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FULL SEMESTER INTERNSHIP ROJECT REPORT (Project Semester, January-May 2015)

SWARAJ MAZDA LIMITED, ISUZU

(SML ISUZU, ROPAR)

PIEZO-ELECTRIC HYBRID SHOCK ABSORBER Submitted by:- Mani Pathak Reg. Id: 11104136

Department of Mechanical Engineering

Lovely Professional university of Technology, Jalandhar

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DECLARATION

I hereby declare that the project work entitled ‘Piezo-electric hybrid

shock absorber ’ is an authentic record of my own work carried out at Sml

ISUZU, Ropar as requirements of six weeks project semester for the award of

degree of B.E. Mechanical Engineering, LPU University of Technology, under

the guidance of Mr. S.K. Sharma during January-may, 2015.

DATE-5/5/2015 Name: - Mani Pathak

Sig-__________ __

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ACKNOWLEDGEMENT

Before I start with the details of my project, I would like to add a few

heartfelt words for the people who were a part of my project in numerous

ways, the people who gave me their immense support right from the stage

where I was novice to the automobile industry.

Only words are not sufficient for Mr. S.K. Sharma, Senior Manager, R&D, my

mentor and my project guide as his profound knowledge and great experience

in the heavy vehicle industry helped me a lot during my whole learning

process at Sml ISUZU. I sincerely regard his guidance, principles and teachings

and never say die attitude which has uplifted me morally many times and this

thing will also help me in my future life and I will for sure miss his charming

company in years to come. One more thing about him is his support behind me

in everything during my training period which made me so comfortable and

confident in expressing my ideas and views on important projects and issues of

the company.

I would like to thank HOD of mechanical Prof______________ and Mr

Ranjeet saraal my mentor and Prof. of Lovely Professional University for

giving me a unique opportunity to come to Sml Isuzu, Ropar.

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CONTENTSCONTENTS

Sr. no Chapter

Topic Page no

1) Declaration by student

2

2) Acknowledgement

3

3) Preface

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4) About Industry

6

5) List of figures and tables

7

6) Abstract 8

7) Chapter-1 Introduction

9

8) Chapter-2 Objective and Hypothesis of work and study

12

9) Chapter-3 Test-Research and Experimental work done

on projects

28

10) Chapter-4 Comparison and results of outcomes

37

11) Chapter-5 Conclusion

41

12) Chapter-6 Scope of further improvements in design and

performance of EMSS

42

13) Reference

50

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PREFACE

SML Isuzu is the flagship and leading internship company of around

11297.2 crore SML group which has significant presence in key

sectors of India economy. Consistently it is one of the most respected

companies in the country.

Set up in 1985 to make general purpose utility vehicles for the Indian

market SML Isuzu soon branch out in to manufacturing light,

medium & heavy commercials vehicles. The company later expanded

its operations from automobiles and tractors to secure a significant

presence in many more private sectors.

The company has over the years transformed itself into a group that

caters to the Indian and overseas markets with a presence in vehicles,

farm equipments, trade and fiancés related service and infrastructure

development.

I have worked in Assembly and R&D department and worked on

electro-magnetic power generating suspension system ,engine casting

and refinement of casting process and other.

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Introduction of company

SML Isuzu Limited (SMLI) is a trusted and reliable commercial

vehicle manufacturer since 1985. It has over 23 years of experience in

producing Light & medium commercial vehicles to meet the Indian

costumer’s needs. SMLI is a first company to manufacture and supply

state of art fully built Buses, ambulances and customizes vehicles.

Sumitomo Corporation, Japan and Isuzu Motors, Japan respectively

holds 44%and 15%shareholdings in the company. SML Isuzu

Limited was formed in 2010 from the Swaraj Mazda company

after Mazda pulled out of the venture and the Swaraj name was sold

to Mahindra when the tractor division Punjab Tractors was sold off.

The Sumitomo Corporation and Isuzu are now partners in this

company and together have produced several licensed-Isuzu products

Commercial vehicle manufacturer SML Isuzu will invest Rs 220

crore in the next three years for product improvement and up-

gradation of technology and plant infrastructure.

.

