Electromagnetic Shock Absorber

ELECTROMAGNETIC SHOCK ABSORBER
PROJECT REPORT
Submitted by
AJITH ARAVIND (AXAKEME002)
JESBIN JOHNSON (AXAKEME018)
VINOD K J (AXAKEME035)
VISHNU T SAJEEVAN (AXAKEME038)
in partial fulfillment for the award of the degree
of
BACHELOR OF TECHNOLOGY
in
MECHANICAL ENGINEERING
AXIS COLLEGE OF ENGINEERING & TECHNOLOGY,
AMBANOLY
2014

Project ’14 Electromagnetic Shock Absorber
ii
Dept of Mechanical Engg AXISCET
DEPARTMENT OF MECHANICAL ENGINEERING
CERTIFICATE
This is to certify that the Project titled
ELECTROMAGNETIC SHOCK ABSORBER
was prepared and presented by
AJITH ARAVIND (AXAKEME002)
JESBIN JOHNSON (AXAKEME018)
VINOD K J (AXAKEME035)
VISHNU T SAJEEVAN (AXAKEME038)
of the Eighth Semester Mechanical Engineering
in partial fulfillment of requirement for the award of
Degree of Bachelor of Technology in Mechanical Engineering under the
University of Calicut during the year 2010-2014
PROJECT GUIDE HEAD OF THE DEPARTMENT

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ACKNOWLEDGEMENT
We express our deep sense of gratitude and indebtedness to Asst Prof. Manu
Mohan Nair, Head of Department, Mechanical Engineering for his valuable
advice, constant encouragement, for being our internal guide in the design and
implementation of our project, constructive criticism during the course of the
project and also during the preparation of this manuscript.
We are highly indebted to the staff members of Mechanical Department,
especially Asst.Professors Jineesh.V.V, Clint.K.S, Joffin Jose, Midhun Joy,
Ridhik Radh for their wholehearted support and co-operation.
We also express our indebt thanks to our Mechanical workshop
superintendent Mr.Velayudhan, and trade instructors Mr.Sooraj and Mr.Jacob, for
their helpful mind during the work.
We also express our sincere thanks to all the classmates for their support
and co-operation in completing the project work.
Above all, we should express our supreme gratitude to almighty God.

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ABSTRACT
A shock absorber in common parlance (or damper in technical use) is a
mechanical device designed to smooth out or damp sudden shock impulse and
dissipate kinetic energy. It is analogous to a resistor in an electric circuit. Shock
absorbers must absorb or dissipate energy. One design consideration, when
designing or choosing a shock absorber is where that energy will go.
Magnetic shock absorber is an advanced area that can be used to absorb
the heavy shock loads which will occur in automobiles. In magnetic shock
absorber, repulsive forces from same poles of permanent magnets/electro magnets
are used for absorbing the heavy shock loads. Two magnets are fixed permanently
in top and bottom end cover of the magnetic shock absorber. Another one magnet
is mounted on the movable rod. This magnet will move up and down vertical
direction with the rod. All magnets are fixed like same poles are facing each other.
This will help to create the repulsive force for absorbing the shock.
Top end cover is fixed with body of the vehicle by using bolt connections
and movable rod is fixed at the end with the axle of the vehicle. When the vehicle
experiences the sudden shock, movable rod slides vertically inside the cylinder
along with the magnet. The same poles of the fixed and movable magnets are
creating the strong repulsive force. This repulsive force is used for absorbing the
heavy shock load and magnetic shock absorber will act as a damping device for
vehicle. When the heavy shocking load decreases, the movable magnet comes into
the original position. The variable magnet movement depends on the magnitude of
the shock load. In this way, this magnetic shock absorber absorbs the heavy load
in the vehicle.
High grade “Neodymium” [NdFeB] materials are available, having good
magnetic property. Along with stainless steel can used for other components in
the magnetic shock absorber. This non magnetic stainless steel will not disturb the
magnetic field and magnets inside the shock absorber. The non-magnetic material
will hold the magnet in both the sides.

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TABLE OF CONTENT
CHAPTER TITLE PAGE
ACKNOWLEDGEMENT iii
ABSTRACT iv
LIST OF TABLES vii
LIST OF FIGURES vii
1 INTRODUCTION 1
1.1 Different shock absorbers in use 3
1.2 Types of suspension system 5
1.2.1 Rigid axle front suspension 5
1.2.2 Independent front suspension 6
1.2.3 Torque rod 8
1.2.4 Stabilizer 8
1.3 Permanent magnetic shock absorber 8
2 LITERATURE REVIEW 12
2.1 Investigations of shock absorber 12
2.2 MR Fluids 17
2.3 Concept & modelling eddy current damper 18
2.4 Design considerations 20
2.4.1 Manufacturability 20
2.4.2 Cost 20
2.4.3 Durability 21
2.4.4 Heat dissipation 21
2.4.5 Assembly/Disassembly considerations 21
2.4.6 Sealing 21
2.5 Theoretical Approaches 22
3 PROBLEM STATEMENT 25

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4 COMPONENTS AND DESCRIPTION 27
4.1 Mechanical components 27
4.1.1 Frame structure 27
4.1.2 Cylinder and piston 27
4.1.3 Permanent magnet 30
4.1.4 Coil spring 35
4.2 Electrical components 38
4.2.1 Battery 38
4.2.2 Electromagnet 40
5 RESULTS AND DISCUSSIONS 52
5.1 Electromagnetic force 53
5.2 Repulsive force between magnets 54
5.3 Critical damping coefficient 55
5.4 Design of shock absorber 55
5.5 Billing 57
6 SCOPE AND FUTURE OF PROJECT 58
REFERENCES 60

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LIST OF TABLES
Table Number TITLE PAGE
4.1 Physical properties of neodymium magnet 34
4.2 Battery specifications 39
5.1 Billing table 57
LIST OF FIGURES
Figure Number TITLE PAGE
1.1 Telescopic shock absorber 2
1.2 Schematic Representation 9
1.3 Magnetic Shock Absorber with Regeneration11
2.1 Force vs. Peak Velocity at A Constant
Frequency of 20 Hz 14
2.2 MR Effects 18
2.3 Velocity Profiles across the Annular Duct 18
2.4 Illustration of Arrangement
of Magnetic Field 19
4.1 Cylinder top view 28
4.2 Cylinder top and cover 28
4.3 Piston 29
4.4 Neodymium magnet 32
4.5 Coil spring 36
4.6 Battery 39
4.7 Magnetic wire 41
4.8 Typical EI lamination 46
4.9 Electromagnet 49
5.1 Shock absorber attached on frame 52
5.2 Repulsion of magnets 53
5.3 Piston and cylinder view 55
5.4 Damper 56

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CHAPTER I
INTRODUCTION
A shock absorber in common parlance (or damper in technical use) is a
mechanical device designed to smooth out or damp sudden shock impulse and
dissipate kinetic energy. It is analogous to a resistor in an electrical circuit.
Shock absorbers must absorb or dissipate energy. One design
consideration, when designing or choosing a shock absorber is where that energy
will go. In most dashpots, energy is converted to heat inside the viscous fluid. In
hydraulic cylinders, the hydraulic fluid will heat up. In air cylinders, the hot air is
usually exhausted to the atmosphere. In other types of dashpots, such as
electromagnetic ones, the dissipated energy can be stored and used later.
Shock absorbers are an important part of automobile and motorcycle
suspensions, aircraft landing gear, and the supports for many industrial machines.
Large shock absorbers have also been used in structural engineering to reduce the
susceptibility of structures to earthquake damage and resonance.
Shock absorbers, linear dampers, and dashpots are devices designed to
provide absorption of shock and smooth deceleration in linear motion
applications. They may be mechanical (e.g., elastomeric or coil spring) or rely on
a fluid (gas, air, hydraulic), which absorbs shock by allowing controlled flow from
outer to inner chamber of a cylinder during piston actuation. In conventional
shock absorbers the piston rod is typically returned to the unloaded position with a
spring. Shock absorbers typically contain either a fluid or mechanical dampening
system or a return mechanism to the unengaged position. They vary from small
device application to large industrial and civil engineering uses. Linear dampers is
an inclusive term that can be applied to many forms of dashpots and shock
absorbers; typically used for devices designed primarily for reciprocating motion
attenuation rather than absorption of large shock loads. Dashpots are typically
distinct in that while they use controlled fluid flow to dampen and decelerate
motion, they do not necessarily incorporate an integral return mechanism such as
a spring. Dashpots are often relatively small, precise devices used for applications.

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Fig No 1.1 Telescopic Shock Absorber
Shock absorbers or damper types for shock absorbers, linear dampers and
dashpots can be hydraulic, air, gas spring, or elastomeric. The absorption or
damping action can be compression or extension. Important parameters to
consider when searching for shock absorbers, linear dampers and dashpots include
absorber stroke, compressed length, extended length, maximum force, and
maximum cycles per minute. Absorber or spring stroke is difference between fully
extended and fully compressed position. Compressed length is the minimum
length of shock (compressed position). Extended length is the maximum length of
shock (extended position). The maximum rated force for shock absorber or
damper, referred to as the force. The maximum cycles per minute are the rated
frequency of compression or extension.
Important physical specifications to consider when searching shock
absorbers, linear dampers and dashpots include the cylinder diameter or maximum
width, the rod diameter, mounting, and body material. The cylinder diameter or
maximum width refers to the desired diameter of housing cylinder. The rod
diameter refers to the desired diameter of extending rod. Mounting choices
include ball and socket, rod end, clevis, eyelet, tapered end, threaded, and bumper

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or rod end unattached. Choices for body materials include aluminum, steel,
stainless steel, and thermoplastic.
Common features for shock absorbers, linear dampers and dashpots
include adjustable configuration, reducible, locking, and valve. An adjustable
configuration allows the user to fine tune desired damping, either continuously or
at discrete settings. A reducible shock absorber, linear damper or dashpot has an
adjustment style for gas shocks in which gas is let out to permanently reduce force
capacity. In a locking configuration the position can be locked at ends or in the
middle of stroke. Valves can be included for fluid absorbers, a valve or port,
which can be used to increase or decrease fluid volume or pressure.
1.1 DIFFERENT SHOCK ABSORBERS IN USE
1. There are several commonly-used approaches to shock absorption:
2. Hystersis of structural material, for example the compression of rubber
disks, stretching of rubber bands and cords, bending of steel springs, or
twisting of torsion bars. Hysteresis is the tendency for otherwise elastic
materials to rebound with less force than was required to deform them.
Simple vehicles with no separate shock absorbers are damped, to some
extent, by the hysteresis of their springs and frames.
3. Dry friction as used in wheel brakes, by using disks (classically made of
leather) at the pivot of a lever, with friction forced by springs. Used in
early automobiles. Although now considered obsolete, an advantage of this
system is its mechanical simplicity; the degree of damping can be easily
adjusted by tightening or loosening the screw clamping the disks, and it
can be easily rebuilt with simple hand tools. A disadvantage is that the
damping force tends not to increase with the speed of the vertical motion.
4. Solid state, tapered chain shock absorbers, using one or more tapered, axial
alignment(s) of granular spheres, typically made of metals such as nitinol,
in a casing.

