IMPROVEMENT OF REAR BUMPER DESIGN

MOHD HAFIZAN BIN MAMAT

UNIVERSITI MALAYSIA PAHANG

IMPROVEMENT OF REAR BUMPER DESIGN

MOHD HAFIZAN BIN MAMAT

A report submitted in partial fulfillment of the requirements

for the award of the degree of

Bachelor of Mechanical Engineering with Automotive Engineering

Faculty of Mechanical Engineering

UNIVERSITI MALAYSIA PAHANG

NOVEMBER 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 Engineering.

Signature

Name of Supervisor: MR. ZAMRI BIN MOHAMED

Position: LECTURER

Date: 7 NOVEMBER 2008

Signature

Name of Panel: MR. AZIZUDDIN BIN ABD AZIZ

Position: LECTURER

Date: 7 NOVEMBER 2008

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STUDENT’S DECLARATION

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

summaries which have been duly acknowledged. The thesis has not been accepted

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

Signature

Name: MOHD HAFIZAN BIN MAMAT

ID Number: MH05044

Date: 7 NOVEMBER 2008

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My beloved father, Mr. Mamat Bin Taib,

My loving mother Mrs. Khafiah Binti Yusof,

Brothers and sisters,

All my friends

May Allah bless all of you

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ACKNOWLEDGEMENT

Alhamdulillah,

I would like to take this opportunity to express my sincere gratitude and

appreciation especially to my supervisor, Mr. Zamri Bin Mohamed for his constant

guidance, invaluable knowledge, and constructive idea in leading me to accomplish

this project.

Besides that, I wish to express my sincere appreciation to the teaching

engineer of the Automotive Laboratory, especially to Mr. Faizul Shahidan Bin

Rajuli, Ismail Bin Ali, Aminuddin Bin Ayub and Mr. Fazli Bin Ismail whom I owe

particular debt of gratitude for his practical suggestion and experience that has

supported me and assisted me in many aspects.

I acknowledge my sincere indebtedness and gratitude to my parents for their

love, dream and sacrifice throughout my life. Special thanks should be given to my

committee members. I would like to acknowledge their comments and suggestions,

which was crucial for the successful completion of this project. All of their helps are

very significant to the success of this project.

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ABSTRACT

Bumper is divided in two types, they are front bumper and rear bumper.

Main function both of them are for absorbing impact by reducing damage and to the

potential for bodily injury during an accident. Rear car bumper system has three

main components. They are the fascia, energy absorber and bumper beam. The fascia

is the outer cover in this system. It is attaches to the quarter panels and rear end panel

of the system. The energy absorber attaches to the bumper beam. The bumper beam

is mounted directly to the vehicle body. These components were reviewed for

differences in shape and construction prior to being assembled to the vehicles. For

this project, rear bumper of PROTON Persona car was chosen to be benchmarking.

Then, the new rear bumper was design by using SOLIDWORK Software in

dimensional of PROTON Persona car. By using FEA tools that is ALGOR software,

the new design was analyzed at three different parts and constant force. Improvement

of rear bumper design was compared based on material used, attachment, analysis on

Stress Von Mises and displacement, installation, buying and repairing cost, and

others. The important result is to improve rear bumper car and to give advantages to

the car users such as remove and installation rear bumper knowledge.

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ABSTRAK

Bumper terbahagi kepada dua jenis iaitu bumper depan dan bumper

belakang. Fungsi utama kedua-dua bumper ini ialah untuk menyerap hentaman untuk

mengurangkan kerosakan dan melindung kecederaan diri ketika berlaku kemalangan.

Sistem bumper belakang sesebuah kereta mempunyai tiga komponen utama.

Komponen-komponen itu ialah fascia, penyerap tenaga dan palang bumper. Fascia

adalah komponen yang paling luar dalam system ini. Fascia bersambung pada

bahagian tengah dan bahagian belakang system. Penyerap tenaga bersambung pada

palang bumper. Palang bumper pula berhubung terus dengan badan kenderaan.

Semua komponen ini yang ditunjukkan adalah berbeza dari segi bentuk dan

pembuatan sebelum dicantumkan ke kenderaan. Untuk projek ini, bumper belakang

kereta PROTON Persona telah di pilih untuk di tanda aras. Kemudian, bumper

belakang yang baru telah dicipta dengan menggunakan perisian SOLIDWORK

berdasarkan ukuran kereta PROTON Persona. Dengan menggunakan perisian FEA

iaitu perisian ALGOR, bumper belakang yang baru dianalisa pada tiga bahagian

berlainan dan pada daya yang kekal. Penambahbaikan bentuk bumper belakang

dibandingkan dengan berdasarkan pada penggunaan bahan, penyambungan, analisa

pada Stress Von Mises dan regangan, pemasangan, kos pembelian dan pembaikian,

dan lain-lain. Kepentingan keputusan adalah untuk menambahbaikan bumper

belakang kereta dan untuk memberi lebih keuntungan kepada penguna-penguna

kereta seperti pengetahuan untuk membuka dan memasang bumper belakang.

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TABLE OF CONTENTS

Page

SUPERVISOR’S DECLARATION ii

STUDENT’S DECLARATION iii

DEDICATION iv

ACKNOWLEDGEMENTS v

ABSTRACT vi

ABSTRAK vii

TABLE OF CONTENTS viii

LIST OF TABLES xi

LIST OF FIGURES xii

LIST OF ABBREVIATIONS xv

CHAPTER 1 INTRODUCTION

1.1 Introduction 1

1.2 Problem Statement 2

1.3 Objective 2

1.4 Limitation 3

CHAPTER 2 LITERATURE REVIEW

2.1 Rear car bumper system 4

2.2 Bumper fascia 6

2.3 Energy absorber 7

2.4

2.5

2.6

Bumper beam

Impact test

Material and cost

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CHAPTER 3 METHODOLOGY

3.1 Introduction 15

3.2 Project background 15

3.3 Project flowchart 16

3.4

3.5

Benchmark rear car bumper system

Designing improvement rear car bumper system

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3.6 Analysis the improvement design

3.6.1 Fascia impact analysis

3.6.2 Bumper beam impact analysis

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3.7 Comparison result 25

CHAPTER 4 RESULTS AND DISCUSSION

4.1 Benchmark activity 26

4.2 Improvement design 31

4.3 Bill of material 32

4.4 Improvement of rear bumper design 33

4.5

4.6

Force calculation

Impact analysis

4.6.1 Fascia impact analysis

4.6.1.1 Discussion

4.6.2 Fascia attachments impact analysis

4.6.2.1 Discussion

4.6.3 Bumper beam impact analysis

4.6.3.1 Discussion

4.6.4 Bumper beam attachments impact analysis

4.6.4.1 Discussion

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CHAPTER 5 CONCLUSION AND RECOMMENDATIONS

5.1 Conclusion 49

5.2 Recommendations 50

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REFERENCES

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APPENDICES 53

A Material properties 53

B Gantt chart 55

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LIST OF TABLES

Table No. Page 4.1 Dimensional of PROTON Persona rear bumper 31 4.2 Bill of material of PROTON Persona rear bumper system 32 4.3 Result of fascia impact analysis 37 4.4 Result of fascia attachments impact analysis 41 4.5 Result of bumper beam impact analysis 44 4.6 Result of bumper beam attachments impact analysis 47

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LIST OF FIGURES

Figure No. Page 2.1 Rear car bumper system 5 2.2 Bumper fascia (Honda Civic) 7 2.3 Energy absorber 9 2.4 Bumper beam (stamping process) 11 2.5 Bumper beam (Roll forming process) 11 2.6 Impact duration as a function of barrier impact speed 12 2.7 Average acceleration as a function of barrier impact speed 13 3.1 Flowchart of project 16 3.2 Fascia 17 3.3 Bumper beam 17 3.4 Vehicle body 18 3.5 Clip 18 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13

Screw Improvement fascia design Improvement bumper beam design Clip design Screw design IGES file for improvement fascia design IGES file for improvement bumper beam design Center impact analysis

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3.14 3.15 3.16 3.17 3.18 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20

Side impact analysis Corner impact analysis Center impact analysis Side impact analysis Corner impact analysis The screws location (upper) The screws location (lower) The 4 clips location at the car body The 4 clips location at the top of fascia The clips location at the rear lamp (at car body) The clips location at the fascia The clips location bottom the fascia Fascia Bumper beam Exploded view of bumper system Current fascia Improvement fascia Current bumper beam Improvement bumper beam Center impact analysis Side impact analysis Corner impact analysis Attachment 1 (current fascia) Attachment 2 Attachment 3

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4.21 4.22 4.23 4.24 4.25 4.26 4.27 4.28

Attachment 4 Attachment 5 Center impact analysis Side impact analysis Corner impact analysis Attachment 1 (current bumper beam) Attachment 2 Attachment 3

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LIST OF ABBREVIATIONS

3D Three Dimension AISI America Iron and Steel Institute FEA Finite Element Analysis FYP Final Year Project KMC Knowledge Management Centre UHSS Ultra High Strength Steel UMP Universiti Malaysia Pahang UTS Ultimate Tensile Strength VPG Virtual Proven Ground

CHAPTER 1

INTRODUCTION

1.1 INTRODUCTION

Bumper is a part of an automotive designed that had at a vehicle. Bumper

comprised an elongated support which can be attached to the front and rear of the

vehicle body and which spans the width of the vehicle body, a shock absorber

extending along the support part and extending towards the front and rear of the

vehicle body in a substantially convex manner, and an elastic exterior shell which

can be connected to the support part and which encompasses the front and rear of the

vehicle in an approximate U shape, covering the side of the support part opposite the

side facing the front and rear of the vehicle body where in the support part has a

middle section that can be firmly supported on the vehicle body.

Bumper is divided in two types, they are front bumper and rear bumper. Main

function both of them are for absorbing impact by reducing damage and to the

potential for bodily injury during an accident. For this project, it is focused on the

rear car bumper system. Rear car bumper system has three main components. They

are the fascia, beam, attachment brackets and sometimes energy absorber. The fascia

is the outer cover. It is attaches to the quarter panels and rear end panel. The energy

absorber attaches to the beam. The beam is mounted directly to the vehicle body.

These components were reviewed for differences in shape and construction prior to

being assembled to the vehicles.

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In this project, it is more to the improvement of rear bumper. The

improvement is based on design, material used, attachment and impact testing. It’s

had two types of impact testing. It’s are using barrier impact test and using Finite

Element Analysis (FEA) Software that is ALGOR Software. Analysis using software

was selected to test the design in this project.

1.2 PROBLEM STATEMENT

Rear car bumper system is one of the safety components in a car. But some

people regarded that rear car bumper is just for accessory to a car. The current rear

bumper is very difficult to install to the vehicle body. That why the rear bumper

repairing cost quite expensive. It’s difficult to install and remove because it’s had

many attachments. Another is average car users did not know how to repair or

replace rear bumper when it’s broken. Usually, car users just send their car to the

workshop for repairing or changing the rear bumper.

Nowadays, rear car bumper is quite expensive in aftermarket although it

depends on types of rear car bumper and car. Broken rear car bumper also quite

expensive to replace. When thinking about the price, some people prefer to buy a

non-original bumper because it cheaper than original without thinking about their

safety. It’s dangerous not only to the driver but also to the passengers.

1.3 OBJECTIVE

The main objective of this project is to improve rear bumper design. It will be

designed using Solidwork software. Another main objective is to analyze the

improvement design using Finite Element Analysis Software. The design will be

analyzed in ALGOR software. This project is also to emphasize on the attachment

and installation aspects of rear bumper to the vehicle body. It is designed for easier

assembly steps as well as modifying the attachment design. It also will be designed

for reduce of repairing cost.

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Another objective is to design it more effective for a protection. It will be

designed to increase impact absorbing behavior and to decrease car body

deformation.

1.4 LIMITATION

During this project, some limitations were occurred. One of them is no books

and journals about the bumper system in Knowledge Management Center (KMC) of

University Malaysia Pahang (UMP). This gave difficulty to make project references.

So, another alternative is by searching the journals from internet. Other, Three

Dimension (3D) Scanner had problem and under maintenance. So, for continue this

project, manual dimensional was using.

CHAPTER 2

LITERATURE REVIEW

2.1 REAR CAR BUMPER SYSTEM

Bumper system including a bumper cover, an energy absorber formed of a

synthetic resin material through a foam molding process, an impact beam for

supporting the energy absorber, the impact beam being formed of a glass mat

thermoplastic and having a U-shaped section, and a stay for connecting the impact

beam to a vehicle body. Tips are formed on front upper and lower portions of the

impact beam, and a web portion is formed on the impact beam between the tips. Tip

insertion grooves in which the tips are inserted are formed on an inner surface of the

energy absorber, and a pressure receiving surface corresponding to the web portion is

formed on the inner surface of the energy absorber. (Choi, W.J. et al., 2003).

A bumper for a motor vehicle comprising an elongated support which can be

attached to the front or rear of the motor vehicle body and which spans the width of

the motor vehicle body, a shock absorber extending along the support part and

extending towards the front or rear of the motor vehicle body in a substantially

convex manner, and an elastic exterior shell which can be connected to the support

part and which encompasses the front or rear of the motor vehicle in an approximate

U shape, covering the side of the support part opposite the side facing the front or

rear of the motor vehicle body wherein the support part has a middle section that can

be firmly supported on the vehicle body, and two lateral shells adjacent to the sides

of the middle section and extending between the shock absorber and the exterior

shell, wherein the shock absorber is constructed with separate absorbing elements in

sections, whereby a central absorbing element can be inserted in a hollow that is

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limited by the exterior shell and the middle section of the support part, and whereby

two lateral absorbing elements can be inserted into the lateral shells of the support

part that is open to the vehicle body, and wherein the lateral absorber elements have

lock notches at their faces that can lock into locking points on the support part.

(Nuber, W., et al., 1997).

A bumper structure for a vehicle includes a bumper reinforce secured to a

body of the vehicle and a bumper fascia extending along and covering the bumper

reinforce. The bumper reinforce has a front vertical wall portion having a first

opening, a horizontal upper wall portion and a horizontal bottom wall portion. A first

flange extends from an edge of the first opening toward the body and has an

engaging portion which is bent toward the first opening. A second flange extends

from the edge of the first opening toward the body and is spaced from the first flange

to have a certain space there between. A third flange extends from the bumper fascia

toward the bumper reinforce, and in so sized as to be inserted into the first opening

and to be tightly interposed between the first and second flanges. The third flange

has a second opening for receiving therein the engaging portion of the first flange. A

fourth flange extends from the bumper fascia toward the bumper reinforce.

(Kawaguchi, Y., 1991).

Figure 2.1: Rear car bumper system

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2.2 BUMPER FASCIA

A construction is disclosed for a component for an automotive bumper

selected from the group consisting of an automotive bumper, a bumper fascia and a

bumper guard, said construction comprising a laminate construction of a thin

substantially rigid metal outer shell supported by a substantially rigid, resiliently

deformable plastic backing bonded to said shell over substantially the entirety of an

inner surface of the shell. The plastic backing comprises a thin intermediate layer of

ethylene acrylic acid co-polymers and a backing layer of Surlyn ionomers. