IMPROVEMENT OF FRONT CAR BUMPER SYSTEM

MUHAMAD FIRDAUS BIN MAHMUD

Report submitted in partial fulfillment of the requirements for the award of the degree of

Bachelor of Mechanical Engineering with Automotive

Faculty of Mechanical Engineering UNIVERSITI MALAYSIA PAHANG

JUNE 2008

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SUPERVISOR’S DECLARATION

We hereby declare that we have checked this project and in our opinion this project is

satisfactory in terms of scope and quality for the award of the degree of Bachelor of

Mechanical Engineering with Automotive/Manufacturing*

Signature

Name of Supervisor: ZAMRI MOHAMED

Position: Lecturer

Date: 10 November 2008

Signature

Name of Panel: AZIZUDDIN BIN ABD AZIZ

Position: Lecturer

Date: 10 November 2008

* Delete any

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DECLARATION

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

summaries which have been duly acknowledged. The report has not been accepted for

any degree and is not concurrently submitted for award of other degree.

Signature

Name: MUHAMAD FIRDAUS BIN MAHMUD

ID Number: MH05049

Date: 10 November 2008

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ACKNOWLEGDEMENT

Firstly I would like to express my deep gratitude to my supervisor, Mr Zamri Bin

Mohamed for his precious guidance, admonition and incessant encouragement to me in

the way to completing this project. I appreciate and utilize all his advice and supervision

that contribute to finishing this project.

I would also like to wish my special thanks to beloved Faculty of Mechanical

Engineering for giving me permission to borrow and use the Proton Pesona in the

Mechanical Laboratory as my guidance model in designing the front car bumper.

Last but not least, my sincere gratitude to my entire friend in my section group of

M13 and M12 that always give me a support and help to overcome my problem and

difficulties contribute to completing this project.

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ABSTRACT

Designing the bumper with the focus on an improvement aspect is very

important in the automotive industry. The goals are to increase the performance of the

bumper and also to find the solution to reduce the cost of the bumper hence able to

reduce the production cost. The costs of the bumper is high because of the amount of

material used and it also involves many processes including making the grille at the

center of bumper. The new design considers on reducing the amount of material use and

also eliminating the process involve in manufacture the bumper for example eliminating

the grille attachment. The new design also must improve the ability to absorb more

impact load and increase the protection of the front car component. This project

intention is to design an improved of front car bumper and to find the solution for the

problem of high cost and the replacing cost for the front bumper and lastly emphasizing

the cost reducing aspect. The method have been employed was study the front bumper

system, design and analyze the alternative front bumper using CAD software. The

suitable material that can be used as the bumper in terms of economical but still

maintaining the toughness is Plastic-Polycarbonate (Molded) which is not expensive

compare to the best material from the analysis E-Glass Fiber, Plastic-Nylon Type 6/6

and Plastic ABS (Molded). The suitable material to be use for making beam is AISI E

52100 Steel. Rearrangement of the mounting positions gives a different effect on the

ability to withstand the impact force. Additional plate in the improvement design proved

increasing the toughness of the beam.

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ABSTRAK

Merekabentuk bumper dengan member focus kepada aspek pembaikan adalah

sangat penting didalam industri automotif dalam usaha untuk meningkatkan prestasi

bumper dan juga untuk mencari penyelesaian untuk mengurangkan kos bumper dengan

itu mampu mengurangkan kos produksi. Kos bumper adalah tinggi kerana jumlah bahan

yang digunakan dan juga bilangan proses yang terlibat adalah banyak termasuk proses

membuat grille pada bahagian tengah bumper. Rekabentuk baru mempertimbangkan

tentang pengurangan bahan yang digunakan dan juga mengurangkan proses yang terlibat

dalam menghasilkan bumper sebagai contoh menghapuskan proses pemasangan grille.

Namun rekabentuk bumper yang baru juga perlu bertambah baik dalam keupayaan untuk

menyerap lebih banyak daya hentaman, meningkatkan pertahanan komponen hadapan

kereta. Tujuan projek ini adalah untuk merekabentuk bumper kereta yang

dipertingkatkan kualitinya dan untuk mencari penyelesaian bagi masalah harga bumper

dan harga menukarganti bumper yang mahal dan akhir sekali menekankan aspek

pengurangan kos. Kaedah yang digunakan ialah melakukan pengkajian terhadap system

bumper kereta, merekabentuk dan menganalisis rekabentuk bumper alternatif dengan

menggunakan perisian CAD. Bahan yang sesuai untuk digunakan dalam pembuatan

bumper dari aspek ekonomikal tetapi tetap mengekalkan kekuatannya ialah Plastic-

Polycarbonate (Molded) yang kurang mahal dibandingkan dengan material terbaik

daripada analisis E-Glass Fiber, Plastic-Nylon Type 6/6 and Plastic ABS (Molded).