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5. Fluid friction, for example the flow of fluid through a narrow orifice
(hydraulics), constitutes the vast majority of automotive shock absorbers.
An advantage of this type is that using special internal valving the absorber
may be made relatively soft to compression (allowing a soft response to a
bump) and relatively stiff to extension, controlling “jounce”, which is the
vehicle response to energy stored in the springs; similarly, a series of
valves controlled by springs can change the degree of stiffness according
to the velocity of the impact or rebound. Some shock absorbers allow
tuning of the ride via control of the valve by a manual adjustment provided
at the shock absorber. In more expensive vehicles the valves may be
remotely adjustable, offering the driver control of the ride at will while the
vehicle is operated. The ultimate control is provided by dynamic valve
control via computer in response to sensors, giving both a smooth ride and
a firm suspension when needed. Many shock absorbers contain
compressed nitrogen, to reduce the tendency for the oil to foam under
heavy use. Foaming temporarily reduces the damping ability of the unit.
Another variation is the magneto rheological damper which changes its
fluid characteristics through an electromagnet.
6. Compression of a gas, for example pneumatic shock absorbers, which can
act like springs as the air pressure is building to resist the force on it. Once
the air pressure reaches the necessary maximum, air dashpots will act like
hydraulic dashpots. In aircraft landing gear air dashpots may be combined
with hydraulic damping to reduce bounce. Such struts are called oleo struts
(combining oil and air).
7. Magnetic effects. Eddy current dampers are dashpots that are constructed
out of a large magnet inside of a non-magnetic, electrically conductive
tube.
8. Inertial resistance to acceleration, for example prior to 1966 the Citroen
2cv had shock absorbers that damp wheel bounce with no external moving
parts. These consisted of a spring-mounted 3.5 kg (7.75 lb) iron weight
inside a vertical cylinder and are similar to, yet much smaller than versions
of the tuned mass dampers used on tall buildings

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9. Composite hydro-pneumatic devices which combine in a single device
spring action, shock absorption, and often also ride-height control, as in
some models of the Citroen automobile.
10. Conventional shock absorbers combined with composite pneumatic
springs with which allow ride height adjustment or even ride height
control, seen in some large trucks and luxury sedans such as certain lincoln
and most land rover automobiles. Ride height control is especially
desirable in highway vehicles intended for occasional rough road use, as a
means of improving handling and reducing aerodynamic drag by lowering
the vehicle when operating on improved high speed roads.
1.2 TYPES OF SUSPENSION SYSTEM
1.2.1 RIGID AXLE FRONT SUSPENSION
It shows a typical rigid axle font wheel suspension. This type of suspension was
universally used before the introduction of independent front wheel suspension. It
may use either two longitudinal leaf spring, or on transverse spring, usually in
conjunction with shock absorbers. These assemblies are mounted similarly to rear
leaf spring suspensions.
In this type of suspension, the front wheel hubs rotate on anti – fiction
bearings on steering spindles, which are attached to the steering knuckles. To
permit the wheels to be tuned by the steering gear, the steering spindle and the
steering knuckle assemblies are hinged on the axle ends. The pin that forms the
pivot of this hinge is usually referred to as the kingpin or steering knuckle pin.
Where the forked portion is integral with the steering knuckle and fits over the end
of the axle, the construction is known as reverse Elliot. In Elliot type construction,
the ends of the axle are forked to hold the steering knuckle extension between the
ends.

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1.2.2 INDEPENDENT FRONT SUSPENSION
In the independent type of front suspension, a coil, torsion bar or leaf spring
independently supports each front wheel. Almost all the passenger cars now use
the independent front suspension, in which the coil spring arrangement is the most
common.
There are three types of coil spring front suspension:
1. In the first type, the coil spring is located in between the upper and lower
control arms. The lower control arm has one point attachment to the car
frame.
2. In the second type, the coil spring is located in between the upper and
lower control arms. The lower arms have two points to attachment to the
car frame.
3. In the third type, the coil spring is between the upper control arm and
spring tower or housing that is part of the front – end sheet – metal work.
Other types of front suspension, besides coil spring type, are also in use.
The twin I – beam construction is another type, used on some models of Ford
trucks. Each front wheel is supported at the end by a separate I – beam. The ends
of the I – beams are attached to the frame by pivots.
The wheel ends of the two I – beams are attached to the frame by radius
arms, which prevent backward or forward movement of the wheels. This type of
suspension provides more flexibility. Single I – beam front suspension is used in
larger trucks. The I-beam has a hole in each end through which a kingpin is
assembled to hold the steering knuckle in place. Each end of the I-beam is
supported by a leaf spring.
In this type of suspension system, a steel rod, known as a torsion bar, act
as a spring to hold the upper and lower control arms parallel under load. The front
end of the rod is of hexagonal shape to fit tightly into an opening in the lower

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control arm. Its rear reaction is also of the hexagonal shape to fit tightly into an
opening in an anchor attached to the frame cross member.
A seal hides the hexagonal shaped end of the torsion bar. The torsion bar
twisted due to the forces on the wheel assembly outer end of the lower control
arm. The torsion bar is designed to balance these forces so that the lower arm is
kept at a designated height. The height can be adjusted by a tightening mechanism
at the anchor end, which twists the rod by means of an adjusting bolt and swivel.
A strut rod is used to keep the suspension in alignment.
This type of suspension is able to cushion road shocks by causing the
lower arm to twist the torsion bar. When the wheels are no larger under stress, the
arm returns to normal. It simplifies the independent front suspensions using coil,
torsion bar and leaf spring. Basically, the system is known as parallelogram type
independent front suspension. It consists of an upper and lower link connected by
the stub axle carrier. In general, the lower link is larger than the upper and they
may not be parallel. This arrangement maintains the track width as the wheel rise
and fall and so minimize tyre wear caused by the wheel scrubbing sideways.
Strut and link type suspension system is particularly for integral body
construction, because the loading points are widely spaced. The normal top link is
replaced by a flexible, mounting, and a telescopic damper acts as the kingpin. This
system, known as the Mac Pherson system has little rolling action and absorbs
shocks readily.
Trailing arm independent front suspension maintains constant track and
wheel attitude with a slight change in wheelbase and caster angle. A coil spring is
attached to the trailing arm which itself is attached to the shaft carrying the wheel
hub. When the wheel moves up and down, it winds and unwinds the spring. A
torsion bar has also been used in certain designs in place of the coil spring.
In sliding type suspension system, the stub axle can move up and down as
well as rotate in the frame members. Track, wheel attitude and wheelbase remain
unchanged throughout the rise and fall of the wheel.
In vertical guide suspension system, the kingpin is attached directly to the
cross member of the frame. It can slide up and down, thus compressing and
expanding the springs.

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1.2.3 TORQUE ROD
The torque rod is used to maintain correct alignment of the axle with the frame. It
also serves to remove all the stresses on the springs. One end of the torque rod is
rigidly fixed to the axle or axle housing, and the other end is attached to the frame
by means of a pivoted mounting. The torque rod is also known as torque rod.
1.2.4 STABILIZER
A stabilizer or a sway bar, is necessarily is used in all independent front-end
suspension. It reduces the tendency of the vehicle to roll or tip on either side when
taking a turn. This tendency has been increased due to the use of softer springs
and independent front-end suspension.
A stabilizer is simply a bar of alloy steel with arms at each end connected
to the lower wishbone of the independent suspension or axle. It is supported in
bush bearings fixed to the frame, and is parallel to the cross member.
When both the wheels deflect up or down by the same amount, the
stabilizer bar simply turns in the bearings. When only one wheel deflects, then
only one end of the stabilizer moves, thus twisting the stabilizer bar, which acts as
a spring between the two sides of the independent suspension. In this way, the
stabilizer reduces heeling or tipping of the vehicle on curves.
1.3 PERMANENT MAGNET SYSTEM SHOCK ABSORBER
A permanent magnetic suspension apparatus for maintaining a spaced
relationship between a first movable member and a second fixed member, wherein
the motion of the movable member requires dampening, cushioning, stabilizing,
harmonic balancing, and/ or reflexive re-centring.
The suspension apparatus includes a plurality of sets of permanent
magnets located within a case, which is coupled to one of the members. The sets
of permanent magnets are coupled to an elongated support member, which is

