DESIGN AND FABRICATION OF A

REDUCED SCALE TIRE TEST MACHINE

KONG WEI SHEN

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

SUPERVISOR DECLARATION

“I hereby declare that I have read this thesis and in my opinion this report is

sufficient in terms of scope and quality for the award of the degree of

Bachelor of Mechanical Engineering (Automotive)”

Signature: ………………………..

Supervisor: ………………………..

Date: ………………………..

DESIGN AND FABRICATION OF A

REDUCED SCALE TIRE TEST MACHINE

KONG WEI SHEN

This report is submitted in partial

fulfillment of the requirements for the award of a

Bachelor of Mechanical Engineering (Automotive)

Faculty of Mechanical Engineeing

Universiti Teknikal Malaysia Melaka

JUNE 2013

ii

DECLARATION

“I hereby declare that the work in this report is my own except for summaries and

quotations which have been duly acknowledged.”

Signature: ……………………….

Author: ……………………….

Date: ……………………….

iii

CATION

Gratitude to PSM supervisor

PSM panel

Family and

Course mates

iv

ACKNOWLEDGEMENT

I would like to express my appreciation to all folks who’s provided me

support and guidance to complete this report. First and foremost, gratitude to my

PSM supervisor, Mr. Amrik Singh who had given me technical advice, suggestion

and encouragement to complete this project. Besides, I would like to acknowledge

with much appreciation to suppliers who provided fabrication guidance and

electronics component circuit connection. Furthermore deepest appreciation upon my

parents and my course-mate who given me financial aid and encouragement.

Certainty, appreciation upon my university, faculty staff and technician who

had provided all kind of information, resources and aids to given an arm to me in

completing this report. Last but not least, I would gratitude to PSM panels that spend

their golden time to evaluate my project and reports. Thank you.

v

ABSTRAK

Ia adalah penting untuk mengkaji daya maju oleh tayar untuk memahami

reaksi dinamik kenderaan yang menggambarkan pelbagai peristiwa-peristiwa yang

berlaku dalam keadaan memandu yang sebenar. Penjanaan kuasa-kuasa tayar

berdasarkan nisbah slip membujur dan tayar slip sudut input dikaji. Selain itu, skala

penuh ujian peralatan tayar dan kelebihan mesin skala Kurangkan telah dikaji. Projek

ini memberi tumpuan kepada pembangunan mesin ujian tayar yang berskala rendah

yang dapat menentukan kekukuhan tayar membujur dan ketegangan memborong

daripada satu kepada skala kelima kenderaan kawalan jauh. Untuk membangunkan

mesin ini, pelbagai reka bentuk konsep telah dijana dan reka bentuk yang paling

sesuai dipilih dengan menggunakan keputusan berat badan kaedah matriks.

Berdasarkan reka bentuk yang dipilih, reka bentuk terperinci termasuk bil komponen

mekanikal dan bil komponen elektrik yang menentukan fungsi tertentu setiap

komponen untuk menjalankan fungsi yang ditetapkan. Mesin ujian tayar berskala

rendah membina dari mekanisme mudah yang menggunakan motor DC untuk

merangsang gendang berputar tayar di kedudukan pegun, pengekod sudut untuk

mengukur kelajuan putaran tayar, motor pelangkah untuk menyediakan roda

mengemudi sudut, Prony brek digunakan untuk mendapatkan tindak balas dijana

oleh tayar pada tolok membujur dan tekanan yang digunakan untuk mengukur arah

sisi. Analisis tekanan dilakukan pada kerangka struktur mesin untuk mengelakkan

kegagalan struktur. Model tayar Dugoff dibangunkan untuk menyediakan maklumat

mengenai ketegangan membujur dan ketegangan memborong tayar. Ujian berfungsi

adalah penting untuk memastikan mesin ujian tayar boleh berfungsi dengan baik dan

dapat menentukan tayar ketegangan dan ketegangan memborong yang membolehkan

penyelidik dan jurutera untuk menyiasat mengurangkan ciri-ciri tayar.