Bahan yang sesuai untuk dibuat ‘beam’ ialah AISI E 52100 Steel. Penyusunan semula

posisi pemasangan member kesan yang berbeza pada keupayaan bumper untuk

menampung daya impak. Penambahan plat didalam rekabentuk yang diperbaharui

terbukti meningkatkan kekuatan pada ‘beam’.

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TABLE OF CONTENTS

Page

TITLE PAGE i

SUPERVISOR DECLARATION ii

DECLARATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES x

LIST OF FIGURES xi

LIST OF GRAPH xiii

LIST OF SYMBOLS xiv

LIST OF ABBREVIATIONS XV

LIST OF APPENDICES xvi

CHAPTER 1 INTRODUCTION 1

1.1 Introduction 1

1.2 Problem Statement 2

1.3 Objectives 2

1.4 Limitation 4

CHAPTER 2 LITERATURE REVIEW 5

2.1 Introduction 5

2.2 Front Bumper System 5

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2.3 Bumper Hydraulic Absorbing System 8

2.4 Underride and Override 9

2.5 Bumper Material Selection 10

2.6 Importance of Bumper 11

2.7 Attribute of a Good Bumper System 11

2.8 Bumper Do Not Bump 12

2.9 Bumper Beam 12

2.10 Impact Time 14

CHAPTER 3 METHODOLOGY 16

3.1 Introduction 16

3.1.1 Literature review 16 3.1.2 Benchmarking Activity 16

3.2 Designing Process 18

3.3 Improvement on Fascia Bumper 21

3.4 Improvement on Beam 22

3.5 Analysis the Design in ALGOR 23

3.6 Flow Chart for Project Methodology 25

CHAPTER 4 RESULTS AND DISCUSSION 27

4.1 Introduction 27

4.2 Impact Force Equation 28

4.3 Bill Of Material 30

4.4 Analysis 30

4.5 Result Analysis for Fascia 32

4.6 Result Analysis for Beam 38

CHAPTER 5 CONCLUSION AND RECOMMENDATION 43

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5.1 Conclusion 43

5.2 Further Study Recommendation 44

REFERENCES 45

APPENDICES A – B4 46-50

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LIST OF TABLES

Figure No. Page 3.1 Bumper and beam dimension 17 4.1 Bill of Material 30 4.2 Bumper Analysis Result 32 4.3 Attachment Analysis Result 35 4.4 Beam Analysis Result 39 4.5 Beam design analysis result 41

xi

LIST OF FIGURES

Figure No. Page 2.1 General component and arrangement of front bumper system 6 2.2 Attachments of foam material 7 2.3 An illustration of bracket attachment 8 2.4 The schematic diagram of hydraulic bumper system 9 2.5 Example of under ride crash damage 10 2.6 A bumper reinforcement bar, shown without the plastic bumper cover 11 2.7 The example bumper beam structure 13 3.1 Front view of Proton Pesona front bumper 17 3.2 Initial design of front bumper 19 3.3 Creating the headlight space 19 3.4 Final design with grille space 19 3.5 Top, front, side and isometric view 20 3.6 Original beam design 20 3.7 Beam design with additional plate 21 3.8 The ordinary and the improved bumper design 22 3.9 The ordinary and the improved beam design 22 3.10 Bumper boundary condition in ALGOR 24 3.11 Beam boundary condition in ALGOR 24 4.1 Load applied in ALGOR analysis for fascia and beam 31 4.2 Displacement magnitude of E-Glass Fiber 33

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4.3 Stress Concentration of E-Glass Fiber 34 4.4 Displacement magnitude of Plastic-LDPE 34 4.5 Stress Concentration of Plastic-LDPE 35 4.6 Manipulation of attachment position (screw mounting) 36 4.7 The toughness mounting position 37 4.8 The best mounting position in terms of reducing screw 38 4.9 Beam Design A (original design) 38 4.10 Displacement magnitude of steel 40 4.11 Displacement magnitude of Aluminium 40 4.12 Design A 41 4.13 Design B 41 4.14 Comparison in displacement magnitude 41 4.15 Comparison in stress concentration 42

xiii

LIST OF GRAPH

Graph No. Page 2.1 Barrier Impact Test Result 15 4.1 Impact Time 29

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LIST OF SYMBOLS

∑ Summation ∫ Integration ∆t Time interval

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LIST OF ABBREVIATIONS

CD Coefficient of Drag FEA Finite Element Analysis GM Glass Mat Thermoplastic 2D Two Dimensions 3D Three Dimensions CAE Computational Aided Engineering ABS Acrylonitrile Butadiene Styrene HDPE High Density Polyethylene LDPE Low Density Polyethylene FEP Fluorinated Ethylene Propylene