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List of figures:-

Figure 1- List of suspension system 11 Figure 2- Top part 13 Figure 3-Bottom part 13 Figure 4- Helical spring 14 Figure 5- Sketch of top part 14 Figure 6-Drafting of helical spring 14 Figure 7-Assembly 14 Figure 8-Draft of modified spring 15 Figure 9- 3-D part of modified spring 15 Figure 10- Imported Model from Pro/Engineer 15 Figure 11- Tetra Meshed Model 16

Figure 12-constraining from one end 16 Figure 13- Displacement Vector Sum 17 Figure 14- Von misses stress 17 Figure 15- Proposed design of the shock absorber 21

Figure 16- Screenshots from the CRO 26 Figure 17- Line diagram of the system 28

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Abstract The ultimate objective of this thesis is to employ existing suspension system

and damper design knowledge together with new ideas from electromagnetic

theories to develop new electromagnetic dampers. To achieve the defined

goals, analytical modeling, numerical simulations, and lab-based experiments

are conducted. A number of experimental test-beds are prepared for various

experimental analyses on the fabricated prototypes as well as off-the-shelf

dampers.

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CHAPTER: - 1

Introduction

A suspension system or shock absorber is a mechanical device designed to

smooth out or damp shock impulse, and dissipate kinetic energy. The shock

absorbers duty is to absorb or dissipate energy. In a vehicle, it reduces the

effect of traveling over rough ground, leading to improved ride quality, and

increase in comfort due to substantially reduced amplitude of disturbances.

When a vehicle is traveling on a level road and the wheels strike a bump, the

spring is compressed quickly. The compressed spring will attempt to return to

its normal loaded length and, in so doing, will rebound past its normal height,

causing the body to be lifted. The weight of the vehicle will then push the

spring down below its normal loaded height. This, in turn, causes the spring to

rebound again. This bouncing process is repeated over and over, a little less

each time, until the up-and-down movement finally stops. If bouncing is

allowed to go uncontrolled, it will not only cause an uncomfortable ride but

will make handling of the vehicle very difficult. The design of spring in

suspension system is very important. In this project a shock absorber is

designed and a 3D model is created using Pro/Engineer. The model is also

changed by changing the thickness of the spring. Structural analysis and modal

analysis are done on the shock absorber by varying material for spring, Spring

Steel and Beryllium Copper. The analysis is done by considering loads, bike

weight, single person and 2 persons. Structural analysis is done to validate the

strength and modal analysis is done to determine the displacements for

different frequencies for number of modes. Comparison is done for two

materials to verify best material for spring in Shock absorber. Modeling is done

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in Pro/ENGINEER and analysis is done in ANSYS. Pro/ENGINEER is the standard

in 3D product design, featuring industry-leading productivity tools that

promote best practices in design.ANSYS is general-purpose finite element

analysis (FEA) software package. Finite Element Analysis is a numerical method

of deconstructing a complex system into very small pieces (of user-designated

size) called elements.

The use of electromagnetic dampers in active vehicle suspension systems has

drawn considerable attention in the recent years, attributed to the fact that

active suspension systems have superior performance in terms of ride comfort

and road-handling performances compared to their passive and semi-active

counterparts in automotive applications. As a response to the expanding

demand for superior vehicle suspension systems, this thesis describes the

design and development of a new electromagnetic damper as a customized

linear permanent magnet actuator to be used in active suspension systems.

The proposed electromagnetic damper has energy harvesting capability.

Unlike commercial passive/semi-active dampers that convert the vibration

kinetic energy into heat, the dissipated energy in electromagnetic dampers can

be regenerated as useful electrical energy. Electromagnetic dampers are used

in active suspension systems, where the damping coefficient is controlled

rapidly and reliably through electrical manipulations

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Fig:1-Classification of suspension systems

Suspension system

Active

Hydraulic

Pneumatic

Electro-magnetic

Passive

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CHAPTER:-2 Hypothesis of work

