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MAHATMA GANDHI INSTITUTE OF TECHNOLOGY

(Affiliated to JNTUH,Hyderabad)

Accredited by NBA, New Delhi

Gandipet, Hyderabad- 5000075

www.mgit.ac.in

2016

DEPARTMENT OF MECHANICAL ENGINEERING

CERTIFICATE

This is to certify that this project report entitled “Electromagnetic suspension

system” has been submitted by B.SUMANTH (12261A0312), K.PRAVEEN

KUMAR (12261A0333), M.P.DANIEL MARK (12261A0336) in partial fulfilment

of the requirements for the award of the degree of BACHELOR OF

TECHNOLOGY in MECHANICAL ENGINEERING under Jawaharlal Nehru

Technological University, Hyderabad, during the academic year 2015-16, is a bonafide

record of work carried out under my guidance and supervision.

The results embodied in this report have not been submitted to any other University or

Institution for the award of any degree or diploma.

Mr.V.V.N.Satya Suresh Prof.Dr.K.Sudhakar Reddy

Associate Professor Head of the Department

Internal Guide

Internal Examiner External Examiner

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ACKNOWLEDGEMENT

At the outset, we express our deepest sense of gratitude to our guide Mr.V.V.N.Satya

Suresh mechanical Department, MGIT, Hyderabad, for giving us an opportunity to

work on a project that was so challenging and interesting for us. We remember with

great emotion, the constant encouragement and help extended to us by him that went

even beyond the realm of academics.

We express our profound gratitude to Prof.Dr.K.Sudhakar Reddy, Head of

Mechanical Engineering Department, MGIT, Hyderabad.

We are delighted to work under our principal of MGIT Dr.G.Chandra Mohan Reddy

and grateful to him for his inspiring and invigorating presence.

Our sincere thanks go to all the faculty members of the department and technicians for

the voluntary help, extended to us during the course of the project work.

B.Sumanth (12261A0312)

K.Praveen Kumar (12261A0333)

M.P.Danial Mark (12261A0336)

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ABSTRACT

Presently automobiles and machines use incompressible fluids as shock absorbers in

order to absorb sudden shocks and vibrations that arise under motion. These shock

absorbers provide damping effect thus converting Kinetic energy of sudden shock into

heat energy which is then dissipated.

Our attempt is to design electromagnets in order to replace these shock absorbers by

using the concept of polarity.

This system consists of two electromagnets and a 12V battery assembled in such a way

that a clearance is maintained between these two electromagnets by placing similar

poles on the same side. Whenever there is a sudden shock (or) a vibration, this clearance

between two electromagnetic plates provides damping effect.

This project resulted in increased comfort for passenger travelling in automobiles and

reduced annoying sounds in machines. It also minimized the damage to the floor carried

due to vibrations. Moreover the additional advantage using this concept is clearance can

be varied by making changes in the input voltage and the number of windings.

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LIST OF FIGURES

Figure.No Description Page.no

2.1 Suspension system........................................................................... 6

2.2 Types of suspension ........................................................................ 7

2.3 Twist beam ...................................................................................... 9

2.4 Passive suspension system ............................................................ 10

2.5 Inter connected suspension system ............................................... 12

2.6 Types of shock absorber................................................................ 15

3.1 Electromagnet................................................................................ 20

3.2 Electromagnet with a central shaft ................................................ 23

3.3 50mm dia solenoids with a through hole ...................................... 24

3.4 Repulsive electromagnets.............................................................. 25

3.5 Electromagnet with increased windings........................................ 26

3.6 Iron bar pushing away the winded non-conducting material ........ 28

3.7 Attraction for 20mm dia ................................................................ 29

3.8 Magnetic attraction........................................................................ 30

3.9 Magneticrepulsion ......................................................................... 30

3.10 Electromagnets .............................................................................. 31

4.1 Block diagram of the prototype ................................................. 32

4.2 M.S Stand .................................................................................... 33

4.3 Winding wire (Gauge 28) ............................................................ 33

4.4 12v 7.5 amps lead acid battery ..................................................... 36

5.1 Series and Parallel Circuits ........................................................... 48

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LIST OF TABLES

Table.No Description Page.no

Table 1 Battery specifications .................................................................... 36

Table 2 Results of different trials made ...................................................... 42

Table 3 Graph of Dia of the Rod v/s magnetic field strength ..................... 44

Table 4 Graph of Length of Solenoid v/s magnetic strength ...................... 45

Table 5 Graph of Voltage v/s Magnetic strength in kgf.............................. 46

Table 6 Graph on Current v/s Magnetic strength in Kgf............................. 47

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1

CONTENTS

CERTIFICATE ----------------------------------------------------------------------------------------- i

ACKNOWLEDGEMENT -------------------------------------------------------------------------- ii

ABSTRACT ---------------------------------------------------------------------------------------------iii

