Transcript File - Vigyan Pariyojana

SEMINAR REPORT
ON
Magnetorheological Fluid
Guided by:Prof :- n.P.MUNGLE
Submitted by:Akshay Khatod .
Introduction
Controllable fluids are materials that respond to an
external excitation field.
When exposed to an electric or magnetic field, their
rheological behavior exhibits remarkable changes.
Theses martmaterials are commonly referred to as,
1. Magnetorheological (MR) fluids,
2. Electrorheological (ER) fluids,
3. Ferro (FR) fluids.
Introduction to MR Fluid
A magnetorheological fluid (MR fluid) is a type of smart
fluid in a carrier fluid, usually a type of oil. When subjected to
a magnetic field, the fluid greatly increases its apparent viscosity,
to the point of becoming a viscoelastic solid. Importantly, the
yield stress of the fluid when in its active ("on") state can be
controlled very accurately by varying the magnetic field
intensity.
History
William Kordonski was inventor of MR Fluid.
In 1974, William started work on
magnetorheological (MR) fluids, which are
suspensions of micron-size ferromagnetic
particles, such as iron, in fluids such as oil or
water.
William I. Kordonski,
Inventor of MR Fluid.
How it works
The magnetic particles, which are
typically micrometer or nanometer scale spheres or
ellipsoids, are suspended within the carrier oil are
distributed randomly and in suspension under normal
circumstances, as below.
When a magnetic field is applied, however, when
the fluid is contained between two poles , the
resulting chains of particles restrict the movement
of the fluid, perpendicular to the direction of flux,
effectively increasing its viscosity.
Modes of operations
An MR fluid is used in one of three
main modes of operation, these being
flow mode, shear mode and squeezeflow mode.
1. Flow mode
Flow mode, is one of the
operating modes in the MR
devices where the flow of the
MR fluid between motionless
plates or an orifice is created by
a pressure drop.
2. Shear mode
An MR fluid is situated between
two surfaces, whereby only one
surface slides or rotates in relation
to the other, with a magnetic field
applied perpendicularly to the
direction of motion of these shear
surfaces.
3. Squeeze-flow mode
Squeeze mode operates when a
force is applied to the plates in the
same direction of a magnetic field to
reduce or expand the distance
between the parallel plates causing
a squeeze flow.
Advantages
•Have higher magnitude of yield stress.
•Compared to ER fluids the simple construction of devices,
low power requirements for control, fast response.
• The squeeze mode of a MR damper has significant
advantages such as simple structure, clear effectiveness
and quick response.
•The fluids also have the advantages of using low voltage
power supplies in the range of 2 to 25 V, with current range
between 1 to 2 Amps and power ratings between 2-50
watts.
Disadvantages
•High density, due to presence of iron, makes them
heavy. However, operating volumes are small, so while
this is a problem, it is not insurmountable.
•High-quality fluids are expensive.
•Fluids are subject to thickening after prolonged use
and need replacing.
•Settling of Ferro-particles can be a problem for some
applications.
Application
1.Mechanical engineering
Magnetorheological
dampers these dampers are
mainly used in heavy industry
with applications such as heavy
motor damping, operator seat/cab
damping in construction vehicles,
and more.
2.Military and defense
The U.S. Army Research
Office is currently funding
research into using MR fluid
to enhance body armor.
3.Optics
Magnetorheological finishing a
magnetorheological fluid-based
optical polishing method, has
proven to be highly precise.
4.Automotive
The MR sponge clutch may be
used to provide launch control
of an automobile thereby
achieving smooth vehicle
launch.
The MRF clutch thus may
replace the existing torque
converters and therefore help
increase the fuel economy.
Schematic of a cylindrical MR Clutch
5.Aerospace
Magnetorheological
dampers are under
development for use in
military and commercial
helicopter cockpit seats, as
safety devices in the event
of a crash.
When no
magnetic field,
low viscosity
of MR fluid
When magnetic
field applied,
high viscosity
of MR fluid
Conclusion
 Relatively new technology has caught on quickly and is
replacing century-old methods for developments.
 Used not only in typical machined applications, but in
house hold things and many industries.
 As material and industrial technology advances faster ,
longer component life and good products will be
achievable.
References
 www.wikipedia.org/magneticfluid.index.
 www.powershow.com/magnetorheologicalfluid.ppt/
 Article:  (History of Magnetorheological Finishing Daniel C. Harris, Naval Air
Systems Command).

(THE BEHAVIOUR OF MAGNETORHEOLOGICAL LUIDS IN SQUEEZE MODE
By SAIFUL AMRI BIN MAZLAN, School of Mechanical and Manufacturing
Engineering Faculty of Engineering and Computing ,Dublin City University)