DYNAMIC ANALYSIS OF TRAMCAR SUSPENSION SYSTEM …eprints.utm.my/id/eprint/9631/1/MuhammadSaifuddinMFKM2006.pdfof avoiding a very low natural frequency assimilated to motion sickness

DYNAMIC ANALYSIS OF TRAMCAR SUSPENSION SYSTEM

MUHAMMAD SAIFUDDIN BIN MOHAMED REHAN

A project report submitted in partial fulfilment of the

requirements for the award of the degree of

Master of Engineering (Mechanical)

Faculty of Mechanical Engineering

Universiti Teknologi Malaysia

MAY, 2006

iii

DEDICATION

To my beloved mother and father, my wife, and my baby boy

iv

ACKNOWLEDGEMENT

In preparing this thesis, I was in contact with many people, researchers,

academicians, and practitioners. They have contributed towards my understanding

and thoughts. In particular, I wish to express my sincere appreciation to my main

thesis supervisor, Professor Madya Mustafa Yusof, for encouragement, guidance,

critics and friendship. I am also very thankful to my co-supervisor Professor Dr.

Roslan Abd. Rahman for his guidance, advice and motivation. Without their

continued support and interest, this thesis would not have been the same as presented

here.

A special thank you also goes to Professor Madya Pakharuddin b. Mohd

Samin for his help and guidance. My fellow postgraduate students should also be

recognised for their support. My sincere appreciation also extends to all my

colleagues and others who have provided assistance at various occasions. Their

views and tips are useful indeed. Unfortunately, it is not possible to list all of them in

this limited space. I am grateful to all my family members.

v

ABSTRACT

Suspension system plays an important role in the performance of a vehicle,

especially the vehicle handling and ride comfort. The objective of this project is to

analyse the passenger ride comfort of a tramcar manufactured by UTM. Numerical

analysis was performed on the tramcar suspension system, where the system was

modelled and simulated. A full car model was successfully developed, and validated

using available experimental data from the work published by other researcher.

MATLAB Simulink software was used to simulate the system and obtain the system

response. The comfort level was evaluated based on the displacement and

acceleration response, considering the bouncing, pitching and rolling factors. The

simulation results for tramcar suspension system were then evaluated by comparing

them with simulation results for Proton Waja 1.6 and available standards. Based on

the evaluation, the conclusion on the tramcar ride comfort was made. It was

concluded that the tramcar ride comfort is comparable to the ride comfort of a Proton

Waja, and is at an acceptable level. The role of suspension spring stiffness in relation

to ride quality was also analysed. From the suspension parameter analysis, it was

concluded that the ride comfort of the tramcar can be improved to an optimum level

by having the lowest practical spring stiffness value. The tramcar suspension spring

stiffness was said to be already in the region of the lowest practical value in the sense

of avoiding a very low natural frequency assimilated to motion sickness. Some

suggestions have been made at the end of the report for possible improvement or

extension to this study.

vi

ABSTRAK

Sistem gantungan memainkan peranan penting dalam pencapaian sesebuah

kenderaan, terutamanya kawalan kenderaan dan keselesaan perjalanan. Objektif

projek ini adalah untuk menganalisa keselesaan perjalanan penumpang bagi sebuah

tramcar yang telah direkabentuk oleh UTM. Bagi mencapai objektif ini, analisa

dinamik telah dijalankan ke atas sistem gantungan tramcar tersebut. Analisa

numerikal telah dijalankan di mana satu model ‘full car model’ kepada sistem

gantungan tramcar tersebut telah berjaya dibentuk dan disimulasikan. Simulasi ke

atas model berkenaan telah dijalankan dengan menggunakan perisian MATLAB

Simulink. Tahap keselesaan penumpang telah dianalisa melihat kepada reaksi

anjakan dan pecutan, mengambil kira faktor ‘bouncing’, ‘pitching’ dan ‘rolling’.

Keputusan simulasi ke atas sistem gantungan tramcar tersebut telah dinilai

berdasarkan keputusan simulasi untuk Proton Waja 1.6 dan juga penemuan pengkaji

lain. Daripada penilaian yang dibuat, telah disimpulkan bahawa tahap keselesaan

tramcar adalah setanding dengan tahap keselesaan Proton Waja, dan berada dalam

tahap yang baik. Hubung kait antara kekenyalan spring dengan keselesaan perjalanan

turut dianalisa. Daripada keputusan analisa, dirumuskan bahawa keselesaan

perjalanan boleh ditingkatkan ke tahap optimum dengan mengurangkan kekenyalan

spring ke tahap yang terendah. Kekenyalan spring sistem gantungan tramcar didapati

telahpun berada di paras paling rendah sebelum frekuensi menjadi terlalu rendah

yang akan menyebabkan ketidak selesaan. Beberapa cadangan telah dikemukakan

pada akhir laporan berkenaan kemungkinan-kemungkinan untuk melanjutkan lagi

kajian yang telah dibuat.

vii

CONTENTS

CHAPTER TITLE PAGE

TITLE PAGE i

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES xii

LIST OF FIGURES xiv

LIST OF SYMBOLS xix

LIST OF APPENDICES xxiii

CHAPTER 1 INTRODUCTION 1

1.1 Objectives 4

1.2 Scope of the Project 4

1.3 Research Methodology 5

1.3.1 Literature Review 6

1.3.2 Numerical Modelling 6

1.3.3 Model Validation 6

1.3.4 Model Updating 6

1.3.5 Collecting the Geometry Data and Tramcar

Properties 7

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1.3.6 Numerical Simulation 7