LIST OF FIGURES -----------------------------------------------------------------------------------iv

LIST OF TABLES ------------------------------------------------------------------------------------ v

1 INTRODUCTION ------------------------------------------------------------------------------- 4

1.1 Project synopsis ----------------------------------------------------------------- 4

1.2 Objectives ----------------------------------------------------------------------- 4

1.3 Overview ------------------------------------------------------------------------ 5

2 THEORETICAL BACKGROUND OF THE SUSPENSION SYSTEM --------- 6

2.1 Suspension system -------------------------------------------------------------- 6

2.1.1 Types of Suspension System ----------------------------------------------- 7

2.1.2 Dampers -------------------------------------------------------------------- 9

2.2 Shock absorber ---------------------------------------------------------------- 12

2.3 Types of vehicle shock absorbers --------------------------------------------- 12

2.3.1 Twin- tube----------------------------------------------------------------- 13

2.3.2 Mono-tube ---------------------------------------------------------------- 15

2.4 Comparison of Two Shock Absorbers ---------------------------------------- 16

2.4.1 Twin-Tube Shock Absorber ---------------------------------------------- 16

2.4.2 Single-Tube Shock Absorber--------------------------------------------- 16

2.5 Theoretical approaches -------------------------------------------------------- 17

2.6 Investigation on electromagnetic suspension --------------------------------- 19

3 METHODOLOGY ----------------------------------------------------------------------------- 20

3.1 Electromagnets ---------------------------------------------------------------- 20

3.2 Design of power full electromagnets------------------------------------------ 24

2

3.3 Attempts and Description ----------------------------------------------------- 24

3.3.1 CASE 1 ----------------------------------------------------------------------- 24

3.3.2 CASE 2 ----------------------------------------------------------------------- 25

3.3.3 CASE 3 ----------------------------------------------------------------------- 26

3.3.4 CASE 4 ----------------------------------------------------------------------- 26

3.3.5 CASE 5 ----------------------------------------------------------------------- 27

3.3.6 CASE 6 ----------------------------------------------------------------------- 28

3.3.7 CASE 7 ----------------------------------------------------------------------- 29

3.3.8 CASE 8 ----------------------------------------------------------------------- 31

4 FABRICATION OF SUSPENSION SYSTEM ----------------------------------------- 32

4.1 Components used in design --------------------------------------------------- 32

4.1.1 Supporting stand structure------------------------------------------------ 32

4.1.2 Copper wire -------------------------------------------------------------- 33

4.1.3 Battery -------------------------------------------------------------------- 35

4.1.4 Electromagnets ----------------------------------------------------------- 36

4.1.5 Switches ------------------------------------------------------------------ 39

4.2 Design and Assembly --------------------------------------------------------- 40

4.3 Analysis of the material used in the design ----------------------------------- 41

4.3.1 Mild steel ----------------------------------------------------------------- 41

4.3.2 Aluminum ---------------------------------------------------------------- 41

5 RESULTS AND DISCUSSION ------------------------------------------------------------- 42

5.1 Variation of magnetic field with respect to number of windings ------------- 43

5.2 Variation of magnetic strength with respect to diameter---------------------- 44

5.3 Variation of magnetic strength with respect to length of the solenoid -------- 45

5.4 Variation of magnetic strength with respect to voltage ----------------------- 46

5.5 Variation of magnetic strength with respect to current ----------------------- 47

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5.6 Series and parallel circuits ---------------------------------------------------- 48

5.6.1 Series connection --------------------------------------------------------- 48

5.6.2 Parallel connection ------------------------------------------------------- 48

6 ADVANTAGES --------------------------------------------------------------------------------- 49

7 CONCLUSION ---------------------------------------------------------------------------------- 50

7.1 Design ------------------------------------------------------------------------- 50

7.2 Safety -------------------------------------------------------------------------- 50

7.3 Ride Comfort ------------------------------------------------------------------ 50

7.4 Fail Safe ----------------------------------------------------------------------- 50

7.5 Overview ---------------------------------------------------------------------- 50

8 BIBLIOGRAPHY ------------------------------------------------------------------------------ 51

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1 INTRODUCTION

The sole purpose of this project is to improvise the existing suspension system by

replacing the present shock absorbers with electromagnets.

The present shock absorbers consist of incompressible fluid which converts the kinetic

energy in to heat energy and dissipated. As all the parts are in contact with each other

even though it is damping sudden shocks, due to direct contact these vibrations are

transferred. Some of the disadvantages of the present shock absorbers are:

1) Damage of the vehicle components due to vibrations.

2) Failure of parts due to sudden shocks.

3) Discomfort for passengers due to vibrations.

4) Floor damage in case of machines due to vibrations.

If we analyze the drawbacks of the present shock absorbers, all the above problems can

be solved by simply eliminating the contact between the wheels and chassis of the

vehicle.

Therefore as a student of mechanical engineering this project will expose me to the field

of designing and allows me to study the detailed properties of electromagnets.

1.1 Project synopsis

In this project in order to raise the upper part of the body from the lower one,

electromagnets are used. These electro magnets are placed in such a way that similar

poles are placed on the same side so that the repel each other and as the moment in

horizontal direction is constrained it starts moving up lifting up the body of the vehicle.

1.2 Objectives

First and foremost design of mechanical part of an electromagnet is an important aspect

in this project, which would be close to practical applications. Design should be flexible

and more efficient in absorption of the vibrations.

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Developing the powerful electromagnets according to the requirement of magnetic force

which is used to damp maximum amount of vibrations is to be done in this project. To

get highest value of the magnetic strength a number of case studies to be conducted by

varying length, diameter, windings of solenoid and also changing the voltage and

current which passes through the windings.

Finally structure will be designed which should support the complete system. Structure

should be more flexible so as to withstand the weight of system and external loads.

1.3 Overview

Theoretical background of suspension system is given in detail so as to make aware of

present generation suspension system, and the components of the suspension system.

Methodology includes various case studies we made; they also include different

attempts we made to increase the magnetic strength of the electromagnets.

Fabrication of suspension system is the place where the design of the prototype is made.

A prototype is a simple replica of the shock absorber that we made using the concept of

electromagnets.

Results and discussions include various results that we got during several case studies.

Graphs were plotted based on those results.

Advantages and disadvantages are the next topic of the report. It explains how our

project overcomes the drawbacks of the present shock absorbers.

Conclusion is made by giving an overview on the project followed by a discussion on

future scope of the project.

Bibliography is made in order to tell, what were the journals and books that we referred

before jumping into conclusions.

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2 THEORETICAL BACKGROUND OF THE

SUSPENSION SYSTEM

2.1 Suspension system

Suspension is the system of tires, tire air, springs, shock absorbers and linkages that

connects a vehicle to its wheels and allows relative motion between the two. Suspension

systems serve a dual purpose contributing to the vehicle's road holding/handling and

braking for good active safety and driving pleasure, and keeping vehicle occupants

comfortable and a ride quality reasonably well isolated from road noise, bumps,

vibrations, etc.

2.1suspension system. courtesy (Wikipedia)

These goals are generally at odds, so the tuning of suspensions involves finding the

right compromise. It is important for the suspension to keep the road wheel in contact

with the road surface as much as possible, because all the road or ground forces act ing

on the vehicle do so through the contact patches of the tires. The suspension also

protects the vehicle itself and any cargo or luggage from damage and wear. The design

of front and rear suspension of a car may be different.

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2.1.1 Types of Suspension System

Suspension systems can be broadly classified into two subgroups

1) Dependent system

2) Independent system

2.1.1.1 Dependent system

A dependent suspension normally has a beam (a simple 'cart' axle) or (driven) live

axle that holds wheels parallel to each other and perpendicular to the axle. When the

camber of one wheel changes, the camber of the opposite wheel changes in the same

way (by convention on one side this is a positive change in camber and on the other side

this a negative change).

In a front engine, rear-drive vehicle, dependent rear suspension is either "live axle"

or deDion axle, depending on whether or not the differential is carried on the axle.

Because it assures constant camber, dependent (and semi- independent) suspension is

most common on vehicles that need to carry large loads as a proportion of the vehicle

weight, that have relatively soft springs and that do not (for cost and simplicity reasons)

use active suspensions. The use of dependent front suspension has become limited to

heavier commercial vehicles.

2.2 Types of suspension. courtesy (Wikipedia)

2.1.1.2 Independent system

An independent suspension allows wheels to rise and fall on their own without affecting

the opposite wheel. Suspensions with other devices, such as sway bars that link the

wheels in some way are still classed as independent.

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Transverse leaf springs when used as a suspension link or four quarter elliptic on one

end of a car are similar to wishbones in geometry, but are more compliant. Examples

are the front of the original Fiat 500 and the early examples of Peugeot 403 and the back

of the AC Ace.

Because the wheels are not constrained to remain perpendicular to a flat road surface in

turning, braking and varying load conditions, control of the wheel camber is an

important issue. Swinging arm was common in small cars that were sprung softly and

could carry large loads, because the camber is independent of load. Some active and

semi-active suspensions maintain the ride height, and therefore the camber, independent

of load. In sports cars, optimal camber change when turning is more important.

Wishbone and multi- link allow the engineer more control over the geometry, to arrive at

the best compromise, than swing axle, MacPherson strut or swinging arm do; however

the cost and space requirements may be greater. Semi-trailing arm is in between, being a

variable compromise between the geometries of swinging arm and swing axle.

2.1.1.3 Semi independent

A third type is a semi-dependent suspension. In this case, the motion of one wheel does

affect the position of the other but they are not rigidly attached to each other. A twist-

beam rear suspension is such a system.

In semi- independent suspensions, the wheels of an axle are able to move relative to one

another as in an independent suspension but the position of one wheel has an effect on

the position and attitude of the other wheel. This effect is achieved via the twisting or

deflecting of suspension parts under load. The most common type of semi- independent

suspension is the twist beam.

The twist-beam rear suspension (also torsion-beam axle or deformable torsion

beam) is a type of automobile suspension based on a large H or C shaped member. The

front of the H attaches to the body via rubber bushings, and the rear of the H carries

each stub-axle assembly, on each side of the car. The cross beam of the H holds the two

trailing arms together, and provides the roll stiffness of the suspension, by twisting as

the two trailing arms move vertically, relative to each other.

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2.3 Twist beam. courtesy (Wikipedia)

2.1.2 Dampers

Most conventional suspensions use passive springs to absorb impacts and dampers

(or shock absorbers) to control spring motions.

We have three types of suspensions

1) Passive

2) Semi-active and Active

3) Inter connected

2.1.2.1 Passive suspension

Traditional springs and dampers are referred to as passive suspensions most vehicles are

suspended in this manner.

2.1.2.1.1 Springs

The majority of land vehicles are suspended by steel springs, of these types: Leafspring,

Torsion beam, suspensionCoil spring.

2.1.2.1.2 Dampers or shock absorbers

The shock absorbers damp out the (otherwise simple harmonic) motions of a vehicle up

and down on its springs. They also must damp out much of the wheel bounce when the

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unsprung weight of a wheel, hub, axle and sometimes brakes and differential bounces

up and down on the springiness of a tire. Some have suggested that the regular bumps

found on dirt are caused by this wheel bounce, though some evidence exists that it is

unrelated to suspension at all.

2.4 Passive suspension system. courtesy (Wikipedia)

2.1.2.2 Semi-active and active suspensions

Semi-active suspensions include devices such as air springs and switchable shock

absorbers, various self- levelling solutions, as well as systems like

pneumatic, hydrolastic and hydragas suspensions.

Mitsubishi developed the world’s first production semi-active electronically controlled

suspension system in passenger cars; the system was first incorporated in the

1987 Galant model. Delphi currently sells shock absorbers filled with a magneto-

rheological fluid, whose viscosity can be changed electromagnetically, thereby giving

variable control without switching valves, which is faster and thus more effective.

Fully active suspension systems use electronic monitoring of vehicle conditions,

coupled with the means to impact vehicle suspension and behaviour in real time to

directly control the motion of the car. Lotus Cars developed several prototypes, from

1982 onwards, and introduced them to F1, where they have been fairly effective, but

have now been banned. Nissan introduced a low bandwidth active suspension in circa

1990 as an option that added an extra 20% to the price of luxury models. Citroën has

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also developed several active suspension models (see hydractive). A recently publicized

fully active system from Bose Corporation uses linear electric motors (i.e., solenoids) in

place of hydraulic or pneumatic actuators that have generally been used up until

recently. Mercedes introduced an active suspension system called Active Body Control

in its top-of-the-line Mercedes-Benz CL-Class in 1999.

Several electromagnetic suspensions have also been developed for vehicles. Examples

include the electromagnetic suspension of Bose, and the electromagnetic suspension

developed by prof.Laurentiu Encica. In addition, the new Michelin wheel with

embedded suspension working on an electromotor is also similar.

1.5 Interconnected suspension. courtesy (Wikipedia)

Interconnected suspension, unlike semi-active/active suspensions, could easily decouple

different vehicle vibration modes in a passive manner. The interconnections can be

realized by various means, such as mechanical, hydraulic and pneumatic. Anti-roll bars

are one of the typical examples of mechanical interconnections, while it has been stated

that fluidic interconnections offer greater potential and flexibility in improving both the

stiffness and damping properties.

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2.5 Inter connected suspension system. courtesy (Wikipedia)

2.2 Shock absorber

A shock absorber (in reality, a shock "damper") is a mechanical or hydraulic device

designed to absorb and damp shock impulses. It does this by converting the kinetic

energy of the shock into another form of energy (typically heat) which is then

dissipated. A shock absorber is a type of dashpot.

Pneumatic and hydraulic shock absorbers are used in conjunction with cushions and

springs. An automobile shock absorber contains spring- loaded check valves and orifices

to control the flow of oil through an internal piston.

One design consideration, when designing or choosing a shock absorber, is where that

energy will go. In most shock absorbers, energy is converted to heat inside the viscous

fluid. In hydraulic cylinders, the hydraulic fluid heats up, while in air cylinders, the hot

air is usually exhausted to the atmosphere. In other types of shock absorbers, such as

electromagnetic types, the dissipated energy can be stored and used later. In general

terms, shock absorbers help cushion vehicles on uneven roads.

2.3 Types of vehicle shock absorbers

Most vehicular shock absorbers are either twin-tube or mono-tube types with some

variations on these themes.

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2.3.1 Twin-tube

2.3.1.1 Basic twin-tube

Also known as a "two-tube" shock absorber, this device consists of two nested

cylindrical tubes, an inner tube that is called the "working tube" or the "pressure tube",

and an outer tube called the "reserve tube". At the bottom of the device on the inside is a

compression valve or base valve. When the piston is forced up or down by bumps in the

road, hydraulic fluid moves between different chambers via small holes or "orifices" in

the piston and via the valve, converting the "shock" energy into heat which must then be

dissipated.

2.3.1.2 Twin-tube gas charged

Variously known as a "gas cell two-tube" or similarly-named design, this variation

represented a significant advancement over the basic twin- tube form. Its overall

structure is very similar to the twin- tube, but a low-pressure charge of nitrogen gas is

added to the reserve tube. The result of this alteration is a dramatic reduction in

"foaming" or "aeration", the undesirable outcome of a twin- tube overheating and failing

which presents as foaming hydraulic fluid dripping out of the assembly. Twin-tube gas

charged shock absorbers represent the vast majority of original modern vehicle

suspensions installations.

2.3.1.3 Position sensitive damping

Often abbreviated simply as "PSD", this design is another evolution of the twin-tube

shock. In a PSD shock absorber, which still consists of two nested tubes and still

contains nitrogen gas, a set of grooves has been added to the pressure tube. These

grooves allow the piston to move relatively freely in the middle range of travel (i.e., the

most common street or highway use, called by engineers the "comfort zone") and to

move with significantly less freedom in response to shifts to more irregular surfaces

when upward and downward movement of the piston starts to occur with greater

intensity (i.e., on bumpy sections of roads— the stiffening gives the driver greater

control of movement over the vehicle so its range on either side of the comfort zone is

called the "control zone"). This advance allowed car designers to make a shock absorber

tailored to specific makes and models of vehicles and to take into account a given

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vehicle's size and weight, its maneuverability, its horsepower, etc. in creating a

correspondingly effective shock.

2.3.1.4 Acceleration sensitive damping

The next phase in shock absorber evolution was the development of a shock absorber

that could sense and respond to not just situational changes from "bumpy" to "smooth"

but to individual bumps in the road in a near instantaneous reaction. This was achieved

through a change in the design of the compression valve, and has been termed

"acceleration sensitive damping" or "ASD". Not only does this result in a complete

disappearance of the "comfort vs. control" tradeoff, it also reduced pitch during vehicle

braking and rolls during turns. However, ASD shocks are usually only available as

aftermarket changes to a vehicle and are only available from a limited number of

manufacturers.

2.3.1.5 Coil over

Coilover shock absorbers are usually a kind of twin- tube gas charged shock absorber

around which has been mounted a large metal coil. Though common on motorcycle and

scooter rear suspensions, coilover shocks are uncommon in original equipment designs

for vehicles, though they have become widely available as aftermarket add-ons.

Coilover shocks for cars have been considered specialty items for high performance and

racing applications where they allow for significant reductions in overall vehicle height,

and though high-quality aftermarket options with wide sturdy springs may provide

improvements in vehicle performance, there is dispute over whether or not most

aftermarket coilover shocks confer any material benefits to most drivers and may in fact

reduce performance over original equipment installations.

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2.6Types of shock absorber. courtesy (Wikipedia)

2.3.2 Mono-tube

The principal design alternative to the twin-tube form has been the mono-tube shock

absorber which was considered a revolutionary advancement when it appeared in the

1950s. As its name implies, the mono-tube shock, which is also a gas-pressurized shock

and also comes in a coilover format, consists of only one tube, the pressure tube, though

it has two pistons. These pistons are called the working piston and the dividing or

floating piston, and they move in relative synchrony inside the pressure tube in response

to changes in road smoothness. The two pistons also completely separate the shock's

fluid and gas components. The mono-tube shock absorber is consistently a much longer

overall design than the twin- tubes, making it difficult to mount in passenger cars

designed for twin-tube shocks. However, unlike the twin-tubes, the mono-tube shock

can be mounted either way— it does not have any directionality. It also does not have a

compression valve, whose role has been taken up by the dividing piston, and although it

contains nitrogen gas, the gas in a mono-tube shock is under high pressure (260-

360 p.s.i. or so) which can actually help it to support some of the vehicle's weight,

something which no other shock absorber is designed to do.

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2.4 Comparison of Two Shock Absorbers

2.4.1 Twin-Tube Shock Absorber

The advantages and disadvantages of the twin-tube shock absorber are:

Advantages:

• Allows ride engineers to move beyond simple velocity sensitive on the valves and to

use the position of the piston to fine tune the ride characteristic.

• Adjusts more rapidly to changing road and weight conditions than single-tube shock

absorbers.

• A control is enhanced without sacrificing driver comfort. Two shocks absorbers into

one comfort and control.

Disadvantages: • Can only be mounted in one direction.

Current Uses: • Original equipment on many domestic passenger cars, SUV and light

truck applications.

2.4.2 Single-Tube Shock Absorber

The advantages and disadvantages of the single-tube designs are:

Advantages: • Easy to tailor to specific applications, as the larger piston diameter

allows low working pressures.

• Sufficient room for valves and passages.

• Can be installed in any position, can be mounted upside down, reducing the unsprung

weight.

• May run cooler. Heat is dissipated directly via the outer tube because it is exposed to

the air.

Disadvantages: • Longer than twin-tube shock absorbers.

• The outer tube, which acts as a guide cylinder for the piston, is susceptible to damage

from stone throw, etc. A dent in the pressure tube will destroy the unit.

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• Suspension layout must provide sufficient room for the tube which, with its very close

tolerances, is not to be mechanically impeded in any way. This is a disadvantage when

lines must be routed around the shock absorber in restricted bodywork areas.

• The piston rod seal is subjected to the damping pressure.

• Difficult to apply to passenger cars designed OE with twin-tube designs.

Current Uses: • Original equipment for many import and domestic passenger cars,

SUV and light truck applications. • Available for many after market applications.

2.5 Theoretical approaches

There are several commonly used principles behind shock absorption:

Hysteresis of structural material for example the compression of rubber disks, stretching

of rubber bands and cords, bending of steel springs, or torsion 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 absorbers are damped,

to extent, by the hysteresis of their springs and frames.

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.

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.

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 Mors racing 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

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response to a bump) and 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.

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. Enclosed gas is

compressible, so equipment is less subject to shock damage. This concept was first

applied in series production on Citroën cars in 1954. Today, many shock absorbers are

pressurized with compressed nitrogen, to reduce the tendency for the oil

to activate 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. 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).

Inertial resistance to acceleration, for example prior to 1966 the Citroën 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.

Composite hydro pneumatic suspension combines many suspension elements in a single

device: spring action, shock absorption, ride-height control, and self levelling

suspension. This combines the advantages of gas compressibility and the ability

of hydraulic machinery to apply force multiplication.

Conventional shock absorbers can be combined with Air suspension springs - an

alternate way to achieve ride-height control, and self levelling suspension.

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.

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Magnetic field variation magneto rheological damper changes its fluid characteristics

through an electromagnet.

The effect of a shock absorber at high (sound) frequencies is usually limited by using a

compressible gas as the working fluid or mounting it with rubber bushings.

2.6 Investigation on electromagnetic suspension

Electromagnetic suspension (EMS) is the magnetic levitation of an object achieved by

constantly altering the strength of a magnetic field produced by electromagnets using

feedback loop. In most cases the levitation effect is mostly due to permanent magnets as

they don't have any power dissipation, with electromagnets only used to stabilize the

effect.

According to Earnshaw's Theorem a paramagnetically magnetized body cannot rest in

stable equilibrium when placed in any combination of gravitational and magneto static

fields. In these kinds of fields an unstable equilibrium condition exists. Although static

fields cannot give stability, EMS works by continually altering the current sent to

electromagnets to change the strength of the magnetic field and allows a stable

levitation to occur. In EMS a feedback loop which continuously adjusts one or more

electromagnets to correct the object's motion is used to cancel the instability.

Many systems use magnetic attraction pulling upwards against gravity for these kinds of

systems as this gives some inherent lateral stability, but some use a combination of

magnetic attraction and magnetic repulsion to push upwards.

Magnetic levitation technology is important because it reduces energy consumption,

largely obviating friction. It also avoids wear and has very low maintenance

requirements. The application of magnetic levitation is most commonly known for its

role in Maglev trains.

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3 METHODOLOGY

3.1 Electromagnets

When a conducting wire is wounded around a metal rod and current is allowed to pass

through them, magnetic flux is generated across the windings and this each winding acts

as a piece of magnet. These when aligned very closely they induce current into the rod,

thereby making the rod a magnet.

3.1 Electromagnet. courtesy (Wikipedia)

These electromagnets execute the similar properties as that of permanent magnets. Now

we know that similar poles of a magnet repel each other the same principle is used in

making the electromagnetic suspension system.

Theoretical approach of the project starts from the following formula:-

F=CAnI/L

Where,

C = Proportionality Constant (Generally ranges from 0.009 -0.010 psi)

A = Cross sectional area of the plunger

n = No. of turns around the solenoid

I = Current passing through the wire

L= Length of the solenoid

21

Sample calculation

Where

C=0.009

A=0.25

n=200

I=7.5

L=120

F= (0.009×3.14×0.25×200×7.5)/120

= 0.08 kgf

An electric current flowing in a wire creates a magnetic field around the wire, due

to Amperes 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 centre of the coil, creating a strong magnetic field

there. A coil forming the shape of a straight tube is called a solenoid

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.

From the above formula we can theoretically calculate the magnetic power of the

electromagnets. However coming to real life applications several losses will take place

such as Eddy current losses etc.

22

3.2 Increasing the magnetic power of an Electro magnet

In order to make an electromagnetic suspension system we need to connect the lower

magnet to the wheel and the upper magnet to the frame of the vehicle which levitates in

the air, such that whenever there is a sudden shock to the vehicles due to the unevenness

of the road this clearance between the two electromagnets will damp the sudden impulse

and provides more comfort.

These types of electromagnets readily absorb all the forced vibrations that arise due to

the moment of the vehicle.

The only way to attain the required situation is by increasing the magnetic power of the

electromagnets.

3.2.1 Ways to increase the electromagnetic power

By following below steps we can increase the magnetic strength of an electromagnet.

Increasing the number of windings

By increasing the number of windings, the number of magnet like acting particles

increases thereby more induction takes place and the magnetic strength increases.

Increasing the Voltage and current

By increasing the voltage and current more electricity passes through the windings so

that the atoms receive more energy and magnetic strength increases.

Increasing the surface Area

By increasing the surface area windings get more closely to the solenoid there by it

increases the magnetic strength.

Inscribing another conducting material through the core

When we inscribe a conducting material through the solenoid it increases the magne tic

strength rapidly around 10 times. It was shown in the following figure.

23

3.2 Electromagnet with a central shaft. courtesy (Wikipedia)

24

3.2 Design of power full electromagnets

In consideration with design of suspension system to meet practical applications, we

decided to start with 50mm dia of solenoid.

3.3 Attempts and Description

3.3.1 CASE 1

As we know the properties of the electromagnets a design is made in such a way that

two solenoids of 50mm diameter with a through hole is winded with a copper wire, so

that a supporting shaft is passed through this through hole and by considering the theory

of the magnetic property, the magnetic strength of the electromagnet should be

increased. The design explained above is shown below.

3.3 50mm dia solenoids with a through hole. courtesy (Prototype)

However the attempt is a failure because instead of getting polarity on both the surfaces

these electro magnets exerted polarity on the inner and outer surface of the solenoid.

Reason for failure

The reason for failure of this attempt is that the polarity of a magnet keeps on changing

at their edges and as we made a through hole inside the solenoid it acted as an edge and

it got a chance to change its polarity.

So even though we followed the theoretical formula it didn’t gave the expected results.

25

3.3.2 CASE 2

In order to overcome the previous problem the through hole is eliminated and flat

solenoids were replaced in the place of them. For this the whole design is changed such

that instead of placing a supporting shaft through the hole a frame is made outside the

electro magnets as shown in the following figure such that these electromagnets will

slide inside the supporting frame and as the surface area is increased and the corners and

edges were eliminated. By doing so an increased magnetic strength is expected.

3.4 Repulsive electromagnets. courtesy (Prototype)

This electromagnet had overcome the previous problem and showed more electric

strength as compared to previous on but it cannot attract or repel the other electro

magnet when perfectly aligned one on another but when they were aligned side by side

they were able to attract each other.

Reason for failure

We felt that the reasons for low magnetic strength is due to the heavy weight of the

solenoid as the dimensions of the solenoid are 50mmdia and 300mm length.

26

3.3.3 CASE 3

An attempt is made by decreasing the wait i.e., by decreasing the length of the solenoid

so that as the wait decreases it will help the electromagnets to attract or repel each other.

There was no appreciable change in the result that is it was unable to attract the

electromagnets in there aligned position.

Reason for failure

After studying the whole work we done we felt that the perfect alignment cannot be

achieved because the electric flux generated is unable to penetrate in to the whole

solenoid due to the large diameter of it.

So this situation can be overcome easily by simply increasing the number of windings

so that the number of magnet like acting members increases, there by penetrating a little

more deep in to the solenoid and this increase the strength of the magnetic field.

3.3.4 CASE 4

The number of windings were increased from 800 to 1000 so that the magnetic power

may increase it is shown in the following figure.

3.5 Electromagnet with increased windings . courtesy (Prototype)

27

Even though the number of windings were increased it is not as effective as expected

because we were up to make powerful electro magnets to repel each other but it is not

similar to attraction repulsive force is approximately around 10times lesser than the

attractive force this is explained in detail in further chapters.

Reason for failure

As in our attempt 3 we assumed that the solution for the problem raised in it is just

increasing the number of windings. But even though we increase the number of

windings the simply form another layer on the existing one. So whatever magnetic

power generated in this windings is penetrates into the windings below and it is wasted

so.

3.3.5 CASE 5

Due to the failure of the previous designs, a new approach is done to make suspension

system. i.e., when a non conducting material is winded with a copper wire and

electricity is passed through it. Magnetic flux is generated and if we place an iron bar it

gets magnetized and poles of it will get altered and the rod is pushed out of the non

magnetic core.

This property of magnetization is used in designing a suspension system in such a way

that the non-magnetic core is connected to the wheel and the iron bar is connected to the

upper end of the vehicle i.e., frame.

As the Iron bar tries to come out of the core it starts levitating the vehicle and this

clearance is used to damp the impulses developed on the road.

It has an added advantage as compared to the previous design that is; it not only damps

the transverse vibrations but also longitudinal vibrations. This advantage is highly

applicable in case of machines where continuous vibrations arise due to the moving

parts inside it.

28

3.6 Iron bar pushing away the winded non-conducting material. courtesy (Prototype)

But this type did not work in real application because,

1) It cannot raise such a large loads

2) As the process is continued it started attracting to the core

Reasons for the failure

This process has several drawbacks like large losses of generated magnetic forces. And

more over as the Iron bar is continuously placed inside the magnetic field the bar started

acting as a permanent magnet. As a result the altering of the poles stopped and this

resulted in attraction of the bar to the non-magnetic core instead of repelling from it.

However this procedure leads to the previous attempts where to increase the magnetic

power of an electromagnet. So another attempt is to be made by varying the design to

the same property of the electromagnet.

3.3.6 CASE 6

In order to increase the magnetic power of the electromagnets, this t ime instead of

increasing the windings the diameter of the solenoid is decreased to 40mm so that more

electric field is penetrated in to the solenoid thereby increasing the magnetic strength.

29

Result

This resulted in little increase of the magnetic power but however it is not sufficient to

satisfy the required needs.

Reasons for failure

The reasons for the failure are same to that of attempt 4 i.e., even though the diameter of

the solenoid is decreased it is not sufficiently decreased to attain the required magnetic

field.

3.3.7 CASE 7

This time the diameter of the solenoid is further decreased to 20 mm so that further

penetration takes place.

The result is much more effective as compared to the previous attempts it started

attracting with about 0.3 kgf but when coming to repulsion it cannot even repel with 0.1

kgf. There

3.7 Attraction for 20mm dia. courtesy (Prototype)

It was proved that attractive force is not same to that repulsive force.

The reasons are explained below.

30

Relation between attraction and repulsion

When coming to attraction, if we place to magnets with opposite poles it starts attracting

due to these magnetic forces. During this process at every instant the new magnetic

lines of forces join the field and further attraction takes place.

3.8 Magnetic attraction. courtesy (wikipedia)

But in case of repulsion, as they are moving away from one another at every instant the

magnetic lines of forces repelling each other starts decreasing so they repel

comparatively lesser as compared to attraction.

3.9Magneticrepulsion. courtesy (wikipedia)

By the trials we made, it was observed that repulsion is around 10 times lesser than the

attraction.

31

3.3.8 CASE 8

Now that we know the relation between the attraction and repulsion the only way to

increase the repulsive power is by further increasing the magnetic power. This can be

achieved by further decreasing the diameter of the solenoid to 10mm.

By decreasing the dia to 10mm of 40mm length and when absorbed they were able to

attract each other with 0.2 kgf.

So all we need to do for further increase of magnetic strength is to increase the surface

area of the solenoid so that more windings can be winded and thus maximum magnetic

strength can be achieved.

Now an attempt is made by increasing the length of the solenoid to 120mm.

In this attempt maximum attractive force of around 0.7 kgf is achieved which is enough

to explain the availability of electromagnetic suspension system in the form of a

prototype.

These electromagnets of 10 mm dia which we made are shown below

3.10 Electromagnets. courtesy (Prototype)

Electromagnets of 10 mm diameter

and 40 mm length

32

4 FABRICATION OF SUSPENSION SYSTEM

4.1 Block diagram of the prototype courtesy (Hand Sketch)

For a prototype we were using a stand to which a battery is connected instead of

attaching it to a vehicle so that it is easy to explain the individual parts in a frame

structure instead of assembling it in a vehicle.

4.1 Components used in design

The components of Electromagnetic shock absorbers are

1. Frame Structure

2. Copper wire

3. Battery

4. Electromagnets

5. Switches

Each of the above components is explained in detail below:

4.1.1 Supporting stand structure

It is designed to support the shock absorber arrangement. All the parts are fixed in to

this frame stand with suitable arrangement. It is made up of hollow MS pipes of square

cross section which are cut and welded into I section at desired positions.