Designing of shock absorber in Pro Engineering ENGINEERING DESIGN Pro/Engineer offers a range of tools to enable the generation of a complete

digital representation of the product being designed. In addition to the general

geometry tools there is also the ability to generate geometry of other

integrated design disciplines such as industrial and standard pipe work and

complete wiring definitions. Tools are also available to support collaborative

development. A number of concept design tools that provide up-front

Industrial Design concepts can then be used in the downstream process of

engineering the product. These range from conceptual Industrial design

sketches, reverse engineering with point cloud data and comprehensive

freeform surface tools. DIFFERENT MODULES IN PRO/ENGINEER

PART DESIGN

ASSEMBLY

DRAWING

SHEETMETAL

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MODEL OF SHOCK ABSORBER PARTS OF SHOCK ABSORBER

Fig.2- BOTTOM PART

Fig.3-TOP PART

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Fig.5-sketch of top part

Fig.4-helical spring

Fig.6-Drafting of helical spring

Fig.7-ASSEMBLY

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Fig.8-draft of MODIFIED SPRING

Fig.9-3D part of modified spring

Ansys analysation-In FEM (finite element analysis)

Fig.10-Imported Model from Pro/Engineer

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Fig.11- Tetra Meshed Model

Fig.12-constraining from one end

Spring Steel as spring material Case: Load 125kgs Element Type Solid 20 node 95 Material: Spring Steel Material Properties: Young’s Modulus (EX): 210000N/mm2 Poisson’s Ratio

(PRXY): 0.29 Density: 0.000007850kg/mm3

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RESULTS AFTER APPLIENG LOADS:

Fig.13-Displacement Vector Sum

Fig.14-Von misses stress

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EMSS (Electro-magnetic suspension system)

PIEZO ELECTRIC POWER GENERATING SHOCK ABSORBER

When used in a vehicle or hybrid electric vehicle the electricity generated by

the shock absorber can be stored in the battery to be used later. In non-

electric vehicles the electricity can be used to power accessories such as air

conditioner which attains around 5-6% of engine power and also reduce the

load on alternator which needs about 3-5% of engine power. The two designs

that we had considered for conserving energy from shock absorber are:

1) Electromagnetic

2) Hydraulic

ELECTROMAGNETIC

The design consists of two tube-like components - a hollow copper coil

assembly and a magnet that uses vibration of the vehicle’s suspension to move

up and down inside it. When the vehicle is in motion, the vibration in the

suspension causes the coil to move relative to the magnet. As the copper coil

moves inside this magnetic field, a voltage is generated.

But this design is not much efficient due to the losses. The power is lost in the

form of eddy current loss and hysteresis loss. Also the system tends to be

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bulky and cannot be successfully implemented in smaller shock absorbers of

two wheelers.

HYDRAULIC

This design consists of a hydraulic system that forces fluid through a tiny

turbine attached to a dynamo. Each time the shock absorber compresses, the

fluid is forced through the turbine causing it to rotate. Thus energy is

generated in the coupled dynamo. The main disadvantage of this method is

that it can be used only in heavy vehicles.

CONCEPT

In our design, the energy is regenerated using a piezoelectric crystal. A

piezoelectric crystal is installed within the shock absorber. When the shock

absorber is compressed, force is transmitted to the piezoelectric crystal. Thus

electric energy is obtained from the shock absorber. The force transmitted to

the piezoelectric crystal is limited to the safe range of the material by using

suitable damping mechanism. The design considerations of the piezoelectric

shock absorber are explained in the next chapter.

The piezoelectric regenerative shock absorber can be used in any vehicle,

irrespective of size ranging from two wheelers to trucks. Piezoelectric crystal

of appropriate size is fixed on the shock absorber. By recovering the vehicle’s

energy lost in vibration, the piezoelectric regenerative system will be able to

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increase fuel efficiency in a hybrid or electric powered vehicles. In other

vehicles the pulsating voltage obtained from the shock absorber can be

rectified by using a rectifying circuit and can be used to charge the battery.

This can be used to power other accessories in the vehicle.

DESIGN

A cylindrical shaped piezoelectric material (PZC), made of Lead Zirconate

Titanate Ceramic, commercially known as DCPL-5 is fixed within the shock

absorber, with suitable damping so that only a part of the total force

generated while shock absorber compression is transmitted to the PZC,

sufficient enough to generate the optimum voltage, with a constraint on the

maximum endurance strength of the material. Ceramic PZCs usually have high

compressive yield stress. The rough arrangement of components will be as

shown-

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Fig15. Proposed design of the shock absorber

(The outer spring is omitted in the diagram to show the inner

components)DCPL-5

It is a modified Lead Zirconate Titanate Ceramic, providing transducer

elements with high electro mechanical coupling coefficient and high charge

sensitivity and curie temp of 350 º C, used for sensing applications like

ultrasonic flaw detection, under water echo sounding, pressure gauges, strain

gauges, accelerometers, medical Instruments, flow meters, NDT systems, Level

gauges and many other devices. Our model was developed using this crystal,

which was sent to us by Mr. Sunil Kapoor, Doon Ceratronics Pvt. Ltd,

Dehradun, on request.

The properties of the PZC is tabulated as-

PZC

Bush

Spring

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Properties Symbol DCPL-5

Piezoelectric Coupling Coefficients Kp .60

K33 .70

K31 .32

Piezoelectric Charge Coefficients(x 10-12 C/N)

d33 425

d31 -170

Piezoelectric Voltage Constants (x 10-3 Vm/N)

g33 25

g31 -11

Dielectric Constant at 1Khz

KT33 1750

Dissipation Factor

.02

Mechanical Quality Factor

Qm 75

Density (Kg/m3)

7650

Curie Temperature (Tc) °C

350

Frequency Constants(Hz-M)

Np 1950

Important factors governing performance are the shape of the PZC transducer,

the manner in which the transducer is mounted and, of course, the nature of

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the electrical load. A PZC disk for example, compressed between two metal

surfaces will never be able to expand in the radial direction as readily as would

a long, thin cylinder, which is only constrained at its ends and assumes a barrel

shape on radial expansion. So the way in which the material is mounted will

directly affect the energy conversion per unit volume. The general rule

therefore is to allow the PZC body some freedom to expand radially since

charge generation is directly coupled to deformation.

ANALYSIS-performance based physical properties

Assuming the force on the PZC to be static, the following analysis is carried

out

Consider a PZC cylinder of height h, polarized in the axial direction and with

electrodes on its end faces. If an axial stress T3 is applied, it will deform and

hence charge will displace toward the electrodes. Under open circuit

conditions (D = 0) the voltage U3 is given by:

(T3=axial stress applied)

V 3 = - g33hT3 -- (1) (h=height of PZC material)

(g33=piezo electric constant)

A compressive stress (negative sign) will therefore generate a positive voltage

across the transducer. To get an idea of the order of magnitude of the voltage

to be expected, a 10 mm Lead zirconatetitanate cube (g33 = 22 x 10-3 Vm/N)

subjected to a force of 5kN will generate a voltage about 11 kV. The total

energy WD fed into a PZC element by a mechanical source can be split up as

follows: (no losses, open circuit)

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W D = Wm + We -- (2)

Where: Wm = mechanical deformation energy

We = energy stored in the electrical field in the ceramic.

The latter may be withdrawn from the element as electrical energy.

The energy WD can be simply expressed in terms of compliance SD and the

mechanical stress T by:

In which V is the volume of the PZC element. We and Wm are given in terms of

the coupling coefficient k33 by:

These equations show that for given material properties only V and T govern

the energy conversion. If, therefore, in a particular application the force that

=

=

=

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can be applied is limited, the electrical energy generated can be increased by

choosing a smaller surface area (equal volume). For example one can use a

long thin cylinder instead of a short thick one.

PZC-elements under compressive stress in open circuit conditions do not suffer

from depolarization. The induced field has the same direction as the poling

field during polarization and the voltage increases almost linearly with the

stress even up to very high load levels.

Fig 4.2. Charge density on PZT5A discs as a function of compressive load. The

discs (h = 5 to 16 mm) were clamped between two steel plates.

The PZC, springs and bushes are fixed on the shock absorber in such a way that

the total stiffness and hence the performance of the shock absorber as a

whole is not affected.

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RESULT

The present model was tested with CRO to find out the output. The screen

shots of the CRO was taken into consideration and the results are as follow.

Fig16. Screenshots from the CRO

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The X- axis shows time in milliseconds and Y- axis shows voltage in volts. The

energy generation is limited to a few fraction of a second, when the impact

loading takes place.

The graphs show a peak generated voltage of up to 25 V, when subjected to

shock manually. The voltage generated depends on the force applied.

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CHAPTER:-3

Test-Research and experimentation done on work

Test-comparison in performance of typical unmodified shock

absorber to that of modified (pzc)

Typical shock absorber can be shown by the following line diagram:-

Fig 17. Line diagram of the system

Where K is the stiffness of the outer spring and c is the damping coefficient of

the dashpot (air chamber).

This is a problem of forced vibration relating the sprung and unsprung masses

of vehicle. Suppose we have an impressed oscillating force F=F0sinωt, causing

a displacement x1 which is a function of time, t.

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ner a force m

amping force c

Spring force = kx

Thus equation of motion will be-

m c + kx - F0sinωt 0

r m c + kx = F0sinωt

The complete solution of the equation consists of two parts, the

complementary function (CF) and the particular integral (PI).

CF = Xe-ξωnt sin (ωdt Φ1)

Where,

X and Φ1 are determined from the initial conditions, ξ is the damping factor, ωn

is the natural frequency of the system, ωd is the damping frequency which is

related to ωn as :-

ωd =

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To obtain the PI, let c/m=a, k/m=b and F0/m =d

Then using the operator D, the equation becomes,

(D2 a b) d sinωt

PI =

PI =

=

=

Taking RcosΦ and aω RsinΦ, on further simplification yields :-

PI =

x = CF + PI

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x = Xe-ξωn

t sin(ωdt+Φ1) +

-- (1)

This is the equation of displacement of an unmodified shock absorber.

Now we introduce the new components within the shock absorber to

incorporate the PZC.

Let the collective stiffness of the PZC, the two bushes and the two springs be

Ke

where,

Kp is the stiffness of the PZC

Kb is the stiffness of the bushes

Ks is the stiffness of the spring.

The modified line diagram will be as :-

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Fig 4.4. Line diagram of the modified system

Suppose we have the same impressed oscillating force F = F0sinωt, causing a

displacement x1 which is a function of time, t.

ner a force m 1

amping force c 1

Spring force = K1x1

Force due to the new system = Kex1

Thus equation of motion will be-

K

1

Ke

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m 1 c 1 + (K1+Ke)x1 - F0sinωt 0

or m 1 c 1 + (K1+Ke)x1 = F0sinωt

The complete solution of the equation consists of two parts, The

complementary function (CF) and the particular integral (PI).

CF = X1e-ξ1ω

n1t sin(ωd1t Φ1)

Where,

X1 and Φ1 are determined from the initial conditions, ξ1 is the damping factor,

ωn1is the natural frequency of the system, and ωd1 is the damping frequency

which is related to ωn as :-

ωd1 =

To obtain the PI, let c/m=a, k/m=b and F0/m =d

Then using the operator D, the equation becomes,

(D2 a b) d sinωt

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PI =

PI =

=

=

Taking RcosΦ and aω RsinΦ, on further simplification yields :-

PI =

x1 = CF + PI

x1 = Xe-ξ1ωn1

t sin(ωd1t Φ1) +

-----

2

The spring displacements in the two cases should be the same. Hence (1) = (2),

which implies,

K = K1 + Ke or K1 = K - Ke

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Test-design of spring without change in cost, change in

materialist properties and without a change in diameter of

the spring.

So, what are the left variable factors by which we can change the properties

of a spring?

That is only the no of turns

By measured data we have,

Stiffness of Original the outer spring, K = 12.80 N/mm

Combined stiffness of the inner springs, bushes plates and PZC, Ke =

2.25N/mm

We design a new outer spring of stiffness K1 = K – Ke. The length and diameter

of the spring remains unchanged.

Number of turns of the original spring = 17

Number of turns n =

G = N/

d = 7mm

D= 28mm

K1 = 12.8 – 2.25 = 10.55N/mm

On solving we get, n =18.197

n’ = n+2 = 21 turns (for squared and ground ends)

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Thus the outer spring, currently in use is replaced by another spring of the

same material and dimensions with a slight change in the number of turns.

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CHAPTER: - 4

Comparison and results of outcomes

COMPARISON OF SHOCKS.

These notes identify the high force that can result from and impact and the

show the reduction in force by use of a spring and a compensating hydraulic

shock absorber. The example is provides as a general illustration and is very

much simplified.

4.1)Force resulting from impact with no shock absorber included

Considering a very simple duty of dropping a 1 kg load through 1m onto a

machine element represented by a short steel column 0.1m dia by 0.2m long

made form steel.

Fig AII.1.

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The stiffness of the column k = AE / l.

A = 0.00784m2

E = 21x1010 Pa (N/m2)

l = 0.2m

The stiffness of the column k is the Load /unit deflection is calculated as:-

k = 0.0784 21 1010 /0.2 = 8.25 1010N/m

To calculate the maximum force resulting from the dropped load assuming

conservation of energy.

The strain energy absorbed by the column = the Potential energy absorbed

from the dropped load. The potential energy of the load = E 1

E 1=Mgh = 4.905 Nm.

This equals the strain energy absorbed by the load at impact

The strain energy absorbed = Pmaxδmax /2 = Pmax2 / 2 k

Therefore to calculate the maximum force developed Pmax

Pmax = Sqrt (2.E1.k) = Sqrt (4.905 8.25 1010 ) = 899kN

Maximum force Resulting From Use of Spring

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If a spring with a stroke of 0.1m is located on the top surface as shown below

Fig AII.2

The resulting maximum force is determined as follows.

Energy to be absorbed = E1 = Mgh. = 4.905 Nm

Strain energy of spring Fδspring /2

Therefore Ma imum force 2Mgh/δspring = 98.1N

Use of the spring has reduced the maximum force by a factor of 10. However

the spring is now exerting an upwrd force which will cause the load to rebound

upwards. Detailed analysis of the system response is required to arrive at the

total motion history of this event

Maximum force resulting from the use of a compensating Hydraulic

Shock absorber

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If a Shock absorber with a stroke of 0.1m is located on the top surface as

shown below -

Fig

It is assumed that the shock absorber is designed to provide a constant

deceleration force throughout its stroke..

The resulting maximum force is determined as follows.

Energy to be absorbed = E1 = Mgh. = 4.905 Nm

Energy to be dissipated in the shock absorber Fδsh_ab

Therefore Ma imum force Mgh/δsh_ab = 49.05 N

The energy has been dissipated in heating up the hydraulic fluid in the shock

absorber. When the load has come to rest the system is in a stable state. The

maximum force transmitted to the column during impact is 1/20 that

experienced by without the shock absorber.

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CHAPTER:-5

CONCLUSION OF THE WORK PERFORMED.

The use of piezoelectric crystal in the shock absorber is a new method for

power generation. By using PZCs, power could be generated more effectively

than that compared to electromagnetic and hydraulic type generation. The

piezoelectric regenerative shock absorber can be commercialized for the use in

vehicles. Also the cost involved is very low which makes it economically

efficient. This technology can be efficiently implemented in conventional

vehicles as well as electric and hybrid vehicles, which will be the future of

automobile industry.

The energy regenerated by the shock absorber by this method can be found

out by calculating the current being produced. In order to calculate current,

the Voltage vs. Time curve needs to be a continuous curve, for which a

continuous load has to be applied without damaging any of the components

designed in the shock absorber, especially the piezoelectric material.

The damping system can also be further improved by providing the optimum

stress for maximum energy generation within the safe range of the ultimate

stress of piezoelectric crystal. There is still room for a lot of improvement with

this concept. It can be used in all vehicles to conserve the energy that goes

waste, which though small, will be precious in the years to come, thus

turning potholes into energy advantage that reduces the load of alternator

and A/C unit accounted for about 6-7% of total energy consumed.

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CHAPTER: -6

Scope of further improvements in design and

performance of EMSS

MULTILAYER GENERATORS

The technique developed to make multilayer capacitors can also be used for

piezoelectric ceramics. Thin layers of so called green ceramic are interleaved

with silver-palladium electrodes, compacted, cut to size and then sintered.

With these devices, the large total surface area per unit volume means that

the generated charge is high whereas the voltage is rather low. These types of

generator are ideal for use as a solid state battery for modern electronic

circuits.

Fig . Multilayer piezoelectric material

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Output voltage as a function of compressive load

These multilayer piezoelectric crystals can be used in place of bulk ceramic for

higher energy generation.

Hybrid Damper Design Conceptual Design After having investigated the electromagnetic and eddy current damping

concepts, the feasibility of adding passive damping to an active

electromagnetic damper in a hybrid active suspension is studied in this

chapter. Fig. 5-1 shows the block diagram of a hybrid electromagnetic single-

wheel suspension system. The electromagnetic actuator and the passive

damper form the hybrid electromagnetic unit. The electromagnetic portion of

the system is the only source of variable damping. The passive damping,

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caused by hydraulic/eddy current forces, provides the required level of

damping. This is to ensure that, in the event of an electrical failure, a minimum

level of damping is available from the passive portion of the system. The active

electromagnetic actuator operates in passive/active modes, allowing partial

energy recovery from the vehicle vibration. This configuration allows the use

of a smaller and lighter electromagnetic actuator, retaining the performance

level of active suspension systems.

After driving the damper design requirements in Chapter 2, two configurations

are proposed for the hybrid damper design in this chapter. The first

configuration utilizes hydraulic forces to provide the essential passive

damping, while the second design operates based on the eddy current

damping phenomenon. As mentioned previously, the passive damping in

hybrid dampers makes the suspension system, fail-proof, reduces the amount

of energy consumption in an active suspension system, and allows for a lighter

and less expensive active suspension system.

Configuration One: Mono-tube Electromagnetic/Hydraulic

Modern hydraulic dampers consist of both twin-tube and mono-tube types.

Mono-tube shock absorbers consist of a single cylinder filled with oil, and a

piston with an orifice moving through the cylinder. Fig. 5-2 depicts the first

proposed configuration as the electromagnetic/hydraulic hybrid damper.

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Stator Coil

Pressure Chamber

Reservoir

Mover

Extension Chamber

Spacer (Pole Piece)

Permanent Magnet

Stator Iron Core

Floating Piston

Fig. Schematic view of the mono-tube hybrid electromagnetic/hydraulic damper.

The electromagnetic subsystem comprises a linear tubular permanent magnet

motor with moving magnets. The moving magnets attached to the rod and

their gap with the stator coils form the piston and its orifice in the hydraulic

subsystem. The fluid movement causes a pressure drop between the

compression chamber and the extension chamber, resulting in a drag force to

be exerted through the rod. Pressurized gas is included in the damper, either

in an emulsion with the oil or separated from the oil with a floating piston in a

compressible accumulator-like chamber. The gas chamber allows the

volume of the piston rod to enter the damper without causing a hydraulic lock.

The gas also adds a spring effect to the force generated by the damper and

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maintains the damper at its extended length when no force is applied

(Gillespie, 2006).

Mono-tube dampers are typically simpler for manufacturing compared to

the twin-tube ones, but require higher gas pressures to operate properly.

Although twin-tube dampers are more complex, they operate with lower gas

pressure and are not as susceptible to damage. The electromagnetic and

hydraulic subsystems of the hybrid damper are discussed above.

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Configuration Two: Electromagnetic/Eddy Current

Another alternative configuration for the hybrid damper is shown in Fig. utilizing the

eddy current damping effect to provide the required passive damping effect.

Outer Magnet

Stator Coil

Mover

Permanent Magnet Stator Iron Core

Conductor

Spacer (Pole Piece)

Fig. Schematic view of the hybrid electromagnetic/eddy damper.

As illustrated in Fig. 5-3, the damper consists of an inner linear tubular electromagnetic

motor as the active part of the damper and a source of the variable damping. The

motor’s stator tube is encircled by a conductor tube. There is another outer Permanent

Magnet (PM) annular part that moves relative to the aforementioned conductor tube,

generating eddy currents in the conductor. The induced eddy currents generate a

repulsive damping force proportional to the relative velocity of the conductor and

magnets, causing a passive viscous damping effect.

The hybrid damper design continues with an electromagnetic analysis, followed by the

design of electromagnetic subsystem dimensions. Then, a general methodology for the

hydraulic damper design is discussed, following by the final design of the first hybrid

damper. Finally, the eddy current damping effect in the second hybrid damper

configuration is investigated, and its final design is Basic Idea.

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MULTI-HYBRID SYSTEM DESIGN

To combine the use of both Active and Passive suspension. The general Macpherson

system can be used and the passive shock absorber can be replaced by electromagnetic

dampers.

Basic Components

• Electromagnetic Damper

• Passive Coil Spring

• Power supplier

• Control Unit

presented based on the aforementioned design requirements.

General Modification It has to be made into a cylindrical shape or moreover a tubular shape so that it can be adjusted in Macpherson system

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REFERENCES

1. www.piezomaterials.com

2. www.ryston.cz/pdf/avx/piezo.pdf