1.3.7 Ride Comfort Evaluation 7

1.3.8 Suggestion of Improvement 7

1.4 Outline 8

CHAPTER 2 LITERATURE REVIEW 9

CHAPTER 3 BACKGROUND THEORIES 16

3.1 Definition and Terminology 16

3.1.1 Vehicle Axis System 16

3.1.2 Terminologies 17

3.2 Classification of Suspension System 18

3.2.1 Dependent Suspension 18

3.2.2 Independent Suspension 19

3.3 Types of Suspension System 19

3.3.1 Hotchkiss rear suspension 19

3.3.2 Four Link 20

3.3.3 De Dion 21

3.3.4 Trailing Arm Suspension 22

3.3.5 SLA Front Suspension (also known double

wishbones suspension) 22

3.3.6 MacPherson Strut 23

3.3.7 Multi-Link Rear Suspension 25

3.4 Suspension Components 26

3.4.1 Springs 26

3.4.1.1 Leaf springs 26

3.4.1.2 Coil springs 27

3.4.1.3 Torsion bars 28

3.4.1.4 Hydropneumatic springs 28

3.4.2 Dampers 29

3.5 Ride Quality 29

3.5.1 Excitation Sources 30

3.5.2 Vehicle Response Properties 30

ix

3.5.3 Perception of Ride 31

3.5.4 Ride Comfort Assessment 33

3.6 The Role of a Vehicle Suspension 37

3.7 Suspension Parameters 38

3.8 Modelling and Simulation 41

3.8.1 Suspension System Model 41

3.8.2 Block Diagram 45

3.8.3 Model Validation 46

3.9 Conclusion 46

CHAPTER 4 MODELLING AND SIMULATION OF TRAMCAR 47

4.1 Numerical Modelling 48

4.1.1 Quarter Car Model 48

4.1.2 Half Car Model (Pitch) 51

4.1.3 Half Car Model (Roll) 55

4.1.4 Full Car Model 59

4.2 Simulation Analysis on Tramcar Suspension System 69

4.2.1 Analysis Conditions 69

4.2.2 Input parameters for Tramcar 71

4.2.3 Assumptions 73

CHAPTER 5 MODEL VALIDATION AND COMPARATIVE STUDY 74

5.1 Model Validation 74

5.1.1 Analysis Condition and Input Parameters 75

5.1.2 Simulation Results 77

5.1.2.1 Pitch Mode 78

5.1.2.2 Roll Mode 80

5.1.3 Conclusion of Model Validation 81

5.2 Comparative Study 83

5.2.1 Ride Comfort Evaluation Based on Vehicle

Comparison 83

5.2.2 Ride Comfort Evaluation based on Available

Standards 84

x

5.2.3 Comparative Study on the Effects of

Suspension Parameters 84

5.2.4 Comparative Study on the Effects of Sprung

Mass 84

5.3 Comparison between simulation results for Tramcar

and for Proton Waja 1.6 85

5.3.1 Pitch mode bump test simulation 87

5.3.2 Roll mode bump test simulation 91

5.4 Comparison between Simulation Results with

Available Standards 93

5.4.1 Evaluation on tramcar displacement

response 95

5.4.2 Evaluation on tramcar acceleration response 97

5.5 Comparison between Simulation Results for

Different Suspension Parameters 98


5.5.2 Roll mode bump test simulation 101

5.6 Comparison between Simulation Results for Different

Sprung Mass 104



5.7 Comparative Study Results Discussions 107

5.7.1 Comparison between tramcar and Proton Waja 107

5.7.2 Comparison of Simulation Results with Ride

Quality Benchmarks 108

5.7.3 Comparison for Different Suspension Spring

Stiffness Values 109

5.7.4 Comparison for Different Sprung Mass Values 110

xi

CHAPTER 6 CONCLUSION AND RECOMMENDATION 111

6.1 Summary 102

6.2 Conclusion 103

6.2 Recommendation for Future Work 104

xii

LIST OF TABLES

TABLE NO. TITLE PAGE

3.1 Recommended criterion relationship 35

3.2 Approximated indications of likely reactions to various

magnitudes of overall vibration total values in public

transport, ISO 2631-1/97 36

3.3 Suspension parameters for various types of vehicles 39

4.1 Input parameters for tramcar and Proton Waja 1.6 used in

Simulink simulation 71

5.1 Input parameters of Proton Waja suspension system used in

Simulink simulation for both pitch and roll modes 76

5.2 Vehicle geometries of the tramcar and Proton Waja 1.6 85

5.3 Vehicle geometries of the tramcar and Proton Waja 1.6 86

5.4 Displacement and acceleration RMS values and response

frequencies for both pitch mode and roll mode bump test 94

5.5 Displacement amplitudes corresponding to subjective

responses indicated by Figure 5.25 for the frequency of

1.074Hz 96

5.6 Displacement amplitudes corresponding to reactions to

vertical vibration indicated by Figure 5.26 for the

frequency of 1.074Hz 96

5.7 RMS acceleration corresponding to reactions to human

tolerance limits for vertical vibration by Figure 5.27 for the

frequency of 1.172Hz 98

xiii

5.8 RMS displacement and acceleration values for different

suspension spring stiffness 101




passenger loadings 105


passenger loadings 107

xiv

LIST OF FIGURES

FIGURE NO. TITLE PAGE

1.1 The tramcar as viewed from various angles; the front view

of the tramcar, the rear view of the tramcar, the passenger

seating in the tramcar, and the interior view of the

driver’s compartment 3

1.2 Research methodology flow-chart 5

3.1 SAE Vehicle Axis System 17

3.2 The Hotchkiss rear suspension 20

3.3 The four-link rear suspension 21

3.4 The de Dion rear suspension 22

3.5 The trailing arm independent suspension 22

3.6 The double wishbone suspension 23

3.7 The MacPherson and modified MacPherson strut suspension 24

3.8 The (modified) MacPherson strut suspension 24

3.9 The multi-link rear suspension of the Ford Taurus and Sable 25

3.10 Leaf Spring types 27

3.11 Coil springs 28

3.12 Principles of a hydropneumatic suspension spring 28

3.13 Damper types; dual tube damper, free-piston monotube

damper 29

3.14 The ride dynamic system 30