Dimensions of the I section are 20×60×20 cm.

33

4.2 M.S Stand courtesy(prototype)

4.1.2 Copper wire

Magnet wire or enamelled 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.

4.3 Winding wire (Gauge 28) courtesy(prototype)

The wire itself is most often fully annealed, electrolytic ally 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 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 "enamelled", enamelled wire is

not, in fact, coated with either a layer of enamel paint nor with vitreous enamel made of

34

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-imides), 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 fibreglass tape, and completed windings are

often vaccum impregnated with an insulating varnish to improve insulation strength and

long-term reliability of the winding.

Other types of insulation such as fibreglass 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. 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.

Why must use an insulated copper wire for coils of an electromagne t? 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.

35

The diameter of the wire is specified with its gauge number.

With increase in the gauge number the diameter of the wire decreases. As the diameter

of the wire decreases current flow and resistivity decreases and vice versa.

The wire we are using for making electromagnets is of gauge 22.it is selected because if

we decrease the gauge number diameter increases increasing the resistivity and if we

increase the gauge number the wire diameter decreases and it cannot sustain the current

of 12V and 7.5 amps we are supplying to it. It leads to overheating and burnt wires.

4.1.3 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 our design as it can be used more effectively.

36

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.

4.4 12v 7.5 amps lead acid battery courtesy (prototype)

Table 1Battery specifications

Voltage 12v

current 7.5 amp

4.1.4 Electromagnets

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 centre 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,

37

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.

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.

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 ferromagnetic 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

38

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 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 freque ncy

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.

39

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:

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 me 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 centre leg, whose section area is twice

that of each individual outer leg. A core shape derived from E shape is used in this

model.

4.1.5 Switches

For operating the circuit we were using a kill switch and a buzzer switch each of 220

volts.

A kill switch is used to cut the electricity when the circuit is over heated due to eddy

currents. It is also used to shut down or disable machinery or a device or program. The

purpose of a kill switch is usually either to prevent theft of a machine or data or as a

40

means of shutting down machinery in an emergency, and a buzzer switch is used for

allowing electricity into those windings whenever required.

4.2 Design and Assembly

As we already had all those individual parts. i.e., Stand, Frame, Battery, Wind ing wire,

Electromagnets and Kill switches. We have to design a structure with following

properties

It should with held the weight of the battery

It should be able to absorb vibrations and sudden shocks

It should not be complex in design

It should be robust

The design of the assembly consists of I sectioned stand on which battery is mounted on

one side and electromagnets are connected to this battery from the other side. These

electro magnets are dropped in to a PVC pipe in order to constrain the moment of these

electromagnets due to repulsion.

The figure of the above explanation is given below.

41

4.3 Analysis of the material used in the design

4.3.1 Mild steel

Mild steel is a very popular metal and one of the cheapest types of steel

available. It’s found in almost every metal product. This type of steel contains

less than 2 % carbon, which makes it magnetize well. Since it’s relatively

inexpensive, mild steel is useful for most projects requiring huge amounts of

steel.

Density = 7861.093 kg/m3.

Yield Strength = 250-395 Mpa.

Tensile Strength = 345-580 Mpa.

Modulus of elasticity = 200-250 Gpa.

Hardness = 107-172 HV

4.3.2 Aluminum

Density = 2700kg/m3.

Modulus of elasticity = 68.3 GPa

Tensile Strength = 70-360 Mpa.

Yield Strength = 30-286 Mpa.

Hardness = 30-100 HV

42

5 RESULTS AND DISCUSSION

At this point we have to select a battery such that it should provide maximum magnetic

strength in specific conditions. We are using 9V 1.3amps,12V 7amps and 12V 10amps

batteries and the output of the magnetic strength is noted I the table below.

The following table explains the magnetic strength deve loped for attraction when

different batteries are used with different windings. The solenoid used in this case is of

10 mm diameter and 120mm length M.S.

Table 2 Results of different trials made

Voltage Amperes Windings Kgf

9V 1.3amps 200 0.02

9V 1.3amps 400 0.04

9V 1.3amps 600 0.07

12V 7amps 200 0.3

12V 7amps 400 0.45

12V 7amps 600 0.7

12V 10amps 200 0.25

12V 10amps 400 0.3

12V 10amps 600 0.5

43

5.1 Variation of magnetic field with respect to number of windings

As from the above results we can conclude that 12V-7amps battery can achieve

maximum strength. So, using this battery we observed the magnetic strength developed

by varying the number of windings. And a graph is plotted which is shown below.

Table 3 Graph of No. of windings v/s magnetic strength in kgf

Windings 450 600 750 900 1050 1200 1350

kgf 0.45 0.7 0.7 0.71 0.72 0.73 0.69

If we observe the above graph as we increase the windings the magnetic strength of the

electromagnet increases up to some extent and from the saturation limit the magnetic

strength starts decreasing.

This is because, as the voltage we pass is constant and the length of the winding wire

goes on increasing, the resistivity inside the wire will also increased and by this the

magnetic strength starts decreasing after some extent.

In the above electromagnets we made this resistivity limit is at 1250 windings. i.e., after

this limit by increasing the windings the magnetic strength goes on decreasing.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

150 300 450 600 750 900 1050 1200 1350

mag

ne

tic

stre

ngt

h in

kgf

no. of windings

magnetic strength

44

5.2 Variation of magnetic strength with respect to diameter

Similarly by decreasing the diameter of the solenoid the magnetic strength is observed

and the graph of the attractive force is as follows.

Table 4 Graph of Dia of the Rod v/s magnetic field strength

Dia 10 20 30 40 50

kgf 0.7 0.3 0.25 0.2 0.15

As explained above by increasing the diameter of the solenoid it becomes hard for the

magnetic lines of forces to penetrate in to the solenoid so, by increasing the diameter the

magnetic strength decreases.

However if we further decrease the diameter the magnetic lines of forces collide each

other and this again results in the decrease of the magnetic field.

For the present electro magnets we can achieve maximum magnetic strength at 10mm

diameter.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

10 20 30 40 50

Mag

ne

tic

Stre

ngt

h

Diameter

Magnetic Strength

45

5.3 Variation of magnetic strength with respect to length of the solenoid

By using the same battery in order to increase the magnetic force, the length of the

solenoid is increased and the variation is observed.

Table 5 Graph of Length of Solenoid v/s magnetic strength

Length 4 5 6 7

Kgf 0.4 0.47 0.52 0.7

The above graph represents the relation between length of the solenoid and the magnetic

flux generated. As shown above with the increase in the length of the solenoid the

magnetic strength keeps on increasing.

This is due to the increase of the surface area of the solenoid i.e., with increase in the

surface area the wire is winded on the extended surface and as a result this magnetic

field increases.

This process can be continued until the resistivity inside the wire start resisting the

current and thereby decreasing the magnetic strength. As per the trials we made

maximum magnetic strength is achieved at 120 mm with 800 windings on it.

0

1

2

3

4

5

6

7

8

0.4 0.47 0.52 0.7

len

gth

in c

m

magnetic strength in kgf

Length of solenoid v/s magnetic strength

46

5.4 Variation of magnetic strength with respect to voltage

Apart from the above graphs, as we also studied the variation of the voltage keeping the current constant using a potentiometer the result is as follows.

Table 6 Graph of Voltage v/s Magnetic strength in kgf

Voltage 3 6 9 12

kgf 0.2 0.25 0.32 0.7

A graph is plotted using voltage on y-axis and magnetic strength on x-axis such that

with the increase in the voltage the magnetic strength goes on increasing. It is unlike the

previous relations i.e., the magnetic strength goes on increasing with the increase in the

voltage. But the only thing that restricts the maximum voltage is if the voltage is more it

burns the copper wire.

So we can say that voltage is directly proportional to magnetic strength.

i.e., V α F

=> V = k.F

Where, k = proportionality constant.

V = Voltage, F = Magnetic strength in Kgf .

0

2

4

6

8

10

12

14

0.2 0.25 0.32 0.7

volt

age

magnetic strength in kgf

Voltage v/s magnetic strength in kgf

47

5.5 Variation of magnetic strength with respect to current

Even though we don’t have a current altering device, from the above obtained results

we estimated the magnetic strength that could be achieved by altering thecurrent.

Table 7 Graph on Current v/s Magnetic strength in Kgf

Current 1.3 3.5 7 10

Kgf 0.13 0.26 0.7 0.42

The above graph is similar to that voltage v/s magnetic strength.

By increasing the current the magnetic strength goes on increasing. So it can be

concluded that by increasing the voltage and current at a time maximum magnetic

strength can be achieved.

We know that, V = k.F -------- (1)

From the above discussion C = a.F -------- (2)

Considering (1) & (2)

F = p.C.V

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

1.3 3.5 7 10

mag

ne

tic

stre

ngt

h in

kgf

current in amps

Current v/s magnetic strength in kgf

48

5.6 Series and parallel circuits

5.6.1 Series connection

In series connection as the 12V 7.5amps current pass through the windings of the first

electromagnet the resistivity present inside the wire will decrease the voltage up to a

larger extent and as the circuit is of series type this decreased voltage enter in to the

second electro magnet and as a result there is a difference in the magnetic flux

generated as a result

The magnetic lines of forces from one electro magnet will overcome the lines of force

of the other electromagnet. This results in decrease in magnetic strength of the electro

magnets.

5.6.2 Parallel connection

In case of parallel circuits same amount of voltage is passed through both the

electromagnets and as a result both of them attain same magnetic flux in them. So

magnetic lines of forces align perfectly and this results in increased magnetic strength.

Considering the draw backs discussed above in our project we are using parallel circuit

to overcome such losses.

5.1 Series and Parallel Circuits

When a 10mm dia solenoid is connected to 12V 7amps battery in series and parallel the

results are as follows-

Series- 0.55kgf parallel-0.7kgf

So, we can say that parallel circuit is preferable than series circuit.

49

6 ADVANTAGES

No need for continuous power.

As the electricity is continuously supplied even after the circuit is cut down the solenoid

acts like a magnet for some time. So, we can say that continuous power supply is not

necessary.

Ease of control

Once the setup is assembled there is no need to control as it is self adjustable.

Absence of fluids

As we are levitating one electromagnet on another there is no contact between them so

no need of lubricating fluids.

Increase comfort

Compared to present shock absorbers this clearance will damp the shocks and vibration

fast and smoothly. So, the comfort increases

Wear of parts

As we are completely avoiding the contact no wear of parts takes place.

50

7 CONCLUSION

7.1 Design

The proposed design is not only made for improvisation but it also focuses on different

aspects like Safety, Ride comfort, Fail Safe etc., each of them is explained below.

7.2 Safety

In general, the contact with road surface is increased. When a car turns through corner

of curves, the effect of body roll is almost eliminated. This would decrease the chance

to topple over the sides making it safer for the passenger. Also the smooth movement of

the vehicle would prevent damage of the mechanical parts.

7.1 steering mechanisam courtesy (wikipedia)

7.3 Ride Comfort

The fast response of this system is able to cancel out the vibration up to a very large

extent making it very comfortable.

7.4 Fail Safe

Even if the power supply fails, the passive spring would still absorb the shocks and the

regenerative power would help run the EM damper.

7.5 Overview

Active suspension offers many benefits over conventional and semi-active

suspension systems

Electromagnetic suspension system is a high bandwidth and efficient solution

for improving handling and comfort

51

8 BIBLIOGRAPHY

1) “Electromagnetic suspension system for vehicle patent”. Patent no US 7005816

B2, Feb 2006.

2) https://en.wikipedia.org/wiki/Electromagnetic_suspension

3) L.J.Gysen , J.J.H.Paulides, J.L.G.Janssen, E.A.Lomonova.(March 2010)“Active

Electromagnetic Suspension System for Improved Vehicle Dynamics”.IEEE

Transactions on vehicular technology, VOL. 59.

4) Rakshith.M, YathinKumar.L, Vikas.S.G, “Bose Automotive Suspension”

(September 2014). International Journal of Recent Technology and Engineering

(IJRTE) ISSN: 2277-3878, Volume-3 Issue-4.

5) M. Suresh, Walter Karg R, R. Rohith Renish and Viraal Nemani. Design and

analysis of electromagnetic suspension system for improved vehicles stability”

(january 2016).ARPN Journal of Engineering and Applied Sciences,VOL.11,

NO.2.