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couple to the second member. The support member extends within the case, with
the support member and the case being adapted for relative axial movement.
The sets of permanent magnets are arranged in bidirectional repulsion
configuration with additional magnet fixed within the case. The sets of permanent
magnets are being moved relative to the fixed permanent magnets, such that the
magnetic forces of repulsion produced by the permanent magnets are increased in
response to relative movement between the support member and the case, creating
dampening, cushioning, stabilizing, harmonic balancing, and/or re-centring forces.
Fig No 1.2 Schematic Representation
In one embodiment, the control mechanism is coupled between the frame
of a vehicle and a wheel support assembly. The permanent magnetic suspension
apparatus, however, is for use with any type of equipment or machinery having a
movable and non-movable, or fixed, member. This includes, but is not limited to,
cars, trucks, motorcycles, scooters, all terrain vehicles, semi-tractors, semi-trailers,
and the like, as well as, but not limited to, industrial equipment and machinery,
hospital and office machinery and equipment, such as being coupled between the
frame of an office chair and the chair seat.
A regenerative electromagnetic shock absorber comprising: a linear
electromagnetic generator comprised of a central magnet array assembly
comprising a central magnet array comprised of a plurality of axially-aligned,
stacked cylindrical magnets having like magnetic poles facing one another, a
plurality of high magnetic permeability, high saturation magnetization, central

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cylindrical spacers positioned at each end of stacked central magnet array and
between adjacent stacked central magnets, and a magnet array support for
mounting magnets and spacers. An inner coil array comprising a plurality of
concentric cylindrical coil windings positioned adjacent to central spacers and
magnetic poles of central magnets, inner coil windings surrounding an outside
perimeter of central spacers. The inner coil array mounted on a movable coil
support, movable coil support providing for reciprocating linear motion of coil
array relative to magnet array.
And an outer magnet array assembly comprising an outer magnet array
comprised of a plurality of axially-aligned, stacked concentric toroidal magnets
having like magnetic poles facing each other, outer magnet array surrounding
inner coil array, stacked outer concentric magnets being aligned and positioned
essentially coplanar with stacked central cylindrical magnets with the magnetic
poles of outer magnets aligned with and facing opposing magnetic poles of central
cylindrical magnets, and a plurality of high permeability, high saturation
magnetization, outer concentric toroidal spacers positioned at each end of stacked
outer magnet array and between adjacent stacked outer magnets, outer magnet
array assembly attached to magnet array support; wherein a predetermined
location, configuration and orientation of central magnet magnetic poles, central
spacers, inner coil windings, outer magnet magnetic poles and outer spacers
provide for superposition of a radial component of a magnetic flux density from a
plurality of central and outer magnets to produce a maximum average radial
magnetic flux density in the inner coil windings; and a voltage conditioning circuit
electrically connected to coil windings, voltage conditioning circuit providing an
output voltage and output current to an electrical load.

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Fig No 1.3 Magnetic Shock Absorber with Regeneration

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CHAPTER II
LITERATURE REVIEW
Andrzej Milecki , Miko" Aj Hauke, 2012,Application Of Magnetorheological
fluid In Industrial Shock Absorbers, discussed: Magnetorheological (MR) fluid,
which is capable of controlling the stopping process of moving objects, e.g. on
transportation lines. The proposed solution makes it possible to adjust the braking
force (by electronic controller) to the kinetic energy of the moving object . The
paper presents an overview of passive shock absorbers. Next, the design concept
of a semi- active shock absorber with the MR fluid is proposed. Theoretically the
optimal breaking process occurs when the breaking force is constant on the whole
stroke of the absorber.
The passive shock absorbers which are in use now do not guarantee this.
The braking force of these absorbersis not constant, and, as a result, the stopping
process is not optimal. Therefore there is a need for improvement. Recently, semi-
active devices, also called ‘‘intelligent’’ devices, have been proposed for the
damping of vibrations and oscillations.The parameters of these devices, like the
movement opposite force, can be continuously changed with minimal energy
requirements. They utilise electrorheological (ER) or magnetorheological (MR)
fluids. Such fluids can be quite attractive for industrial applications in the stopping
of moving elements on production lines. Compared to conventional
electrorheological solutions, MR devices are stronger and can be operated directly
from low-voltage power supplies this is why MR fluids are much more often used.
2.1 INVESTIGATIONS OF SHOCK ABSORBER WITH
MAGNETORHEOLOGICAL FLUID
A bypass valve with a cylindrical gap was mounted on the interface plate. The
complete shock absorber is approximately 310 mm long and contains
approximately 0.05 dm3 of the MR fluid. An electro-hydraulic servo drive was
applied to control the velocity of the piston. The MR shock absorber and the drive
were attached to a plate that was mounted on a strong floor. A Linear Variable

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Differential Transducer (LVDT) was used to measure the displacement (linearity
0.5%) and an HBM 5 kN transducer was used to measure the braking force. The
measured signals (force and displacement) were transformed into a digital form by
a 16-bit analogue/digital (ADC0 and ADC1) converter placed in an input/output
card, and then sent to the computer and recorded in its memory. The displacement
signal was differentiated in order to obtain the piston velocity. The same computer
was used to control the electro-hydraulic servo system velocity (DAC1) and the
MR shock absorber coils current (DAC0).
Babak Ebrahimi , Mir Behrad Khamesee , M. Farid Golnaraghi, 2008,Design And
Modeling Of A Magnetic Shock Absorber Based On Eddy Current Damping
Effect, studied: Eddy currents are generated in a conductor in a time-varying
magnetic field. They are induced either by the movement of the conductor in the
static field or by changing the strength of the magnetic field, initiating motional
and transformer electromotive forces (emfs), respectively. Since the generated
eddy currents create a repulsive force that is proportional to the velocity of the
conductor, the moving magnet and conductor behave like a viscous damper.
Graves et al have derived a mathematical representation for eddy current dampers,
based on the motional and transformer emf, and have developed an analytical
approach to compare the efficiency of the dampers in terms of these two sources.
For more than two decades, the application of eddy currents for damping purposes
has been investigated, including magnetic braking systems , vibration. Control of
rotary machinery, structural vibration suppression , and vibration isolation
enhancement in levitation systems. The newly developed analytical model is used
to design high-performance dampers for a variety of applications.
The damping characteristic of the proposed system can be easily changed
by either re-positioning the conductor or choosing the appropriate conductor size
and the air-gap distance between the magnets. The novel magnetic spring–damper
described in this article is a non-contact device with adjustable damping
characteristics,no external power supply requirement and suitable for different
vibrational structures for high accuracy and simple implementation. The proposed
magnetic spring damper can be modified in terms of size, material , and
topological design for different applications. Future work might involve extending

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the magnetic spring–damper design for vehicle suspension systems, since the
damper is oil free, inexpensive, requires no external power, and is simple to
manufacture.
Fig No 2.1 Peak Force vs. Peak Velocity at A Constant Frequency of 20 Hz
Alberdi-Muniain , N. Gil-Negrete , L. Kari, 2012,Direct Energy flow
Measurement In Magneto-Sensitive Vibration Isolator Systems, learned: The
effectiveness of highly non-linear, frequency, amplitude and magnetic field
dependent magneto-sensitive natural rubber components applied in a vibration
isolation system is experimentally investigated by measuring the energy flow into
the foundation. The energy flow, including both force and velocity of the
foundation, is a suitable measure of the effectiveness of a real vibration isolation
system where the foundation is not perfectly rigid. The vibration isolation system
in this study consist s of a solid aluminium mass supported on four magneto-
sensitive rubber components and is excited by an electro-dynamic shaker while
applying various excitation signals, amplitudes and positions in the frequency
range of 20–200 Hz and using magneto sensitive components at zero-field and at
magnetic saturation. The energy flow through th e magneto-sensitive rubber
isolators is directly measured by inserting a force transducer below each isolator
and an accelerometer on the foundation close to each isolator.
Bart.L.J.Gysen, Johannes.J.H.Paulides, Jeroen.L.G.Janssen, 2010, Active
Electromagnetic Suspension System For Improved Vehicle Dynamics studied:

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Due to the change in vehicle concepts to the more electric car, the suspension
system becomes ever more important due to changes in the sprung and unsprung
masses. Active electromagnetic suspension systems can maintain the required
stability and comfort due to the ability of adaptation in correspondence with the
state of the vehicle. Specifications are drawn from on-and off road measurements
on a passive suspension system, and it can be concluded that, for ARC, a peak
force of 4kN and an RMS force of 2kN (dutycycleof100%) are necessary for th
front actuators. Furthermore, the necessary peak damping power is around 2kW;
however, the RMS damping power is only 16W during normal city driving. The
maximum bound and rebound strokes are 80 and 58mm, respectively. The on road
measurements, which are mimicked on a quarter car setup by means of
electromagnetic actuation, a good tracking response, and measurement of the
frequency response of the tubular actuator, prove the dynamic performance of the
electromagnetic suspension system
Georgios Tsampardoukas, Charles W.Stammers, Emanuele Guglielmino, 2008,
Hybrid Balance Control Of A Magnetorheological Truck Suspension, discussed:
The paper concerns an investigation into the use of controlled magnetorheological
dampers for a semi active truck suspension. A control strategy targeted to reduce
road damage without penalizing driver comfort is presented. A half truck model is
employed and system performance investigated via numerical simulation. A
balance control algorithm (variable structure type algorithm) based on dynamic
tyre force tracking has been devised. Algorithm robustness to parametric
variations as well as to real life implementation issues such as feedback signals
noises are investigated as well. The magnitude of total road damage reduction
(over three axles)on a simulated random road varies with vehicle speed. The
reduction was found to be 6% at 7.5m/s, 19% at 17.5m/s and 9% at 25m/s.
Kirk T. McDonald, Joseph Henry Laboratories, Princeton University, Princeton,
NJ08544 (April14,2012)Magnetic Damping discussed: When a conductor moves
through a non uniform, external magnetic field, the magnetic flux varies through
loops fixed inside the conductor, so an electromotive force is induced around the
loops, according to Faraday’s law (in the rest frame of the conductor), and eddy

