Preparation of magnetorheological fluid

1. 21
Available online at: www.isssonline.in/journal/03paper10.pdf. Paper submitted on April 03, 2014; Accepted on May 04, 2014.
INSTITUTE OF SMART STRUCTURES AND SYSTEMS (ISSS)
J. ISSS Vol. 3 No. 2, pp. 23-26, Sept. 2014.
JOURNAL OF ISSS
REGULAR PAPER
Preparation of a Silicon
oil based Magneto
Rheological Fluid and an
Experimental Study of its
Rheological Properties
using a Plate and Cone
Type Rheometer
Shreedhar Kolekar1
, Rajashekar V. Kurahatti2
,
Prashanth P.K1
, Vikram Kamble1
, Nitin Reddy1
Mechanical Engineering Department,
St. Joseph Engineering College, Mangalore - 575028.
2
Mechanical Engineering Department Basaveshwar
Engineering College, Bagalkot - 587102
Corresponding Author: shreedharkolekar@yahoo.co.in
Abstract
Magnetorheological (MR) fluids are suspensions of micron-sized
magnetisable particles disperse in a nonmagnetic carrier fluid. The
essential characteristic of these materials is that they can be rapidly
and reversibly varied from the state of a Newtonian-like fluid to
that of a stiff semisolid with the application of a moderate magnetic
field. In this research work a silicon based magnetorheological fluid
is prepared in the laboratory and tested using a cone and plate type
rheometer for finding its characteristics of a MR fluid by measuring
different rheological properties such as viscosity, shear stress, yield
stress etc for different samples in detail. The properties of MR Fluids
in terms of storage modulus (G'), loss modulus (G'') and loss factor
(G''/G') are also presented.
1. Introduction
Magnetorheological (MR) materials consist of micron
size (typically 3 to 5 microns) particles which are
magnetically permeable and suspended in a non-
magnetic medium. When a magnetic field is applied,
the rheological properties of these materials are rapidly
and reversibly altered. The mechanism responsible for
this bulk effect is the induced magnetic interaction of
the particles within the matrix. In MR fluids, the mutual
interaction amongst the particles causes the formation
of chain-like structures aligned roughly parallel to the
applied magnetic field as shown in fig 1(A,B). It was first
introduced by Jacob Rabinow at the National Bureau
of Standards, now the National Institute for Science
and Technology, in the United States in the 1940s and
early 1950s . The configuration and rigidity of this
structure depends upon several factors including the
strength and distribution of the applied magnetic field.
MR fluids are often modeled as Bingham plastics with
a field dependent yield stress [Spasojevic et al. 1974].
MR solids have also been developed by incorporating
magnetically permeable particles into an elastomer
medium [Rigbi et al 1994]. Yield stresses of nearly 100
kPa have been reported in commercially available fluids
by Lord Corporation 1994. A finite stress is developed
to yield these chain structures [Jolly et al. 1996].
Hence, The tunability of the Rheological properties
Keywords:
Magnetorheological fluid, Shear
stress, Shear rate, Shear viscosity,
Phase angle.

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Please provide the correct text:
with the applied magnetic field provides the basis
for a wide variety of commercial applications of MR
Fluids including automobile clutches (Rabinow 1948),
seismic vibration control (Dyke et al. 1996),active
dampers (Spencer et al.1997), precision polishing
(Kordonski and Golini 1999) prosthetics (Carlson
et al. 2001), and drilling fluids (Zitha 2004). models
and mechanisms of chain formation(Parthasarathy
and Klingenberg 1996; Goncalves et al.2006) MR
Fluid formulation (Park et al.2010), MR fluids
research and technology has been reviewed numerous
times, with articles focusing on Rheology and flow
properties (de Vicente et al. 2011a), and applications
(Klingenberg 2001; Olabi and Grunwald 2007).
2 Composition and Properties of MR Fluid
2.1 Chemical Composition
A typical MR Fluid consists of 20-40 % by volume of
relatively pure soft iron particles,soft iron particles
size of 3-5 microns suspended in a carrier liquid such
as mineral oil, synthetic oil, water or glycol. A variety
of proprietary additives similar to those found in
commercial lubricants are commonly added to discourage
gravitational settling and promote particle suspension,
enhance lubricity, modify viscosity, and inhibit wear.
2.2 Physical properties of MR fluids
MR fluids exhibit dynamic yield strength values
in excess of 50 KPa for applied magnetic field
strength values of 150-250 kAm-1 and values over
100 KPa at saturation. An operational temperature
for MR fluids ranges from -40°C to +150°C.
Most of the researchers used carbonyl iron as particles
to scatter in an oil medium, for instance silicone oil W H
Li et al (1999) Muhammad Aslam et al (2006), Mark R.
Jolly et al (1998), S. Genc et al (2002), hydrocarbon oil
J Wang et al 2005, mineral oil J. H. Park et al (2001) J.
Claracq et al 2004 and hydraulic oil.
3 Experimental systems:
3.1 Preparation of Magneto rheological fluid samples
Preparation of MRFluid in the laboratory by using silicon
oil is explained in the paper by S Elizabeth Premalatha et
al (2012) Shreedhar Kolekar (2014) in detail.
Here in this research work MR Fluid is prepared by using
a low viscosity oil such as Silicon oil with iron powder
in different concentrations and white lithium grease as
an additive.
3.2 Composition of MR Fluid
Silicon oil (viscosity 0.340 Pas) Density=0.9659gm/
cm-3, Iron particles-4.7µm (BASF 2006) White lithium
grease as an additive.
Table (1) Composition of constituents used and their
weight percentage.
3.3 Preparation of MR Fluid
(1) The silicon oil is first mixed with grease in very small
concentrations using a mechanical stirrer. This mixing
process is done for 1 hour continuously till it is seen that
the grease particles are dissolved and suspended in the
silicon oil. The figure below shows how the grease mixed
with silicon oil looks like on the completion of mixing.
Figure 1: Magnetorheological material A- before, B – and after the
application of an external magnetic field.
Figure 2: Silicon mixed with grease.
Samples wt. % of materials for the
preparation of MR Fluid
Fe Particle Silicone oil Grease
A 22% 78% 12%
B 40% 60% 12%
C 30% 70% 12%
Silicon Oil Based Magneto Rheological Fluid and an Experimental Study of its Rheological Properties

