viscosity, temperature and shear rate using Brookfield Programmable Rheometer DV-III ULTRA and characterized by high-resolution transmission electron microscope (HRTEM) and X-ray diffraction (XRD). Design/methodology/approach First, GNPs was mixed well with lithium grease using mechanical stirring at 3,500 rpm for 15 min at room temperature to form a homogenous composite at different concentrations (0.5, 1, 1.5, 2 and 2.5 Wt.%). Afterwards, MWCNTs and GNPs are mixed and dispersed well in the lithium grease using a sonication path for 30 min and mechanical stirring at 3,500 rpm for 15 min at 28°C to form a homogenous nanocomposite. Findings The results indicated that 1 Wt.% of GNPs is the optimum concentration. Subsequently, the weight percentage of additives varying between MWCNTs and GNPs are tested, and the result indicate that the grease containing GNPs had a 75 per cent increase in shear stress and 93.7 per cent increase in apparent viscosity over ordinary grease. Originality/value This work describes the inexpensive and simple fabrication of nanogrease for improving properties of lubricants, which improve power efficiency and extend lifetimes of mechanical equipment.

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