16
currents flow. The Lorentz force on these eddy currents, due to the external
magnetic field, opposes the motion, and one speaks of magnetic braking/damping.
This effect is (ultra) relativistic, being of order v2/c2, where v is the speed of the
conductor and c is the speed of light in vacuum. While such relativistic effects are
generally small for “ordinary” velocities, the eddy current density obeys J=σE,
where the conductivity σf or good conductors approaches c2/v2 when measured in
Gaussian units, such that eddy current braking is a rare example of an important
(ultra) relativistic correction at low velocities. In the present problem the magnetic
field is spatially uniform, so the magnetic flux through a moving loop does not
change, and no eddy currents develop. Yet, there exists a very weak magnetic
damping effect.
Zekeriya Parlak, Tahsin Engin, Ismail Çallı, 2012, Optimal Design Of MR
Damper Via Finite Element Analyses Of Fluid Dynamic And Magnetic Field,
studied: The purpose of the study was to optimize MR damper geometrically in
accordance with two objectives, target damper force as 1000N and maximum
magnetic flux density. The optimization studies were carried out by finite element
method using electromagnetic and CFD tools of ANSYSv12.1. The FEM analyses
were employed to get desired optimal values in ANSYS Goal Driven
Optimization tool. Values of optimal of the design parameters of the MR damper
were searched between lower and upper boundaries in both electromagnetic and
CFD analyses. The parameters were geometrical magnitudes, current excitation
and yield stress. In the electromagnetic analysis gap width, flange length, gap
length, piston head housing thickness, radius of piston core, the number of coil
turns and the applied current were selected as design parameters to be able to get
maximum magnetic flux density. The values were used in CFD analysis to obtain
damper force under optimal conditions

17
2.2 MR FLUIDS
When a magnetic field is applied to the fluid, particles in the fluid form
chains, and the suspension becomes like a semi-solid material in a few
millisecond. Under the magnetic field, an MR fluid behaves as a non-Newtonian
fluid with controllable viscosity. However, if the magnetic field is removed, the
suspension turns to a Newtonian fluid and the transition between these two phases
is highly reversible, which provides a unique feature of magnetic field
controllability of the flow of MR fluids. The chains form causes about 50 kPa of
yield stress depending on type of MR fluids in a few millisecond, the case creates
a resistance against the fluid flow. If a force is applied on the chains form, the
shape of the form changes in terms of magnitudes of the force and magnetic field.
The pressure reaction on MR fluid is called ‘‘MR effect’’. In figure as can be seen
that the particles are scattered randomly in the liquid carrier, when magnetic field
applied, the particle array in the direction of the magnetic flux lines to resist the
flow, and the chains form is changed in term of force applied to the particles.
Fig No 2.2 MR Effect
Magnetic field in the gap, the fluid acts like a rigid body below dynamic
yield stress considering the Bingham plastic model. This plug region is called the
pre-yield. In the pre-yield region, the local shear stresses have not yet exceeded

18
the dynamic yield stress. When the local shear stresses exceed the dynamic yield
stress, these regions are called the post-yield region and then the fluid acts like a
viscous fluid. The pre- and post-yield regions are shown in figure with the
velocity profile. As can be seen in figure, the velocity profile is divided into three
regions.
Fig No 2.3 Velocity Profiles Across the Annular Duct
Lei Zuo, Xiaoming Chen, Samir Nayfeh, 2011,Design And Analysis Of A New
Type Of Electromagnetic Damper With Increased Energy Density, learned:
2.3 CONCEPT AND MODELLING OF A NEW EDDY CURRENT
DAMPER
In this section, we first present the concept of the proposed eddy current dampers,
and then derive an analytical model for its damping coefficient.
Concept Illustration: Alternative Arrangement of Magnetic Poles.
It is a common practice in the design o transformers or electromagnetic
motors to use laminated steel to reduce the eddy current losses. The reason is that
by splitting the conductor, we can increase the electrical resistance of the current
loops. In an eddy current damper, we would like to reduce the loop electrical
resistance; that is why the area of conductors is usually several times larger than
the area of the magnetic field. Inspired by the approach of “splitting the
conductor” to reduce the eddy current in transformer design, we can “split the
magnets” to increase the eddy current via alternating the magnetic poles. To
illustrate this idea, consider two extreme cases as follows. Figure1 as how’s a
moving conductor in a uniform magnetic field of the same width. In figure the
magnetic field is split into two with alternative pole directions. When the

19
conductor is moving at position as shown in the figure, instantaneous electric
charges are induced in both cases, as indicated in figure. However, eddy current
loop and damping exist only in second case, but not in first case. It is similar to
two identical batteries connected
Fig No 2.4 Illustration of two types of arrangements of magnetic field for eddy
current dampers: case a uniform magnetic field and case b alternating magnetic
field
R. Zalewski , J. Nachman , M. Shillor , J. Bajkowski, 2013, Dynamic Model For
A Magnetorheological Damper, discussed: Lumped mass thermo-mechanical
model for the dynamics of a damper filled with a magnetorheological fluid is
described, analyzed, and numerically simulated. The model includes friction and
temperature effects, and consists of a differential inclusion for the piston
displacements coupled with the energy balance equation for the temperature. The
fluid viscosity is assumed to be a function the temperature and electrical current,
which in practice may be used as the control variable. Numerical simulations of
the system behaviour are presented. In particular, the simulations of an initial
impact show how the subsequent oscillations can be effectively damped.

20
Michael James Atherden,2004, Formula Sae Shock Absorber Design, The
University Of Queensland, discussed:
2.4 DESIGN CONSIDERATIONS
To form accurate conclusions as to the feasibility of the production of a
customised set of dampers, certain design issues must first be taken into account.
The factors which require consideration include manufacturability, cost,
durability, heat dissipation, assembly and disassembly procedures and sealing.
2.4.1 Manufacturability
For the design of the new damper to be feasible, the design must be such that it
can be manufactured, preferably in house at the university. As expressed
previously, dampers require exacting tolerances to be adhered to if quality items
are to be produced. The mechanical engineering workshop has the ability to
machine parts to average accuracy, such that I believe it would be possible to
manufacture a set of dampers with the current tooling.
2.4.2 Cost
The overall cost of the dampers can be reduced if careful consideration is given to
the component designs. One area where potential savings exist over purchased
dampers is in assembly, with students being able to assemble to units when the
components have been manufactured. An actual costing analysis of the damper
production will be performed after the design has been presented.
In Formula SAE competition, teams are required to complete a cost report
based on the competition rules. To summarize, purchased items must be costed at
recommended retail price, regardless if the team received a discount from the
supplier. For a manufactured item however, the cost of the item includes the raw
cost of the material, the machining operations included and the labour to machine
and assemble the component. If the team were to manufacture its own set of
dampers, significant savings could be made to the final cost of the car, a figure
worth 30/100 points for the cost event.

21
2.4.3 Durability
Dampers need to be designed with durability in mind as they from the compliant
link between the suspension and the chassis. As dampers are usually one of the
most expensive items on the vehicle, it is beneficial to be able to re-use them. To
be able to reuse the dampers, they should be designed such that major components
do not wear to the point where replacement is necessary. This may mean
increasing the weight of some components to extend their fatigue life and exerting
higher tolerances on machined parts, both of which increase the cost of the
damper.
2.4.4 Heat Dissipation
Dampers produce a resistive force by passing oil through narrow passages. As
time passes, frictional forces within the fluid and damper mechanisms generate
heat which raises the temperature of the oil. Short term temperature variations will
affect the viscosity of the damper oil, in some cases drastically altering the
performance of the damper. Long term thermal cycling of oil eventually degrades
its performance as its chemical properties change, thus good heat dissipation
prolongs the life of the damper, requiring less frequent maintenance. Heat
dissipation away from dampers is usually left to the vehicle designer, who must
provide adequate airflow around the unit.
2.4.5 Assembly / Disassembly Considerations
As the damper consists of many smaller components, due consideration must be
given as to how the damper is going to be assembled or disassembled. Most
components are circular by nature and hence threads are prolific. Accessing these
threads, by virtue of being able to apply enough torque to tighten or loosen them,
must be considered.
2.4.6 Sealing
Dampers generate resistive forces by generate large internal pressures. To contain
the contents of the damper under these pressures, adequate sealing must be

22
provided. Static seals usually consist of rubber O-rings fitting into machined
groves with specific dimensions as to provide sufficient ‘squish’ to form a seal.
Another type of seal often found in dampers is the sliding seal. Sliding seals are
used around the piston, the main shaft and possibly in the external reservoir.
These sliding seals usually perform dual functions, providing both a sealing
surface and axial support for the particular component.
2.5 THEORETICAL APPROACHES
There are several commonly used approaches to shock absorption:
1. Hysteresis of structural material, for eg.
the compression of rubber disks stretching of rubber bands and
cords, bending of steel springs, or twisting of torsion bars. Hysteresis is
the tendency for otherwise elastic materials to rebound with less force than
was required to deform them. Simple vehicles with no separate shock
absorbers are damped, to some extent, by the hysteresis of their springs
and frames.
2. Dry friction as used in wheel brakes, by using disks (classically made
of leather) at the pivot of a lever, with friction forced by springs. Used in
early automobiles such as the Ford Model T, up through some British cars
of the 1940s. Although now considered obsolete, an advantage of this
system is its mechanical simplicity; the degree of damping can be easily
adjusted by tightening or loosening the screw clamping the disks, and it
can be easily rebuilt with simple hand tools. A disadvantage is that the
damping force tends not to increase with the speed of the vertical motion.
3. Solid state, tapered chain shock absorbers, using one or more tapered,
axial alignment(s) of granular spheres, typically made of metals such
as nitinol, in a casing.
4. Fluid friction, for example the flow of fluid through a narrow orifice
(hydraulics), constitutes the vast majority of automotive shock absorbers.
This design first appeared on Morsracing cars in 1902. One advantage of
this type is, by using special internal valving, the absorber may be made
relatively soft to compression (allowing a soft response to a bump) and