vi

ABSTRACT

It is important to study forces developed by the tire to understand the dynamic

behavior of the vehicle which reflect multiple events that occur under real driving

condition. The generation of these tire forces based on the longitudinal slip ratio and

tire slip angle input is studied. Besides, the full scale tire test apparatus and the

advantages of reduce scale machine is studied. This project is focus on development

of a reduce scale tire test machine which able to determine the tire longitudinal

stiffness and cornering stiffness of a one to fifth scale remote control vehicle. To

develop this machine, multiple conceptual designs have generated and the most

appropriate design is selected by using weight decision matrix method. Based on the

selected design, detail design included bill of mechanical component and bill of

electrical component which determined the specific function of every component to

carry out specifies task. Reduce scale tire test machine build up from simple

mechanism which used a DC motor to stimulate a drum to rotate the tire in stationary

position, angular encoder to measure tire rotational speed, a stepper motor to provide

wheel steer angle, prony brake used to obtain reaction force generate by tire at

longitudinal and strain gauge used to measure lateral direction. Stress analysis is

done on the machine structural frame to avoid structural failure. Dugoff tire model is

developed to provide tire longitudinal and cornering stiffness information. Functional

test is important to ensure tire test machine can work properly and able to determine

the tire longitudinal and cornering stiffness which enable the researchers and

engineer to investigate reduce scaled tire characteristic

vii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRAK v

ABSTRACT vi

TABLE OF CONTENTS vii

LIST OF TABLES x

LIST OF FIGURES xi

LIST OF SYMBOLS xiv

LIST OF APPENDICS xv

LIST OF ABBREVIATIONS xvi

CHAPTER I INTRODUCTION 1

1.1 Overview 1

1.2 Problem Statement 2

1.3 Objective 2

1.4 Scope 2

1.5 Organization of Report 3

CHAPTER II LITERATURE REVIEW 4

2.1 Tire Forces 4

2.1.1 Longitudinal Tire Force With Slip Ratio 5

2.1.2 Lateral Tire Forces 6

2.2 Scaled Model Testing Apparatus 7

viii

CHAPTER TITLE PAGE

2.3 Full Scale Dynamic Tire Forces Measuring Device 10

2.4 Advantages Using Reduced Scale Machine 11

2.5 Engineering Design 12

2.5.1 Defining The Problem 12

2.5.2 Gathering Information 12

2.5.3 Generating Multiple Solutions 13

2.5.4 Analyzing And Selecting Solution 13

2.5.5 Test And Implemention Solution 14

2.6 Evaluating Design 14

2.6.1 Comparison Based On Absolute Criteria 14

2.6.2 Pugh Concept Selection Method 14

2.6.3 Weighted Decision Matrix 15

2.7 Prony Brake 16

CHAPTER III METHODOLOGY 18

3.1 Project Flow Chart 18

3.1.1 Overview of Project 19

3.2 Conceptual Design 19

3.2.1 Generation of Conceptual Design 20

3.2.2 Conceptual Design 1 22

3.2.3 Conceptual Design 2 23

3.2.4 Conceptual Design 3 23

3.3 Design Evaluation And Selection 24

3.3.1 Weighted Decision Matrix 24

3.4 Detail Design 28

3.4.1 Bill of Mechanical Components 29

3.4.2 Bill of Electronic Component 29

3.4.3 Schematic Diagram of Machine Circuit 29

3.4.4 Programming 30

3.5 Stress Analysis 31

3.5.1 Finite Element Analysis 31

3.6 Fabrication 36

ix

3.7 Mechanism 37

3.7.1 Mechanism of Longitudinal Stiffness 37

3.7.2 Mechanism of Cornering Stiffness 38

3.8 Functional Test 38

3.8.1 Tire Longitudinal Stiffness Test 38

3.8.2 Tire Cornering Stiffness Test 41

3.9 Study The Effect of Tire Model Input 42

3.9.1 Formula for Dugoff tire model 42

CHAPTER IV RESUTLS AND DISCUSSION 44

4.1 Results of FEM 44

4.2 Results of Dugoff Tire Model 45

4.3 Fabrication Constrain 49

CHAPTER V CONCLUSION AND RECOMMENDATION 51

5.1 Conclusion 51

5.2 Recommendation 52

REFERENCES 53

APPENDICES 55

x

LIST OF TABLES

NO TITLE PAGE

2.1 Pugh Method Selection 15

2.2 Weighted Decision Matrix 16

3.1 Product requirement 20

3.2 Morphology Chart for Reduced Scale Tire Test Machine 21

3.3 Criterion-easy of fabrication 25

3.4 Criterion-cost of material 26

3.5 Criterion-easy of assembly 26

3.6 Criterion-longitudinal force measuring method 27

3.7 Criterion-rotational speed measuring method 27

3.8 Criterion-lateral force measuring method 27

3.9 Weight decision matrix 28

3.10 Structural Properties of Aluminum 6061-T6 31

3.11 List of labeled part 37

xi

LIST OF FIGURES

NO TITLE PAGE

2.1 Tire forces in three axes

(Source: Rajamani, 2012) 4

2.2 Diagram illustrates longitudinal velocity and rotational

velocity of tire

(Source: Rajamani, 2012) 5

2.3 Slip angle and lateral force

(Source: Rajamani, 2012) 6

2.4 Cornering stiffness testing apparatus

(Source: Brien et al., 2004)

8

2.5 Cornering stiffness measuring device

(Source: Wannasuphoprasit et al., 2009) 9

2.6 Scale tire testing configuration diagram

(Longoria et al., 2004)

10

2.7 Dynamic tire force measuring device

(Source: Pirjola, 2009) 11

2.8 Prony brake 17

3.1 Flow chart for design and fabrication of reduced scale tire

test machine

18

3.2 Conceptual design-1 22

3.3 Conceptual design-2 23

3.4 Conceptual design-3 24

xii

NO TITLE PAGE

3.5 Schematic diagram of actuator 30

3.6 Connection between computer, arduino annd encorder 30

3.7 Engineering properties of Aluminum 6061-T6 32

3.8 Static analysis of machine structural frame 32

3.9 Define the support or the restrain 33

3.10 Define the load/moment 33

3.11 Define the tetrahedron mesh size 34

3.12 Define the tetrahedron mesh node 34

3.13 Define the tetrahedron mesh suppression 35

3.14 Computation status 35

3.15 Mesh node and element display 36

3.16 Reduce scale tire test machine 36

3.17 Tire locked by nut 39

3.18 Encorder connected to arduino 39

3.19 Arduino monitor 39

3.20 Gap betweeen tire and drum 39

3.21 Weighing machine is set zero 40

3.22 Force from prony brake 40

3.23 Munual controller of DC motor 40

3.24 Arduino monitor 41

3.25 Tire is steer into an angle 41

3.26 Vertical axle and lock it by nut 41

3.27 Matlab Simulink of Dugoff tire model 42

3.28 Detailed Matlab SIMULINK model 43

4.1 The analysis shows the result by display deformation. 44

4.2 Analysis shows the result by display Von Misses Stress

Distribution 45

4.3 Graph of longitudinal force against slip angle with different slip

ratio 46

xiii

NO TITLE PAGE

4.4 Graph of longitudinal force against longitudinal slip with

different vertical force 46

4.5 Graph of longitudinal force against slip angle with different tire

vertical force 47

4.6 Graph of longitudinal force against longitudinal slip with

different slip angle 47

4.7 Graph of lateral force against slip angle with different slip ratio 48

4.8 Graph of lateral force against slip angle with different vertical

force 48

4.9 Graph of lateral force against slip ratio with different slip angle 49

4.10 Graph of lateral force against slip angle with different vertical

force 49

xiv

LIST OF SYMBOLS

y =

Tire slip angle

x = Tire longitudinal slip

xV = Longitudinal velocity of wheel, sm /

= Angular velocity of wheel, srad /

= Rotational velocity of the wheel

= Tire slip angle, rad

= Steering Angle, rad

= Coefficient of friction of tire

xF = Longitudinal tire force, N

yF = Lateral tire force, N

zF = Tire vertical force, N

T = Torque, Nm

W = Weight, g

R = Radius, cm

xv

LIST OF APPENDICES

NO TITLE PAGE

A Gantt Chart fot PSM 1 59

Gantt Chart fot PSM 2 59

B Conceptual Design-1 60

Conceptual Design-2 60

Conceptual Design-3 61

C Isometric Drawing of Reduced Scale Tire Test Machine 62

Structural Frame 62

Drum 63

Fixer 63

Moveable Plate 64

Prony Brake 64

Shaft 65

Support Bar 65

Vertical Axle 66

Moveable Top Plate 66

Moveable Side Plate 67

Frame-Sub Part 1 67

Frame-Sub Part 2 68

Frame-Sub Part 3 68

Frame-Sub Part 4 69

Frame-Sub Part 5 69

xvi

LIST OF ABBREVIATIONS

CAD Computer Aided Drawing

CATIA Computer Aided Three-dimensional Interactive Application

DC Direct Current

FEA Finite Element Analysis

FEM Finite Element Method

PSM Project Sarjana Muda

CHAPTER I

INTRODUCTION

1.1 OVERVIEW

Tire is important to support vertical load while cushioning road shocks,

developed longitudinal force for acceleration and braking, develop lateral forces for

cornering (Gillespie, 1992). Development of reduced scale tire test machine is

essential to determine the tire longitudinal stiffness and cornering stiffness of a

reduce scale remote control vehicle. This reduced scale machine focus to determine

tire parameter of a one to fifth reduced scale remote control vehicle. These properties

of tire are important in tire research and improvement especially in developing a

brake caliper and brake pad of a reduced scale vehicle. Reduced scale machine is

developed since parameter of a reduced scale tire is similar to the actual scale tire

vehicle.

Reduced scale tire test machine build up from simple mechanism to obtain

longitudinal force, lateral force, tire rotational speed, tire relative longitudinal speed,

wheel steer angle. Design of tire test machine consists of drum to rotate the tire in

stationary position, angular encoder to measure tire rotational speed, a stepper motor

to provide wheel steer angle, force sensor to obtain reaction force generate by tire at

longitudinal and lateral direction.

2

1.2 PROBLEM STATEMENT

It is important to study tire forces on developed by the tire because the

dynamic behavior of the vehicle depends on these forces especially when the vehicle

is driven to its limit. By combining these parameters, it is possible to understand

multiple events that occur under real driving condition. Therefore, the assumption

that tire has linear behavior especially in longitudinal and lateral direction is not true

since during extensive steering and throttle or braking inputs by the driver, the tires

operates in non-linear region. Besides, for vehicle model simulation purpose,

accurate tire parameters are required. In this project, a low cost reduced scale tire test

machine will be developed to evaluate the longitudinal and lateral tire behavior. The

generation of these tire forces based on the tire longitudinal slip, tire slip angle input

and tire vertical force will be studied. The tire parameters determined using this

machine could be used for simulation of reduced scale vehicles.

1.3 OBJECTIVE

1. To design and fabricate a reduced scale tire test machine which able to obtain

one to fifth reduced scale tire parameter.

2. To perform stress analysis on the structure of the tire test machine.

1.4 SCOPE

1. Conduct literature study on the fundamentals of tire longitudinal and

cornering stiffness.

2. Design a reduced scale tire test machine using CAD software.

3. Conduct stress analysis using CAE software.

4. Conduct fabrication to the tire test machine.

3

1.5 ORGANIZATION OF REPORT

The remaining sections in this report are presented in five chapters.

Chapter II:

This chapter included all study about tire, development of tire forces, previous

development of scale model testing apparatus, full scale dynamics tire measuring

device, advantages of reduce scale machine and theory of engineering design.

Chapter III:

This chapter discusses methodology used in this project by review generation of

concept design, appropriate selection method for design evaluation and review of

electronic components for machine installation. This chapter also explains all detail

design by configure bill of mechanical components, bill of electronic component and

identify suitable electric circuit and programming for the machine. Besides, this

session also included stress analysis and development of Dugoff tire model for

validation and explains the reduce scale tire test machine to carry out test to

determine tire longitudinal stiffness and cornering stiffness.

Chapter IV:

This chapter review all the fabrication work had been done and all problems

encounter during the machine development.

Chapter V:

This chapter summarizes important issue throughout the entire project and declares

the function of the machine with recommendation for future work.

CHAPTER II

LITERATURE REVIEW

2.1 TIRE FORCES

Tire test machine is greatly related to development of tire forces and it

behavior. The vehicle tire forces and moments from the road act on each tire

contribute to the behavior of the tire. The tire receives force from the road is assumed

to be at the center of the contact patch and can be decomposed along the three axes.

The three axes is X- axis, Y-axis and Z-Axis. X-Axis due to longitudinal force

caused by vehicle longitudinal movement. Y-Axis due to the lateral force cause

by cornering effect and the force along the Z- axis due to vertical force due to the

vertical load support by the tire. Figure 2.1 shows the tire forces in three axes.

Figure 2.1: Tire forces in three axes

(Source: Rajamani, 2012)

5

2.1.1 Longitudinal Tire Force with Slip Ratio

Longitudinal tire force generated by tire depends on the slip ratio, the friction

coefficient of the road surface and the normal force on the tire. If the friction

coefficient of the tire-road interface is assumed to be 1 and the normal force is

assumed to be a constant, longitudinal tire force is directly proportional to the

slip ratio. Therefore the longitudinal tire force be modeled as

xx CF (1)

where C = longitudinal stiffness and x = longitudinal slip. Longitudinal stiffness

is a constant property of the wheel and the equivalent rotational velocity of the wheel

as shown in Figure 2.2. This means, longitudinal slip is equal to reffw-Vx. Slip ratio

is equal to the difference between the longitudinal velocity at the axle of the wheel

and the equivalent rotational velocity of the wheel, over maximum value. For

braking, the maximum value is longitudinal velocity. Slip ratio for acceleration have

the rotational velocity of wheel as the denominator (Longoria et al., 2004)

Slip ratio during braking:

x

xWeff

xV

Vr

(2)

Slip ratio during acceleration:

Weff

xWeff

xr

Vr

(3)

Figure 2.2: Diagram illustrates longitudinal velocity and rotational velocity of tire

(Source: Rajamani, 2012)

6

2.1.2 Lateral Tire Forces

The lateral force on a tire is proportional to the slip angle at the tire.

Therefore lateral force can be modeled as

)( vy CF (4)

where C = cornering stiffness, = steer angle, v = tire velocity angle and v =

the slip angle of a tire is the angle between the orientation of the tire and the

orientation of the velocity vector of the wheel as shown in Figure 2.3. When a

vehicle is traveling straight and not being steered, the velocity angle at the tire

and the steering angle are both zero, resulting in zero slip angle. Obviously, the

lateral tire force is proportional to slip angle. In the static region of the contact patch,

the tip of each tread is in contact with the ground and remains stationary. The top of

the tread therefore moves with respect to the tip of the tread resulting in tread

deformation. The magnitude of lateral deflection of the tread is proportional both to

the lateral velocity and to the magnitude of time spent by the tread in the contact

patch. Since the lateral velocity is proportional to velocity and slip angle while the

amount of time in the contact patch is inversely proportional to the rotational velocity,

the lateral tread deflection is effectively proportional only to the slip angle. The

lateral force on the tire based on the magnitude of lateral deflection of the

treads in the contact patch. Hence, the lateral force is proportional to slip angle (Ertas

et al., 1996)

Figure 2.3: Slip angle and lateral force

(Source: Rajamani, 2012)