AISI American Iron and Steel Institute

LIST OF APPENDIX

xvi

APPENDIX TITLE PAGE Appendix A Gantt Chart 46

Appendix B1 Bumper Design 47

Appendix B2 Bumper Design 48

Appendix B3 Beam Design A 49

Appendix B4 Beam Design B 50

CHAPTER 1

INTRODUCTION

1.1 Introduction

Bumper has been an important feature in protecting the vehicle from serious

damage to the car component in a low speed collision. Especially when the collision

causing damage to the expensive-to-repair part like fender, hood and intercooler.

Bumper is also involves in improving the performance of the car. Bumper size and the

aerodynamic feature of the bumper are the important aspects in lowering the coefficient

of drag, CD. The efficient bumper design will also increase the down force of the car

when it accelerates to give more grips to the tire and the road. This will give a good

handling to the driver ever in high speed driving.

The car bumper is designed to prevent or reduce physical damage to the front

and rear ends of passenger motor vehicles in low-speed collisions. Automobile bumpers

are not typically designed to be structural components that would significantly

contribute to vehicle crashworthiness or occupant protection during front or rear

collisions. It is not a safety feature intended to prevent or mitigate injury severity to occupants

in the passenger cars. Bumpers are designed to protect the hood, trunk, grille, fuel, exhaust

and cooling system as well as safety related equipment such as parking lights,

headlamps and taillights in low speed collisions.

2

Bumpers beam are made of heavy sheet metal and are mounted on the front and

rear of the car. Bumpers are bent and formed into specific shapes in order to absorb and

deliver momentum during a collision. In the event of a collision, the bumper absorbs

some of the impact, which decreases damage to the car and its occupants. It also protects

the front of the car by diverting all of the car's momentum to the object with which it has

collided. The bumper beam is mounted to the car's chassis with special impact absorbers.

These shock absorbers are often spring loaded. In slow speed collisions, this allows the

bumper to compress, and then extend back to its original position. All bumpers are

designed to absorb the energy of the impact. They do this through a series of valves and

air chambers. Some car bumpers have hydraulic chambers. In the event of a collision,

the absorption unit allows air and/or hydraulic fluid to pass through small openings.

Forcing the air/fluid through the valve openings absorbs the energy from the collision.

The bumper's job is to minimize damage, primarily to the occupants of the vehicle and

to the vehicle itself.

1.2 Problem Statement

Nowadays the part cost for front bumper is still high and the cost for replacing is

quite expensive especially if surrounding area or part also damaged. Many part that

make up a bumper system, involving a lot of material and processes there for the

manufacturer difficult to reduce the price. Customer also blame to the manufacture that

the bumper easily to damage although the collision was slow. The material of the

bumper should be analyzed to find the alternative material that can improve the

toughness.

1.3 Objective

The main objectives of this project is first to study the front bumper properties

and the sample of the car was the Proton Pesona. The bumper design of the Proton

Pesona has been benchmarked to determine the real dimension of the bumper. Second

objective is to design the generic front bumper using Solidwork software including the

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improvement that suitable to be made increase the performance of the bumper. The

designs then were analyzed using Finite Element Analysis method (FEA) to study the

toughness of the bumper design by performing the impact test. The aim of this process is

to determine the strength of the front bumper, identify the segment or part that the crack

will occur or where the concentration of stress is high when force is attached in front of

the bumper. This is to ensure that the designed bumper is functioning properly in absorb

the impact energy and protecting the front car component. The third objective is to

emphasize the improvement and cost reduction aspect of the designed bumper including

the beam design.

This project will focus on designing a improvement front bumper that meets all

the regulation aspect. In this research the consideration of improving the front car

bumper will be the most important things. To achieve the objective of the project, the

following research activities are performed:

1. Literature review, collecting and gathering the information about front bumper.

2. Benchmark the current front car bumper design (Proton Pesona)

3. Make a comparison between the current design and the alternative design.

4. Perform CAE simulation to the alternative bumper.

In the end of this project, the expected outcome is all the problem stated above

can be solve, the part cost of the front bumper and the cost for repairing can be reduce.

Reducing the parts that make up the bumper system, there for reducing the price is

possible. The suitable material for the fascia and the beam will be determined so that the

improvement designs have the toughness and increase in ability to withstand the impact

force. The alternative design predicated to give a good protection to the front car

component when low speed collision happened and work properly in absorb the energy

of the impact. Also it should be easy to assemble and attached (installation).