3. 23
Journal of ISSS
Kolekar et al.
(2) After the solution is prepared as seen above, the
required weighed iron powder is then poured into it, in
parts while the stirring is carried out. As the iron powder
mix into the container, it gets mixed along with the
solution and becomes highly viscous and appears black
in color. This stirring is carried out for about an hour and
the end result obtained is MR Fluid.
In the graph above the MR Fluid exhibits the linear
viscosity relationship for the sample A&C decrease
along with increase in shear rate, but sample B shows a
high non linearity in terms of viscosity by an increase in
the shear rate.
4.1 Frequency sweep (sample A):
In this part, the applied strain amplitude for all three
MR samples was varied from 0.01 – 10%. And it can
be seen that G', G'' and G''/G' are all very sensitive to
the applied strain. The higher the strain, the higher the
storage (elastic) modulus G' and loss (viscous) modulus
G''. This may be attributed to the internal structures of
the iron particles. Moreover, the storage modulus (G') of
the MR Fluid was enhanced on increasing the applied
magnetic field.
In this way we prepared MR Fluid and it is almost 92%
accurate in its rheological properties as compared to the
commercially available fluid like Lord Corporation.
3.4 Characterization: The tests were carried out using
a Kinexus (Plate and cone type) rheometer for finding
its rheological properties such as viscosity, shear stress,
yield stress etc for different samples.
Specification of apparatus:
Plate and cone diameter of 20mm through 60mm was used
as the standard size range. Its ability to configure three
critical rheometer functions independently, Rotational
(shear) control - torque, speed and position, Vertical
(axial) control – gap and normal Force ,temperature
control, all rotational shear-based testing, advanced
vertical (axial) testing including squeeze flow and track
testing was measured.
4 Rheology test results:
Figure 3: Prepared MR Fluid.
Figure 5: (a) Storage and Loss modulus V/s Frequency
(b) Phase angle V/s Frequency of sample A
Figure 4: Viscosity v/s shear rate (flow curve) all samples.
(a)
(b)
4.2 Frequency sweep (sample B):
In the graph above the MR Fluid exhibits the linear
viscosity relationship for the sample A&C decrease
along with increase in shear rate, but sample B shows a
high non linearity in terms of viscosity by an increase in
the shear rate.

4. 24
INSTITUTE OF SMART STRUCTURES AND SYSTEMS (ISSS)
The storage modulus G', loss modulus G'' and loss factor
G''/G' were measured using the amplitude sweep method.
GI and GII increase with a decrease in strain amplitude,
as the frequency increases. However, the loss factor
increases with increasing strain amplitude. The storage
modulus does not rely on frequency.
5. Conclusions
From the results above, it is clear that as the concentration
of iron particles varies, the rheological properties also
vary. The higher the weight fraction of iron particles,
the higher the storage modulus and loss factor. The
rheological property does not rely much on frequency.
Acknowledgements
Our sincere appreciation to Malvern Aimil Instruments,
New Delhi for their kind support in this research work.
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Figure 6: (a) Storage and Loss modulus V/s Frequency
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Shreedhar Kolekar did his M.Tech(Machine Design)
from Visvesvaraya Technological University Belgaum,
currently he is Assistant Professor in Mechanical
Engineering Department,St Joseph Engineering
college Mangalore. His research interests includes smart
materials, Vibration analysis,Semiactive suspension control,
fatigue of composites.
Dr. Rajashekar V. Kurahatti obtained his PhD from
Metallurgical and Materials Engineering department
of National Institute of Technology Karnataka in 2012.
He has teaching experience of 17 years. Presently he
is working as Associate Professor in Basaveshwar Engineering
College, Bagalkot. He has published 6 papers in international
journals and presented 12 papers in international conferences.
His research areas are heat treatment, composites and
nanotechnology.
Prashanth.P.K pursuing M.Tech in Computational
Analysis in Mechanical sciences from St.Joseph
Engineering college Mangalore.
Vikram Kamble Pursuing B.E(Mechanical
Engineering) from St Joseph Engineering College
Mangalore.His research interests in smart materials
like magnetorheological fluid, materials engineering.
Nitin Reddy Pursuing B.E(Mechanical Engineering)
fromStJosephEngineeringCollegeMangaloreresearch
interests in smart materials like magnetorheological
fluid, materials engineering.