3. Introduction
A magneto rheological 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,
4. Introduction
Magneto rheological shock absorber is a
material filled with magneto rheological fluid,
which is controlled by a magnetic field, usually
using an electromagnet. This allows the
damping characteristics of the shock absorber
to be continuously controlled by varying the
power of the electromagnet.
This type of shock absorber has several
applications, most notably in semi-active
vehicle suspensions which may adapt to road
conditions, as they are monitored through
sensors in the vehicle, and in prosthetic limbs.
5. Introduction
A smart fluid is a fluid whose
properties can be changed by
applying an electric field or a magnetic
field.
6. Working Principle
The magnetic particles which are
typically micrometer or nano meter scale
When a magnetic field is applied,
however, the microscopic particles
(usually in the 0.1–10 µm range) align
themselves along the lines of magnetic
flux
7. Working Principle
Due to this magnetic flux viscosity of
magneto rheological fluid gets
increases and helps to reduce shock.
Thus it acts as a Bingham plastic.
8. Modes of Operation
1) Flow Mode
The fluid is located between a pair of
stationary poles.
The resistance to the fluid flow is
controlled by modifying the magnetic field
between the poles, in a direction
perpendicular to the flow Devices using
this mode of operation include servo
valves, dampers, shock absorbers and
actuators.
9.
10. Modes of operations
2) Shear Mode
The fluid is located between a pair of
moving poles (translation or rotation
motion).
The relative displacement is parallel to
the poles. The apparent viscosity, and thus
the “drag force” applied by the fluid to the
moving surfaces can be controlled by
modifying the magnetic field between the
poles. Devices using this mode of
operation include clutches, brakes, locking
devices .
11.
12. Modes of Operation
3) Squeeze Flow Mode
The fluid is located between a pair of
moving poles.
The relative displacement is
perpendicular to the direction of the fluid
flow .
The compression force applied to the
fluid is varying periodically.
Displacements are small compared to
the other modes but resistive forces are
15. Advantages
It can used in Dampers & shock
absorber.
It is high quality fluid.
16. Disadvantages
It is not insurmountable
It is expensive.
Fluids are subject to thickening after
prolonged use and need replacing.
17. Future Scopes
The U.S. Army Research Office is
currently funding research into using
MR fluid to enhance body armor
Can be used in the construction of the
Hubble Space Telescope's corrective
lens.
Magneto rheological dampers are
under development for use in military
and commercial helicopter cockpit
seats, as safety devices in the event
of a crash