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1.4 Limitations

The limitation for this project is hard to find the journal and book about design

the low cost front bumper in the Knowledge Management Centre (KMC) of University

Malaysia Pahang. The whole literature review journals are searched in internet.

CHAPTER 2

LITERATURE REVIEW

2.1 Introduction

This chapter will provide detail description of literature review done according to

the project title of front car bumper system. A bumper is a car shield made of steel,

aluminium, rubber, or plastic that is mounted on the front and rear of a passenger car.

When a low speed collision occurs, the bumper system absorbs the shock to prevent or

reduce damage to the car. Some bumpers use energy absorbers or brackets and others are

made with a foam cushioning material. The car bumper is designed to prevent or reduce

physical damage to the front and rear ends of passenger motor vehicles in low-speed

collisions. Automobile bumpers are not typically designed to be structural components

that would significantly contribute to vehicle crashworthiness or occupant protection

during front or rear collisions. It is not a safety feature intended to prevent or mitigate

injury severity to occupants in the passenger cars. Bumpers are designed to protect the

hood, trunk, grille, fuel, exhaust and cooling system as well as safety related equipment

such as parking lights, headlamps and taillights in low speed collisions (Status Report,

Vol 4, No 2, IIHS, 2007).

2.2 Front Bumper System

Generally, a bumper is attached to either end of a vehicle to absorb impact in a

collision, thereby protecting passenger. As shown in figure 1, a conventional bumper

system comprises a bumper cover 1 defining an outer appearance of the bumper system,

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an energy absorber 2 formed of an elastic material such a polypropylene foam body or

an urethane foam body to absorb energy, an impact beam for supporting the energy

absorber 2, and a stay 4 for connecting the impact beam 3 to a vehicle body (Won-Jun

Choi, 2003).

Figure 2.1: General component and arrangement of front bumper system

Source: Won-Jun Choi 2003

The impact beam has previously been formed of a steel material having a closed

or “C” shaped section. However, in recent years, to meet with a tendency toward more

lightweight and compact vehicles, impact beam formed of a variety of material have

been developed. Particularly as proven that an impact beam formed of a glass mat

thermoplastic (GMT) thought a compression molding process in superior to other

materials, it is widely employed to vehicle for export. However, the conventional GMT-

made impact beam as shown in figure 2, formed to be thick thought its overall body to

provide a necessary rigidity and strength. Therefore the space saving and weight

reducing effect is not so remarkable when compared with the steel beam. In addition,

when tips are formed on an upper or lower end of the beam to improve the performance,

the bumper cover and the energy absorber may be damage by the tips in the case where

the mounting space is not sufficient. Furthermore although a reinforcing sheet has been

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applied to several conventional beams, since there is a need for an additional process for

forming the reinforcing sheet, the manufacturing cost are increased (Won-Jun Choi,

2003).

Figure 2.2: Attachments of foam material

Source: Won-Jun Choi 2003

Meanwhile, the energy absorber 2 is disposed between the bumper cover 1 and

the impact beam 3 to absorb impact energy. When the energy absorber 2 is subject to an

impact greater than its critical elastic force, it crack and must therefore be replaced.

However in the conventional bumper system, since the energy absorber is integrally

formed, the whole bumper system must be replaced, increasing the repairing costs

(Won-Jun Choi, 2003).

An energy absorption and management system for a motor vehicle includes a

bumper interconnected to the vehicle frame through a pair of substantially identical

energy absorbing assemblies or bumper bracket. Each assembly includes an outer

portion and an inner portion. The outer portion has a pair of spaced apart sides which are

interconnected through an actuate segment. The inner portion preferably stepped in a

longitudinally extending direction such that they include first and second substantially

8

horizontal segment which are vertical spaced from one another. If the motor vehicle is

involved in a frontal impact of a predetermined speed, energy is absorbed and managed

though deformation of the outer and inner portions. Deformation of the outer portion is

controlled by the inner portion which is welded or otherwise fixedly attached thereto at

spaced apart points (Ronald S. Kemp, Oxford Nov. 16, 1999).

Figure 2.3: An illustration of bracket attachment

Source: Ronald S. Kemp 1999

2.3 Bumper Hydraulic Absorbing System

A shock-absorbing bumper system for an automotive vehicle includes a conduit

subsystem for conducting hydraulic fluid therein, a supply subsystem for supplying

hydraulic fluid, a pressure balancing subsystem for regulating the pressure of hydraulic

fluid, front and rear bumper subsystem for respectively extending and retracting front

and rear bumper and for absorbing shock, a switching subsystem for directing hydraulic

fluid, and feedback subsystem for absorbing shock (Yang Chin-Hun, Jun 1991).