23
relatively stiff to extension, controlling "rebound", which is the vehicle
response to energy stored in the springs; similarly, a series of valves
controlled by springs can change the degree of stiffness according to the
velocity of the impact or rebound. Specialized shock absorbers for racing
purposes may allow the front end of a dragster to rise with minimal
resistance under acceleration, then strongly resist letting it settle, thereby
maintaining a desirable rearward weight distribution for enhanced traction.
Some shock absorbers allow tuning of the ride via control of the valve by
a manual adjustment provided at the shock absorber. In more expensive
vehicles the valves may be remotely adjustable, offering the driver control
of the ride at will while the vehicle is operated. The ultimate control is
provided by dynamic valve control via computer in response to sensors,
giving both a smooth ride and a firm suspension when needed. Many
shock absorbers are pressurized with compressed nitrogen, to reduce the
tendency for the oil to cavitate under heavy use. This causes foaming
which temporarily reduces the damping ability of the unit. In very heavy
duty units used for racing or off-road use, there may even be a secondary
cylinder connected to the shock absorber to act as a reservoir for the oil
and pressurized gas.
5. In electrorheological fluid damper, an electric field changes the viscosity
of the oil. This principle allows semi-active dampers application in
automotive and various industries.
6. Other principles use magnetic field variation magneto rheological
damper which changes its fluid characteristics through an electromagnet.
7. Compression of a gas, for example pneumatic shock absorbers, which can
act like springs as the air pressure is building to resist the force on it. Once
the air pressure reaches the necessary maximum, air shock absorbers will
act like hydraulic shock absorbers. In aircraft landing gear air shock
absorbers may be combined with hydraulic damping to reduce bounce.
Such struts are called oleo struts (combining oil and air).
8. Inertial resistance to acceleration, for example prior to 1966 the Citroën
2CV had shock absorbers that damp wheel bounce with no external

24
moving parts. These consisted of a spring-mounted 3.5 kg (7.75 lb) iron
weight inside a vertical cylinder and are similar to, yet much smaller than
versions of the tuned mass dampers used on tall buildings.
9. Composite hydropneumatic devices which combine in a single device
spring action, shock absorption, and often also ride-height control, as in
some models of the Citroën automobile.
10. Conventional shock absorbers combined with composite pneumatic
springs which allow ride height adjustment or even ride height control,
seen in some large trucks and luxury sedans such as certain Lincoln and
most Land Rover automobiles. Ride height control is especially desirable
in highway vehicles intended for occasional rough road use, as a means of
improving handling and reducing aerodynamic drag by lowering the
vehicle when operating on improved high speed roads.

25
CHAPTER 3
PROBLEM STATEMENT
The automobile chassis is mounted on the axles, not direct but through some form
of springs. This is done to isolate the vehicle body from the road shocks which
may be in the form of bounce, pitch, roll or sway. These tendencies give rise to an
uncomfortable ride and also cause additional stress in the automobile frame and
body. All the parts which perform the function of isolating the automobile from
the road shocks are collectively called a suspension system. It includes the
springing device used and various mountings for the same.
Broadly speaking, suspension system consists of a spring and a damper.
The energy of road shock causes the spring to oscillate. These oscillations are
restricted to a reasonable level by the damper, which is more commonly called a
shock absorber.
A springing device must be a compromise between flexibility and
stiffness. Springs are placed between the road wheels and the body. When the
wheel comes across a bump on the road, it rises and deflects the spring, thereby
storing energy therein. On releasing, due to the elasticity of the spring material, it
rebounds thereby expending the stored energy. In this way springs starts vibrating,
of course, with amplitude decreasing gradually on account of internal friction of
the spring material and friction of the suspension joints, till vibrations die down.
The name Shock absorber is rather misleading since it is the spring and not
the shock absorber that initially absorbs the shocks. The ‘Shock Absorber’ absorbs
the energy of shock converted into vertical movement of the axle by providing
damping and dissipating the same into heat. Thus it merely serves to control the
amplitude and frequency of spring vibrations. It cannot support weight and has
zero resilience. Therefore, ‘Damper’ is a better term technically to describe the
‘Shock Absorber’.
In Magneto-rheological fluid type suspension system, fluid passes through
an orifice, which can be restricted by applying an electrical field across it. The
fluid consists of magnetically soft particles suspended in a synthetic fluid. When
current is applied to an electromagnetic coil inside the shock absorbers piston, the

26
resulting magnetic field changes the resistance of flow (rheology) of the fluid
which produces a very responsive and controllable damping action without any
valves. In the Magneto-suspension system, the damping effect is produced by the
theory of magnetic repulsion.
The fluidized damping system in the ‘Telescopic- shock absorbers’, is
replaced by the introduction of magnetic field. The magnets are placed in such a
way that, the mating surfaces are fitted with the same poles of magnet, thereby
producing the repulsive effect on the damper system

27
CHAPTER 4
COMPONENTS AND DESCRIPTION
The components of Electromagnetic shock absorbers are mainly categorized in to
two;
1. Mechanical Component
2. Electrical Component
4.1 MECHANICAL COMPONENTS
1. Frame Structure
2. Cylinder and Piston
3. Permanent Magnet
4. Coil Spring
4.1.1Frame Structure
It is just to support the shock absorber arrangement. The whole parts are fixed in
to this frame stand with suitable arrangement. It is made up of hollow MS pipes
which are cut and welded at desired positions.
4.1.2 Cylinder and Piston
A cylinder is the central working part of space in which a piston travels. It has two
heads. The top head accommodate the electromagnetic coil and core, which will
produce the repulsive force when excited. At the top head its just bored to increase
diameter, that will help to accommodate the electromagnet. Connection to the coil
is passed through the top hole that is drilled at the top.The material of cylinder is
usually mild steel, due to easy for machining

28
Fig.No 4.1 Cylinder top view
Fig. No 4.2 Cylinder and top cover

29
The piston is a cylindrical member of certain length which reciprocates
inside the cylinder. The diameter of the piston is slightly less than that of the
cylinder bore diameter and it is fitted to the top of the piston rod. It is one of the
important part which converts the pressure energy into repulsive force in this
shock absorber.
The piston is equipped with a ring suitably proportioned and it is relatively
soft rubber which is capable of providing good sealing with low friction at the
operating pressure. The purpose of piston is to provide means of conveying the
pressure.
Generally piston is made up of
1. Aluminium alloy-light and medium work.
2. Brass or bronze or CI-Heavy duty.
The piston is double acting type. The piston moves forward when the high-
pressure air is turned from the right side of cylinder. The piston moves backward
when high pressure acts on the piston from the left side of the cylinder. The
piston should be as strong and rigid as possible.
The efficiency and economy of the machine primarily depends on the
working of the piston. It must operate in the cylinder with a minimum of friction
and should be able to withstand the high compressor force developed in the
cylinder and also the shock load during operation.
The piston should posses the following qualities.
1. The movement of the piston not creates much noise.
2. It should be frictionless.
3. It should withstand high pressure.
Fig. No 4.3 Piston

30
4.1.3 Permanent Magnet
A magnet is a material or object that produces a magnetic field. This magnetic
field is invisible but is responsible for the most notable property of a magnet: a
force that pulls on other ferromagnetic materials like iron and attracts or repels
other magnets.
A permanent magnet is an object made from a material that is magnetized and
creates its own persistent magnetic field. An everyday example is a refrigerator
magnet used to hold notes on a refrigerator door. Materials that can be
magnetized, which are also the ones that are strongly attracted to a magnet are
called ferromagnetic (or ferrimagnetic). These include iron, nickel, cobalt, some
alloys of rare earth metals, and some naturally occurring minerals such as
lodestone. Although ferromagnetic (and ferrimagnetic) materials are the only ones
attracted to a magnet strongly enough to be commonly considered magnetic, all
other substances respond weakly to a magnetic field, by one of several other types
of magnetism. Ferromagnetic materials can be divided into magnetically "soft"
materials like annealed iron which can be magnetized but don't tend to stay
magnetized, and magnetically "hard" materials, which do. Permanent magnets are
made from "hard" ferromagnetic materials which are subjected to special
processing in a powerful magnetic field during manufacture, to align their internal
microcrystalline structure, making them very hard to demagnetize.
To demagnetize a saturated magnet, a certain magnetic field must be applied
and this threshold depends on coercivity of the respective material. "Hard"
materials have high coercivity whereas "soft" materials have low coercivity. An
electromagnet is made from a coil of wire which acts as a magnet when an electric
current passes through it, but stops being a magnet when the current stops. Often
an electromagnet is wrapped around a core of ferromagnetic material like steel,
which enhances the magnetic field produced by the coil.
The overall strength of a magnet is measured by its magnetic moment, or
alternately the total magnetic flux it produces. The local strength of the magnetism
in a material is measured by its magnetization

31
Magnetic field: The magnetic field (usually denoted B) is a vector field. The
magnetic field vector at a given point in space is specified by two properties:
1. Its direction, which is along the orientation of a compass needle.
2. Its magnitude (also called strength), which is proportional to how strongly
the compass needle orients along that direction.
In SI units, the strength of the magnetic field is given in teslas.
Magnetic moment: A magnet's magnetic moment (also called magnetic dipole
moment, and usually denoted μ) is a vector that characterizes the magnet's overall
magnetic properties. For a bar magnet, the direction of the magnetic moment
points from the magnet's south pole to its north pole, and the magnitude relates to
how strong and how far apart these poles are. In SI units, the magnetic moment is
specified in terms of A·m.
A magnet both produces its own magnetic field and it responds to
magnetic fields. The strength of the magnetic field it produces is at any given
point proportional to the magnitude of its magnetic moment. In addition, when the
magnet is put into an external magnetic field, produced by a different source, it is
subject to a torque tending to orient the magnetic moment parallel to the field. The
amount of this torque is proportional both to the magnetic moment and the
external field.
A magnet may also be subject to a force driving it in one direction or
another, according to the positions and orientations of the magnet and source. If
the field is uniform in space, the magnet is subject to no net force, although it is
subject to a torque.A wire in the shape of a circle with area A and carrying current
I is a magnet, with a magnetic moment of magnitude equal to IA.
Magnetization: The magnetization of a magnetized material is the local value of
its magnetic moment per unit volume, usually denoted M, with units A/m. It is a
vector field, rather than just a vector (like the magnetic moment), because
different areas in a magnet can be magnetized with different directions and
strengths (for example, because of domains, see below). A good bar magnet may