3.15 Human tolerance limits for vertical vibration 32

3.16 Human tolerance limits for fore/aft vibrations 32

xv


3.18 Subjective response of the human body to vibration motion 34

3.19 Human reaction to vertical vibration 35

3.20 Health guidance caution zones, ISO 2631-197 36

3.21 Passive and semi-active quarter car model used by Hudha 41

3.22 Two degree of freedom half vehicle model used by Vetturi 42

3.23 A two degree of freedom half car model used by Buarque 43

3.24 A half vehicle model 43

3.25 Six degree of freedom full car model used by Stone 44

3.26 Seven degree of freedom full vehicle model used by Gaid 44

3.27 New quarter car model developed by Hong 45

4.1 Quarter car model with two degree of freedom 48

4.2 Free body diagram of sprung mass 49

4.3 Free body diagram of unsprung mass 49

4.4 Overall block diagram for the suspension system 50

4.5 Overall Simulink diagram for the suspension system 51

4.6 Simulink diagram for subsystem – Calculation of vertical

displacement against time 51

4.7 Half car model (pitch) with four degree of freedom 51


4.9 Free body diagram of front and rear unsprung mass 53

4.10 Overall Simulink diagram for the half car model of the

suspension system 54

4.11 Simulink diagram for subsystem – Calculation of vertical


4.12 Half car model (roll) with four degree of freedom 55


4.14 Free body diagram of right and left unsprung mass 57

4.15 Overall Simulink diagram for the half car model of the

suspension system 58

4.16 Simulink diagram of subsystem – Calculation of vertical


4.17 Full vehicle model with seven degree of freedom 59

xvi

4.18 Simulink diagram for the full car model of the suspension

system 64

4.19 Subsystem of calculation of vertical displacement over time 65

4.20 Subsystem of calculation for front right suspension system 65

4.21 Subsystem of calculation for front left suspension system 66

4.22 Subsystem of calculation for rear right suspension system 66

4.23 Subsystem of calculation for rear left suspension system 67

4.24 Subsystem of calculation for sprung mass vertical

displacement 67

4.25 Subsystem of calculation for sprung mass pitch angle 68

4.26 Subsystem of calculation for sprung mass roll angle 68

4.27 Pitch mode bump test 70

4.28 Roll mode bump test 70

4.29 The force-displacement characteristic of the tramcar

suspension spring 72

4.30 The force-velocity characteristic of the tramcar suspension

damping 72

4.31 The force-displacement characteristic of the Waja 1.6

suspension spring 72

4.32 The force-velocity characteristic of the Waja 1.6 suspension

damping 73

5.1 3D view of pitch mode and roll mode bump test performed

by Hudha 76

5.2 The force-displacement characteristic of the suspension

spring 77

5.3 The force-velocity characteristic of the suspension damping 77

5.4 Front right sprung mass acceleration 78

5.5 Front left sprung mass acceleration 78

5.6 Rear right sprung mass acceleration 79

5.7 Rear left sprung mass acceleration 79

5.8 Pitch rate at body centre of gravity 79

5.9 Sprung mass acceleration at body centre of gravity 80

5.10 Front left sprung mass acceleration 80

xvii

5.11 Rear left sprung mass acceleration 81

5.12 Roll rate at body centre of gravity 81

5.13 Sprung mass displacement at body centre of gravity 87


5.15 Sprung mass pitch angle at body centre of gravity 89

5.16 Sprung mass pitch rate at body centre of gravity 89

5.17 Sprung mass displacement at body centre of gravity 91


5.19 Sprung mass roll angle at body centre of gravity 92

5.20 Sprung mass roll rate at body centre of gravity 92

5.21 Power spectrum plot of displacement response for pitch

mode test 93

5.22 Power spectrum plot of acceleration response for pitch

mode test 93

5.23 Power spectrum plot of displacement response for pitch

mode test 94

5.24 Power spectrum plot of acceleration response for pitch

mode test 94

5.25 Subjective response of the human body to vibration motion 95

5.26 Human reaction to vertical vibration 96


5.28 Sprung mass displacement at body centre of gravity for

different suspension spring stiffness 100

5.29 Sprung mass acceleration at body centre of gravity for


5.30 Sprung mass pitch angle for different suspension spring

stiffness 100

5.31 Sprung mass pitch rate for different suspension spring

stiffness 101

5.32 Sprung mass displacement at body centre of gravity for


5.33 Sprung mass acceleration at body centre of gravity for


xviii

5.34 Sprung mass roll angle at body centre of gravity for different


5.35 Sprung mass roll rate at body centre of gravity comparison

for different suspension spring stiffness 103

5.36 Sprung mass displacement at body centre of gravity

comparison for different passenger loadings 104

5.37 Sprung mass acceleration at body centre of gravity comparison

for different passenger loadings 105

5.38 Sprung mass displacement at body centre of gravity

comparison for different passenger loadings 106

5.39 Sprung mass acceleration at body centre of gravity comparison

for different passenger loadings 106

xix

LIST OF SYMBOLS

Cs - Suspension Damping

Cs f - Suspension Damping (front)

Cs l - Suspension Damping (left)

Cs r - Suspension Damping (rear) – (for pitch mode)

Cs r - Suspension Damping (right) – (for roll mode)

frsC , - Front right suspension damping

flsC , - Front left suspension damping

rrsC , - Rear right suspension damping

rlsC , - Rear left suspension damping

frsF , - Suspension force at front right corner

flsF , - Suspension force at front left corner

rrsF , - Suspension force at rear right corner

rlsF , - Suspension force at rear left corner

frtF , - Tyre force at front right corner

fltF , - Tyre force at front left corner

rrtF , - Tyre force at rear right corner

rltF , - Tyre force at rear left corner

Ic - Pitch Inertia

Ic r - Roll Inertia

xxI - roll axis inertia

yyI - pitch axis inertia

xx

Ks - Suspension Stiffness

Ks f - Suspension Stiffness (front)

Ks l - Suspension Stiffness (left)

Ks r - Suspension Stiffness (rear) – (for pitch mode)

Ks r - Suspension Stiffness (right) – (for roll mode)

frsK , - Front right suspension spring stiffness

flsK , - Front left suspension spring stiffness

rrsK , - Rear right suspension spring stiffness

rlsK , - Rear left suspension spring stiffness

Kt - Tire Stiffness

Kt f - Tyre Stiffness (front)

Kt l - Tyre Stiffness (left)

Kt r - Tyre Stiffness (rear) – (for pitch mode)

Kt r - Tyre Stiffness (right) – (for roll mode)

frtK , - Front right tyre stiffness

fltK , - Front left tyre stiffness

rrtK , - Rear right tyre stiffness

rltK , - Rear left tyre stiffness

fL - Distance between the front and the C.G of sprung mass

rL - Distance between the rear and the C.G of sprung mass

Mc - Sprung Mass

Ms - Sprung Mass (Wheel)

sM - Sprung mass

Mt f - Unsprung Mass (front)

Mt l - Unsprung Mass (left)

Mt r - Unsprung Mass (rear) – (for pitch mode)

Mt r - Unsprung Mass (right) – (for roll mode)

Mu - Unsprung Mass (Load on one wheel)

fruM , - Front right unsprung mass

xxi

fluM , - Front left unsprung mass

rruM , - Rear right unsprung mass

rluM , - Rear left unsprung mass

lW - Distance between the left and the C.G of sprung mass

rW - Distance between the right and the C.G of sprung mass

frgZ , - Front right road/ground displacement

flgZ , - Front left road/ground displacement

rrgZ , - Rear right road/ground displacement

rlgZ , - Rear left road/ground displacement

frsZ , - Front right sprung mass displacement

flsZ , - Front left sprung mass displacement

rrsZ , - Rear right sprung mass displacement

rlsZ , - Rear left sprung mass displacement

fruZ , - Front right unsprung mass displacement

fluZ , - Front left unsprung mass displacement

rruZ , - Rear right unsprung mass displacement

rluZ , - Rear left unsprung mass displacement

frsZ ,& - Front right sprung mass velocity

flsZ ,& - Front left sprung mass velocity

rrsZ ,& - Rear right sprung mass velocity

rlsZ ,& - Rear left sprung mass velocity

fruZ ,& - Front right unsprung mass velocity

fluZ ,& - Front left unsprung mass velocity

rruZ ,& - Rear right unsprung mass velocity

rluZ ,& - Rear left unsprung mass velocity

sZ&& - Sprung mass vertical acceleration at the centre of gravity

xxii

fruZ ,&& - Front right unsprung mass vertical acceleration

fluZ ,&& - Front left unsprung mass vertical acceleration

rruZ ,&& - Rear right unsprung mass vertical acceleration

rluZ ,&& - Rear left unsprung mass vertical acceleration

θ - Pitch angle at body centre of gravity

φ - Roll angle at body centre of gravity

xxiii

LIST OF APPENDICES

APPENDIX TITLE PAGE

A Tramcar Properties 118

B Experiment for locating centre of gravity 121

C Simulation Results 133

D Load Cells Specifications 154

CHAPTER 1

INTRODUCTION

A driver judges his vehicle based on subjective aspects. Vehicle dynamic

characteristics including ride and handling have a major impact on this evaluation.