32
have a magnetic moment of magnitude 0.1 A·m2
and a volume of 1 cm3
, or
1×10−6
m3
, and therefore an average magnetization magnitude is 100,000 A/m.
Iron can have a magnetization of around a million amperes per meter. Such a large
value explains why iron magnets are so effective at producing magnetic fields.
The permanent magnet used in this shock absorber is Neodymium magnet.
A neodymium magnet (also known as NdFeB, NIB or Neo magnet), the most
widely used type of rare-earth magnet, is a permanent magnet made from
an alloy of neodymium, iron and boron to form the
Nd2Fe14B tetragonal crystalline structure. Developed in 1982 by General
Motors and Sumitomo Special Metals, neodymium magnets are the strongest type
of permanent magnet commercially available. They have replaced other types of
magnet in the many applications in modern products that require strong permanent
magnets, such as motors in cordless tools, hard disk drives and magnetic fasteners.
Some important properties used to compare permanent magnets
are: remanence (Br), which measures the strength of the magnetic
field; coercivity (Hci), the material's resistance to becoming demagnetized; energy
product (BHmax), the density of magnetic energy; and Curie temperature (TC), the
temperature at which the material loses its magnetism. Neodymium magnets have
higher remanence, much higher coercivity and energy product, but often lower
Curie temperature than other types. Neodymium is alloyed
with terbium and dysprosium in order to preserve its magnetic properties at high
temperatures. The table below compares the magnetic performance of neodymium
magnets with other types of permanent magnets.
Fig. No 4.4 Neodymium magnet

33
Neodymium magnets are graded according to their maximum energy product,
which relates to the magnetic flux output per unit volume. Higher values indicate
stronger magnets and range from N35 up to N52. Letters following the grade
indicate maximum operating temperatures.
Grades of Neodymium magnets:
1. N35-N52
2. 33M-48M
3. 30H-45H
4. 30SH-42SH
5. 30UH-35UH
6. 28EH-35EH
Neodymium magnet used is N4518, the easy availability and desirable
properties are the reason to choose it.
Property Neodymium
Remanence (T) 1–1.3
Coercivity (MA/m) 0.875–1.99

34
Relative permeability 1.05
Temperature coefficient of remanence (%/K) −0.12
Temperature coefficient of coercivity (%/K) −0.55..–0.65
Curie temperature (°C) 320
Density (g/cm3
) 7.3–7.5
CTE, magnetizing direction (1/K) 5.2×10−6
CTE, normal to magnetizing direction (1/K) −0.8×10−6
Flexural strength (N/mm2
) 250
Compressive strength (N/mm2
) 1100
Tensile strength (N/mm2
) 75
Vickers hardness (HV) 550–650
Electrical resistivity (Ω·cm) (110–170)×10−6
Table No 4.1 Physical properties of neodymium magnet

35
4.1.4 Coil Spring
A coil spring, also known as a helical spring, is a mechanical device, which is
typically used to store energy due to resilience and subsequently release it, to
absorb shock, or to maintain a force between contacting surfaces. They are made
of an elastic material formed into the shape of a helix which returns to its natural
length when unloaded.
Springs can be classified depending on how the load force is applied to
them:
1. Tension/Extension spring – the spring is designed to operate with
a tension load, so the spring stretches as the load is applied to it.
2. Compression spring – is designed to operate with a compression load, so
the spring gets shorter as the load is applied to it.
3. Torsion spring – unlike the above types in which the load is an axial force,
the load applied to a torsion spring is a torque or twisting force, and the
end of the spring rotates through an angle as the load is applied.
4. Constant spring - supported load will remain the same throughout
deflection cycle
5. Variable spring - resistance of the coil to load varies during compression
The suspension coil springs combined with shock absorbers prevent
undesired vertical movement of the vehicle and suppress jolts and vibrations. An
optimum design, an improved production process and a new type of primary
material make it possible to reduce the suspension coil spring weight by up to
50%.
One type of coil spring is a torsion spring: the material of the spring acts in
torsion when the spring is compressed or extended. The quality of spring is judged
from the energy it can absorb. The spring which is capable of absorbing the
greatest amount of energy for the given stress is the best one. Metal coil springs

36
are made by winding a wire around a shaped former - a cylinder is used to form
cylindrical coil springs.
A spring is an elastic object used to store mechanical energy. Springs are
usually made out of spring steel. Small springs can be wound from pre-hardened
stock, while larger ones are made from annealed steel and hardened after
fabrication. Some non-ferrous metals are also used including phosphor
bronze and titanium for parts requiring corrosion resistance
Fig. No 4.5 Coil Spring

37
This spring is obtained from a dismantled fluid shock absorber. Two end
caps are made with sheets two cover the ends and attach with the piston rod. The
properties of the spring taken are follows:
Material: spring steel
Wire dia= 10mm
Outer dia= 70mm
Inner dia= 50mm
Pitch= 23.2mm
No.of turns= 11
Length= 230mm
Stiffness of spring= 41.72×10^3 N/m

38
4.2 ELECTRICAL COMPONENTS
Electrical components are the other important parts of this system. These include:
1. Battery
2. Electromagnet
4.2.1 Battery
In isolated systems away from the grid, batteries are used for storage of
excess solar energy converted into electrical energy. The only exceptions are
isolated sunshine load such as irrigation pumps or drinking water supplies for
storage. In fact for small units with output less than one kilowatt. Batteries seem
to be the only technically and economically available storage means. Since both
the photo-voltaic system and batteries are high in capital costs. It is necessary that
the overall system be optimized with respect to available energy and local demand
pattern. To be economically attractive the storage of solar electricity requires a
battery with a particular combination of properties:
1. Low cost
2. Long life
3. High reliability
4. High overall efficiency
5. Low discharge
6. Minimum maintenance
a. Ampere hour efficiency
b. Watt hour efficiency
We use lead acid battery for storing the electrical energy from the solar
panel for lighting the street and so about the lead acid cells are explained below.
Since the shock absorber is installed in automobile, the easy power source
will be the rechargeable battery. It will recharge automatically when engine is on.
Usually 12V batteries are available for the use. And current will vary. Two
wheelers have 7A and four wheelers have 40A. We use a 7a battery for this
demonstration purpose.

39
Fig. No 4.6 Battery
Feature Data
Voltage 12V
Current 40A
Type 50B20R
Table No 4.2 Battery Specifications

40
4.2.2 Electromagnet
An electromagnet is a type of magnet in which the magnetic field is produced
by electric current. The magnetic field disappears when the current is turned off.
Electromagnets are widely used as components of other electrical devices, such
as motors, generators, relays, loudspeakers, hard disks, MRI machines, scientific
instruments, and magnetic separation equipment, as well as being employed as
industrial lifting electromagnets for picking up and moving heavy iron objects like
scrap iron.
An electric current flowing in a wire creates a magnetic field around the
wire, due to law. To concentrate the magnetic field, in an electromagnet the wire
is wound into a coil with many turns of wire lying side by side. The magnetic field
of all the turns of wire passes through the center of the coil, creating a strong
magnetic field there. A coil forming the shape of a straight tube (a helix) is called
a solenoid. Much stronger magnetic fields can be produced if a "core"
of ferromagnetic material, such as soft iron, is placed inside the coil. The
ferromagnetic core increases the magnetic field to thousands of times the strength
of the field of the coil alone, due to the high magnetic permeability μ of the
ferromagnetic material. This is called a ferromagnetic-core or iron-core
electromagnet.
The direction of the magnetic field through a coil of wire can be found
from a form of the right-hand rule. If the fingers of the right hand are curled
around the coil in the direction of current flow (conventional current, flow
of positive charge) through the windings, the thumb points in the direction of the
field inside the coil. The side of the magnet that the field lines emerge from is
defined to be the North Pole.
The main advantage of an electromagnet over a permanent magnet is that
the magnetic field can be rapidly manipulated over a wide range by controlling the
amount of electric current. However, a continuous supply of electrical energy is
required to maintain the field.

41
The cost of an electric machine depends upon its size and weight and
primarily on the weight of magnetic and conducting materials as these being most
costly ones. The weight of the magnetic materials is influenced by the size of the
magnetic circuit of the machine. To a great extent, the size and the weighty of the
machine depends upon the assigned values of specific magnetic loading, which is
limited by the saturation and core losses of the magnetic materials used in the
machine. However an increased value of specific magnetic loading could be
assigned for designing an electrical machine, provided the magnetic materials has
a comparatively higher saturation limit and lower core losses per kg of the
material.
The main components of electromagnets are insulated magnet wire and a
soft iron core. Magnet wire or enameled wire is
a copper or aluminium wire coated with a very thin layer of insulation. It is used
in the construction of transformers, inductors, motors, speakers, hard disk, head
actuators, potentiometers, electromagnets and other applications which require
tight coils of wire.
Fig No 4.7 Magnetic wire
The wire itself is most often fully annealed, electrolytically refined copper.
Aluminium magnet wire is sometimes used for large transformers and motors. An
aluminium wire must have 1.6 times the cross sectional area as a copper wire to

42
achieve comparable DC resistance. Due to this, copper magnet wires contribute to
improving energy efficiency in equipment such as electric motors. Smaller
diameter magnet wire usually has a round cross section. This kind of wire is used
for things such as electric guitar pickups. Thicker magnet wire is often square or
rectangular (with rounded corners) to provide more current flow per coil length.
Although described as "enameled", enameled wire is not, in fact, coated with
either a layer of enamel paint nor with vitreous enamel made of fused glass
powder. Modern magnet wire typically uses one to four layers (in the case of
quad-film type wire) of polymer film insulation, often of two different
compositions, to provide a tough, continuous insulating layer. Magnet wire
insulating films use (in order of increasing temperature range) polyvinyl formal
(Formvar), polyurethane, polyamide, polyester, polyester-polyimide, polyamide-
polyimide (or amide-imide), and polyimide. Polyimide insulated magnet wire is
capable of operation at up to 250°C. The insulation of thicker square or
rectangular magnet wire is often augmented by wrapping it with a high-
temperature polyimide or fiberglass tape, and completed windings are often
vacuum impregnated with an insulating varnish to improve insulation strength and
long-term reliability of the winding.
Other types of insulation such as fiberglass yarn with
varnish, aramid paper, kraft paper, mica, and polyester film are also widely used
across the world for various applications like transformers and reactors. In the
audio sector, a wire of silver construction, and various other insulators, such as
cotton (sometimes permeated with some kind of coagulating agent/thickener, such
as beeswax) and polytetrafluoroethylene (Teflon) can be found. Older insulation
materials included cotton, paper, or silk, but these are only useful for low-
temperature applications (up to 105°C).
For ease of manufacturing, most new magnet wire has insulation that acts
as a flux (metallurgy) when burnt during soldering. [1]
This means that the
electrical connections at the ends can be made without stripping off
the insulation first. Older magnet wire is normally not like this, and requires
sandpapering or scraping to remove the insulation before soldering.

43
Why must use an insulated copper wire for coils of an electromagnet? A
single coil of wire produces an electromagnetic field. Multiple coils add their
electromagnetic fields together for a stronger field. Using uninsulated copper wire
in the coils would resemble a single large coil because current would not flow
evenly through all the copper wires. Also, without insulation the resistance to the
flow of electricity would be reduced to near zero drawing too much current and
perhaps blowing a fuse or tripping a circuit breaker. E = IR and I = E/R, I
(current) is equal to E (voltage)/R(resistance) and I is large if R is small for a
given voltage.
A magnetic core is a piece of magnetic material with a
high permeability used to confine and guide magnetic fields in
electrical, electromechanical and magnetic devices such as
electromagnets, transformers, electric motors, generators, inductors,
magnetic recording heads, and magnetic assemblies. It is made
of ferromagnetic metal such as iron, or ferrimagnetic compounds such as ferrites.
The high permeability, relative to the surrounding air, causes the magnetic field
lines to be concentrated in the core material. The magnetic field is often created
by a coil of wire around the core that carries a current. The presence of the core
can increase the magnetic field of a coil by a factor of several thousand over what
it would be without the core.
The use of a magnetic core can enormously concentrate the strength and
increase the effect of magnetic fields produced by electric currents and permanent
magnets. The properties of a device will depend crucially on the following factors:
1. The geometry of the magnetic core.
2. The amount of air gap in the magnetic circuit.
3. The properties of the core material
(especially permeability and hysteresis).
4. The operating temperature of the core.
5. Whether the core is laminated to reduce eddy currents.
In many applications it is undesirable for the core to retain magnetization
when the applied field is removed. This property, called hysteresis can cause

44
energy losses in applications such as transformers. Therefore 'soft' magnetic
materials with low hysteresis, such as silicon steel, rather than the 'hard' magnetic
materials used for permanent magnets, are usually used in cores.
Commonly used core structures are:
Air core: A coil not containing a magnetic core is called an air core coil. This
includes coils wound on a plastic or ceramic form in addition to those made of
stiff wire that are self-supporting and have air inside them. Air core coils generally
have a much lower inductance than similarly sized ferromagnetic core coils, but
are used in radio frequency circuits to prevent energy losses called core losses that
occur in magnetic cores. The absence of normal core losses permits a higher Q
factor, so air core coils are used in high frequency resonant circuits, such as up to
a few megahertz. However, losses such as proximity effect and dielectric
losses are still present.
Straight cylindrical core: Most commonly made of ferrite or a similar material,
and used in radios especially for tuning an inductor. The rod sits in the middle of
the coil, and small adjustments of the rod's position will fine tune the inductance.
Often the rod is threaded to allow adjustment with a screwdriver. In radio circuits,
a blob of wax or resin is used once the inductor has been tuned to prevent the core
from moving.
The presence of the high permeability core increases the inductance but
the field must still spread into the air at the ends of the rod. The path through the
air ensures that the inductor remains linear. In this type of
inductor radiation occurs at the end of the rod and electromagnetic
interference may be a problem in some circumstances.
Single "I" core: Like a cylindrical rod but square, rarely used on its own. This type
of core is most likely to be found in car ignition coils.
"C" or "U" core: U and C-shaped cores are used with I or another C or U core to
make a square closed core, the simplest closed core shape. Windings may be put
on one or both legs of the core.
"E" core: E-shaped core are more symmetric solutions to form a closed magnetic
system. Most of the time, the electric circuit is wound around the center leg,

45
whose section area is twice that of each individual outer leg. A core shape derived
from E shape is used in this model.
When the core is subjected to a changing magnetic field, as it is in devices that
use AC current such as transformers, inductors, and AC motors and alternators,
some of the power that would ideally be transferred through the device is lost in
the core, dissipated as heat and sometimes noise. This is due primarily to two
processes:
1. Hysteresis - When the magnetic field through the core changes,
the magnetization of the core material changes by expansion and
contraction of the tiny magnetic domains it is composed of, due to
movement of the domain walls. This process causes losses, because the
domain walls get "snagged" on defects in the crystal structure and then
"snap" past them, dissipating energy as heat. This is called hysteresis loss.
It can be seen in the graph of the B field versus the H field for the material,
which has the form of a closed loop. The amount of energy lost in the
material in one cycle of the applied field is proportional to the area inside
the hysteresis loop. Since the energy lost in each cycle is constant,
hysteresis power losses increase proportionally with frequency.
2. Eddy currents - If the core is electrically conductive, the changing
magnetic field induces circulating loops of current in it, called eddy
currents, due to electromagnetic induction. The loops flow perpendicular
to the magnetic field axis. The energy of the currents is dissipated as heat
in the resistance of the core material. The power loss is proportional to the
area of the loops and inversely proportional to the resistivity of the core
material. Eddy current losses can be reduced by making the core out of
thin laminations which have an insulating coating, or alternately, making
the core of a nonconductive magnetic material, like ferrite.

46
Having no magnetically active core material (an "air core") provides very low
inductance in most situations, so a wide range of high-permeability materials are
used to concentrate the field. Most high-permeability material
are ferromagnetic or ferrimagnetic. The most common core materials are follows:
Soft iron:"Soft" (annealed) iron is used in magnetic assemblies, electromagnets
and in some electric motors; and it can create a concentrated field that is as much
as 50,000 times more intense than an air core. Iron is desirable to make magnetic
cores, as it can withstand high levels of magnetic field without saturating (up to
2.16 tesla at ambient temperature)
It is also used because, unlike "hard" iron, it does not remain magnetized
when the field is removed, which is often important in applications where the
magnetic field is required to be repeatedly switched. Unfortunately, due to the
electrical conductivity of the metal, at AC frequencies a bulk block or rod of soft
iron can often suffer from large eddy currents circulating within it that waste
energy and cause undesirable heating of the iron.
Laminated silicon steel: Because iron is a relatively good conductor, it cannot be
used in bulk form with a rapidly changing field, such as in a transformer, as
intense eddy currents would appear due to the magnetic field, resulting in huge
losses (this is used in induction heating).
Two techniques are commonly used together to increase the resistivity of iron:
lamination and alloying of the iron with silicon.
Lamination:
Fig No 4.8 Typical EI Lamination

47
Laminated magnetic cores are made of thin, insulated iron sheets, lying, as much
as possible, parallel with the lines of flux. Using this technique, the magnetic core
is equivalent to many individual magnetic circuits, each one receiving only a
small fraction of the magnetic flux (because their section is a fraction of the whole
core section). Because eddy currents flow around lines of flux, the laminations
prevent most of the eddy currents from flowing at all, restricting any flow to much
smaller and thinner and thus higher resistance regions. From this, it can be seen
that the thinner the laminations, the lower the eddy currents. This type of plates
are used here to make the core materials.
Silicon alloying: A small addition of silicon to iron (around 3%) results in a
dramatic increase of the resistivity, up to four times higher. Further increase in
silicon concentration impairs the steel's mechanical properties, causing difficulties
for rolling due to brittleness.
Among the two types of silicon steel, grain-oriented (GO) and grain non-
oriented (GNO), GO is most desirable for magnetic cores. It is anisotropic,
offering better magnetic properties than GNO in one direction. As the magnetic
field in inductor and transformer cores is static (compared to that in electric
motors), it is possible to use GO steel in the preferred orientation.
Carbonyl iron: Powdered cores made of carbonyl iron, a highly pure iron, have
high stability of parameters across a wide range of temperatures and magnetic
flux levels, with excellent Q factors between 50 kHz and 200 MHz. Carbonyl iron
powders are basically constituted of micrometer-size spheres of iron coated in a
thin layer of electrical insulation. This is equivalent to a microscopic laminated
magnetic circuit (see silicon steel, above), hence reducing the eddy currents,
particularly at very high frequencies.
A popular application of carbonyl iron-based magnetic cores is in high-
frequency and broadband inductors and transformers.
Iron powder: Powdered cores made of hydrogen reduced iron have higher
permeability but lower Q. They are used mostly for electromagnetic

48
interference filters and low-frequency chokes, mainly in switched-mode power
supplies.
Ferrite: Ferrite ceramics are used for high-frequency applications. The ferrite
materials can be engineered with a wide range of parameters. As ceramics, they
are essentially insulators, which prevents eddy currents, although losses such as
hysteresis losses can still occur.
Vitreous Metal: Amorphous metal is a variety of alloys that are non-crystalline or
glassy. These are being used to create high efficiency transformers. The materials
can be highly responsive to magnetic fields for low hysteresis losses and they can
also have lower conductivity to reduce eddy current losses. China is currently
making wide spread industrial and power grid usage of these transformers for new
installations.
Soft iron has a far greater magnetic permeability than steel. Meaning it
provides a stronger magnetic field for a given magnetization current (up to
saturation).
It has a much lower retentivity than steel - when the current is switched off the
remaining field strength is very weak (objects held by iron will be released , but
probably held by the significant 'permanent' field retained by steel). That’s why
soft iron core is used for core material.
During the last few years, considerable developments have place in the
field of magnetic materials. Presently magnetic materials having very high
permeability’s and low specific iron losses are available. These materials are
much superior and result into a reduced size of the machine with a lower overall
cost. As such they are replacing the poor magnetic materials previously used in
electrical machines. The most suitable magnetic materials for electrical machines,
which give a considerable reduction in size and cost, are silicon steel of various
grades.

49
Fig No 4.9 Electromagnet
The force exerted by an electromagnet on a section of core material is:
F= (B²A)/ (2μₒ)
The magnetic field created by an electromagnet is proportional to both the
number of turns in the winding, N, and the current in the wire, I, hence this
product, NI, in ampere-turns, is given the name magneto motive force. For an
electromagnet with a single magnetic circuit, of which length Lcore of the magnetic
field path is in the core material and length Lgap is in air gaps, Ampere's Law
reduces to:
Where
is the permeability of free space (or air)
For a closed magnetic circuit (no air gap), such as would be found in an
electromagnet lifting a piece of iron bridged across its poles, equation becomes:
B= (NIμ)/L

50
F= (μ²N²I²A)/(2μₒL²)
The above methods are inapplicable when most of the magnetic field path
is outside the core. For electromagnets (or permanent magnets) with well defined
'poles' where the field lines emerge from the core, the force between two
electromagnets can be found using the 'Gilbert model' which assumes the
magnetic field is produced by fictitious 'magnetic charges' on the surface of the
poles, with pole strength m and units of Ampere-turn meter. Magnetic pole
strength of electromagnets can be found from:
The force between two poles is:
The variables of the electromagnet are:
Permeability,μ =1.2567×10^-6 H/m
Number of turns,N =250
Current,I =7amp
Radius of core ,R =3cm
Area of cross section, A =Πd²/4
= 7.06×10^-4 m²
Permeability of free space,μₒ = 4Π×10^-7 N/A²
Length of core,L = 6cm

51
Calculating the attractive or repulsive force between two magnets is, in the
general case, an extremely complex operation, as it depends on the shape,
magnetization, orientation and separation of the magnets. The Gilbert model does
depend on some knowledge of how the 'magnetic charge' is distributed over the
magnetic poles. It is only truly useful for simple configurations even then.
Fortunately, this restriction covers many useful cases.
For two cylindrical magnets with radius , and height , with their
magnetic dipole aligned and the distance between them greater than a certain
limit, the force can be well approximated (even at distances of the order of ) by,
Where is the magnetization of the magnets and is the distance
between them. For small values of , the results are erroneous as the force
becomes large for close-to-zero distance.

52
CHAPTER 5
RESULTS AND DISCUSSIONS
Electromagnet is made by winding the insulated copper coil around the soft iron
piece. To end of the coil is leads to connections. The permanent magnet is
attached at the centre of piston head, with adhesives. According to the outside
pole of the permanent magnet electromagnet is connected to the battery, such that
the poles are identical and repel each other when comes closer. After that cylinder
and piston are arranged. Then the spring is aligned on the piston rod with end
covers. And fixed on the frame.
Fig. No 5.1 Shock absorber attached on frame

53
Since we have no exact equation to find the repulsive force between two
non identical magnet, its assumed that both magnets have shape, size, magnetic
force approximately same. For two cylindrical magnets with radius , and
height , with their magnetic dipole aligned and the distance between them
greater than a certain limit, the force can be well approximated (even at distances
of the order of ) by,
Fig No. 5.2 Repulsion of magnets
5.1 ELECTROMAGNETIC FORCE
The magnetic force generated by the electromagnet is calculated by formula
F= (μ²N²I²A)/(2μₒL²)
Permeability,μ =1.2567×10^-6 H/m
Number of turns, N =250
Current, I =7amp
Diameter of core ,d =3cm
Area of cross section, A =Πd²/4
= 7.06×10^-4 m²

54
Length of core, L = 6cm
Force, F = 300.48N
5.2 REPULSIVE FORCE BETWEEN MAGNETS
Radius of electromagnet, R = 3cm
Height of magnet, H =6cm
At normal condition the permanent magnet rest at distance of 10cm from
the core, and the minimum distance when it comes during shock is 3cm. So there
is a maximum and a minimum force, between these repulsion forces varies. As the
distance between magnets decreases the force will increase. But when it comes
closer the magnet will attract. So in order to avoid such situation a rubber bush is
placed over the electromagnet.
Magnetisation, M =Nm/V, m-unit vector in that direction
=(250/54)*m
= 4.62 A/m
Therefore Repulsive force,
When x =x1
i.e., x =3cm, Repulsive force will be maximum
Fmax = 4.23×10^-6 N
When x =x2
i.e., x =10 cm, Repulsive force will be minimum
Fmin = 3.748×10^-7 N

55
5.3 CRITICAL DAMPING COEFFICIENT
Stiffness of spring, K = 41720 N/m
Mass of spring, m = 0.650kg
Linear resonance frequency, fres =127Hz
Angular natural frequency, ωn = 797.96 rad/s
Critical damping coefficient, Cc =2 ( )
= 2 ( )
=329.35
5.4 DESIGN OF SHOCK ABSORBER
Fig No 5.3 Piston and cylinder view

56
Fig No 5.4 Damper

57
5.5 BILLING
No ITEM No. of ITEMS COST
₹
1
Cylinder & Piston 1 650
2
Coil Spring 1 250
3
Neodymium Magnet 1 350
4
Copper Coil 10mtrs 100
5
Insulated plate 15 30
6
Wire 3mtrs 20
7
Machining cost
100
Total, ₹ 1500
Table 5.1 Billing table

58
CHAPTER 6
SCOPE AND FUTURE OF PROJECT
The riding comfort ability is one of the main factors that considered in designing.
Shock absorbers, linear dampers, and dashpots are devices designed to provide
absorption of shock and smooth deceleration in linear motion applications. The
road conditions are different at places. An automobile is designed to perform best
at all places. Suspension system will help to maintain better stability at any state.
Hydraulic and gas charged shock absorbers are commonly used now a days. But at
severe shock load the hydraulic shock absorbers may fail. The fluids get leaked.
So in introducing magnets in the shock absorber to provide damping effect is an
efficient method.
During the shock loads the damper will absorbs the energy, in case of the
fluidic type it take time. These create an unstable condition. And the passengers
want to suffer its after effects. In case of racing cars, the loads are suddenly
fluctuating type and the vibrations wants to remove as soon as possible. General
principle similar poles deflect; can be applied to absorb the damping effect by
providing the magnets. And there is no contact between parts inside the damper,
so the friction is negligible.
The absence of conductive medium will also help to remove hysteresis
effect. The design can be varied to the required conditions and the component
such as electromagnets are available on the requirement. While considering the
additional cost for fabrication it’s not large when compared with the performance.
The levitation based researches are presently takes place. So more improved
magnetic parts will be available easily in future.
Actually now it’s a conceptual model. We are not included the features
such as sensor to detect the deflection of the coil spring. Depending on the
deflection magnetic field with required strength can be induced, that will help to
make the repulsive force to dampen the shock loads in few seconds. During this
project we had studied various method of suspension system, using the magnetic
properties.

59
We had noticed that when any two leads of the three phase induction
motor were shorted then we had to apply more force to rotate the shaft. If it is
coupled with the suspension system like a torque arm suspension system, we can
damper the force without any expenditure of energy. The only requirement will be
the shorting circuit. We hope these high performance suspension systems will
incorporate in coming generation vehicles, which will remove the defects caused
by the current models.

60
REFERENCES
1. Andrzej Milecki , Miko Aj Hauke,2012, Application Of
Magnetorheological ﬂuid In Industrial Shock Absorbers, Mechanical
Systems And Signal Processing 28,528–541
2. Babak Ebrahimi , Mir Behrad Khamesee , M. Farid Golnaraghi,2008,
Design And Modeling Of A Magnetic Shock Absorber Based On Eddy
Current Damping Effect, Journal Of Sound And Vibration 315, 875–889.
3. Alberdi-Muniain , N. Gil-Negrete , L. Kari, 2012,Direct Energy ﬂow
Measurement In Magneto-Sensitive Vibration Isolator Systems, Journal Of
Sound And Vibration 331,1994–2006
4. Bart.L.J.Gysen, Johannes.J.H.Paulides, Jeroen.L.G.Janssen, 2010, Active
Electromagnetic Suspension System For Improved Vehicle Dynamics,
IEEE Transactions On Vehicular Technology, Vol.59.No.3
5. Georgios Tsampardoukas, Charles W.Stammers, Emanuele Guglielmino,
2008,Hybrid Balance Control Of A Magnetorheological Truck
Suspension, Journal Of Sound And Vibration31.7 ,514-536
6. Kirk T. Mcdonald, Joseph Henry Laboratories, Princeton University,
Princeton, NJ08544,2012, Magnetic Damping
7. Zekeriya Parlak, Tahsin Engin, Ismail Çallı, 2012,Optimal Design Of MR
Damper Via Finite Element Analyses Of Fluid Dynamic And Magnetic
Field, Mechatronics 22, 890–903
8. Lei Zuo, Xiaoming Chen, Samir Nayfeh, 2011,Design And Analysis Of A
New Type Of Electromagnetic Damper With Increased Energy Density,
Journal Of Vibration And Acoustics, Vol.133/041006-1
9. R. Zalewski , J. Nachman , M. Shillor , J. Bajkowski,2013, Dynamic
Model For A Magnetorheological Damper, Applied Mathematical
Modelling
10. Pinjarla.Poornamohan, Lakshmana Kishore.T,2012, Design And Analysis
Of A Shock Absorber,IJRET,Vol 1,Issue 4, 578-592

61
11. Michael James Atherden,2004, Formula Sae Shock Absorber Design, The
University Of Queensland, BE thesis, 51-54
12. Bogdan Sapinski,2009, Magnetorheological Damper in Vibrational
Control of Mechanical Structures, Mechanics,Vol 1, No 1,18-25

Electromagnetic Shock Absorber

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