For this reason, vehicle manufacturers have grown investments in order to improve

this vehicle dynamic behaviour (Persegium et al., 2003). The perceived comfort level

and ride stability of a vehicle are the two of the most important factors in a vehicle’s

subjective evaluation. There are many aspects of a vehicle that influence these two

properties, most importantly the primary suspension components, which isolate the

frame of the vehicle from the axle and the wheel assemblies. In the design of

conventional primary suspension system there is a trade off between the two

quantities of ride comfort and vehicle stability. A suspension may be optimised for

handling performance, or it may be optimised to isolate the occupants from road

disturbances, but it cannot excel at both. In practice, the performance of conventional

vehicle suspensions is a compromise between ride and handling (Kazemi et al., 2000,

and Tener, 2004). If a suspension is designed to optimise the handling and stability

of the vehicle, the passenger often perceives the ride to be rough and uncomfortable.

On the other hand, if the suspension is designed to optimise the comfort level, the

vehicle will be comfortable, but may not be too stable during vehicle manoeuvres.

2

Focusing on the aspect of ride comfort, the quality referred to as "ride

comfort" is affected by a variety of factors, including high frequency vibrations,

body booming, body roll and pitch, as well as the vertical spring action normally

associated with a smooth ride. If the vehicle is noisy, if it rolls excessively in turns,

or lurches and pitches during acceleration and braking, or if the body produces a

booming resonance, the passengers will experience an "uncomfortable ride." The

intention of this study is to perform dynamic analysis on a suspension system,

analysing the relationship between the parameters of the suspension system with the

factors affecting ride comfort that was mentioned above.

While there have been many studies performed on the more advanced

suspension systems, such as the active or semi active suspension, this study will

focus only on the passive suspension system. One of the reasons is that in this study,

the analysis performed is on an existing vehicle that uses a passive suspension

system. Furthermore, even though the use of microprocessors combined with

technologies developments in actuators, adjustable dampers, and variable springs has

led to an upsurge of more advance suspensions such as fully active and semi active

suspensions, vehicles with passive suspension system are still likely to dominate

high volume passenger car production for the foreseeable future (Olatunbosun and

Dunn, 1991).

This study will focus on the suspension system of a non-commercial transport

for recreational purposes designed by the Mechanical Engineering Faculty of

Universiti Teknologi Malaysia (UTM), which is commonly known as ‘tramcar’. The

vibration level the passengers of the tramcar are exposed to would be the focal point.

Other factors affecting ride comfort including body pitch and roll will also be looked

into.

As mentioned above, the tramcar is a non-commercial transport for

recreational purposes. It was designed for the use inside a zoo, airport, around a

hotel, golf resort and multi-level company to fetch customers. The tramcar is a

simple car; it does not have any special technology installed onto it. To achieve its

recreational purpose, tramcar does not have any door and safety belt. It makes it

3

easier for the passenger going up and down the vehicle. The tramcar have eight seats;

two including the driver’s seat in the front row, three in the middle row, and three in

the last row. The tramcar uses Toyota ST 190 MacPherson strut on its both

suspension systems. MacPherson strut is an independent suspension system which is

small and lightweight with very little unsprung mass. It has fewer total components

compared to alternative suspension system and is fairly straight forward to assemble

and repair (Chuan, 2005). Figure 1.1 shows the tramcar viewed from various angles.

(a) (b)

(c) (d)

Figure 1.1: The tramcar as viewed from various angles; (a) the front view of the

tramcar, (b) the rear view of the tramcar, (c) the passenger seating in the tramcar, and

(d) the interior view of the driver’s compartment

4

1.1 Objectives

The objectives of this project are:

i. To determine the acceleration response of the tramcar suspension

ii. To evaluate acceleration response in term of ride comfort level

corresponding to available standards

iii. To suggest possible improvement in the comfort level in term of

modifying the suspension parameters

1.2 Scope of the Project

The scopes of this study are:

i. The study on the tramcar built by UTM.

ii. The study focuses only on passive suspension system.

iii. The study will be evaluating the acceleration response of the tramcar in

analysing the ride comfort level of passenger in the tramcar.

iv. Only ride analysis is performed and the vehicle handling analysis is

neglected.

v. MATLAB Simulink would be used in performing the numerical analysis

on the suspension system.

vi. The ride comfort analysis of the tramcar would be based on available

benchmarks, either from standards such as ISO standards or from

research findings by various researches.

vii. The suggestion for improvement would be by modifying suspension

parameters.

5

1.3 Research Methodology

The research methodology flowchart for this project is shown in Figure 1.2.

The proposed tasks to be performed to achieve the objective of the study and in

compliance with the scope of the study are as outlined below:

Figure 1.2: Research methodology flow-chart

Literature Review

Develop quarter car / half car / full car models

Simulation with MATLAB Simulink using input parameters of Proton Waja experimental test

Model Validation

Model Validated

Model Updating

Numerical Modelling

Validation OK?

Yes

No

Available experimental data from Proton Waja experimental test

Simulation using MATLAB Simulink for

Tramcar

Ride Comfort Analysis

Numerical Analysis

Tramcar Geometry Data

Discussion and Conclusion

6

1.3.1 Literature Review

The purpose of literature review is twofold; to get the theories and

background information as the foundation of the study, and to get to know the past

studies that have been done. The background information is gathered mostly from

text books and reference books. The past studies are reviewed from technical papers.

Internet sources were also reviewed. The standards will also be reviewed as the

benchmark values for the judgement and evaluation to be made later on.

1.3.2 Numerical Modelling

The quarter car, half car, and full car models are going to be developed as the

dynamic models for the numerical analysis. The mathematical model would be

derived for each suspension model. From the mathematical models, numerical

simulation will be performed using MATLAB Simulink. The input parameters would

be the geometry data and the tramcar properties; the body properties, the vehicle

estimated weight, and the suspension properties. The output parameters would be the

displacement and acceleration response.

1.3.3 Model Validation

The model developed would be validated using available experimental results

data obtained from literature. Using the same input parameters as used in the

literature, the numerical simulation was executed using the numerical modal derived.

The results of the output parameters from the simulation would be compared to that

of the literature. The model would be validated given that the simulation results

show a similar profile to that of the available experimental results.

1.3.4 Model Updating

With the experimental output data as reference, this step would be performed

if there is no correlation between the simulation output data and the experimental

output data.

7

1.3.5 Collecting the Geometry Data and Tramcar Properties

The geometry of the tramcar is to be measured directly in the reference

vehicle real structure. It will be carried out using measurement instruments. For other

tramcar properties that need to be determined using experimental techniques, such as

determining the mass or the centre of gravity of the tramcar, the corresponding

experimental testing would be performed.

1.3.6 Numerical Simulation

With the numerical model already validated, it would be used for the

numerical simulation to obtain the output parameters for the tramcar. The input

parameters would be from the tramcar geometry data and properties. The output of

the simulation would be the dynamic response of the suspension system of the

tramcar.

1.3.7 Ride Comfort Evaluation

The output data, namely the acceleration response, will be evaluated in

comparison with available standards in judging whether the comfort level of the

tramcar is within the benchmark comfort level or not. Ride comfort will also be

evaluated by evaluating other output parameters, such as pitch rate and roll rate,

given that the benchmark for those parameters is available.

1.3.8 Suggestion of Improvement

Some suggestions with regard to the suspension parameters will be made in

the effort to increase the comfort level of the tramcar. Numerical simulation will be

performed using the verified numerical model to illustrate the improvement that

would be achieved with the implementation of the suggestions made.

8

1.4 Outline

Chapter 2 presents the literature review of related past studies. A number of

related literatures will be reviewed and discussed. Chapter 3 presents the background

theories relating to vehicle suspension. It discusses on the necessary background

information; related definition and terminologies, suspension classifications and

types, suspension components, ride quality aspects, role of vehicle suspension,

suspension parameters and suspension system modelling and simulation. Chapter 4

presents the modelling and simulation of tramcar performed in this study. The

numerical modelling process will be described, and the simulation analysis on

tramcar suspension system will be presented. Chapter 5 presents the model

validation and comparative study performed in achieving the objectives. The

validation of the models developed in Chapter 4 will described. Comparative studies

including ride quality evaluation with available standards and parametric studies will

be presented. Discussion on the results and findings will also be presented. Finally

chapter 6 summarises and conclude the study and provides recommendations for

future works.

Documents

DYNAMIC ANALYSIS OF TRAMCAR SUSPENSION SYSTEM …eprints.utm.my/id/eprint/9631/1/MuhammadSaifuddinMFKM2006.pdfof avoiding a very low natural frequency assimilated to motion sickness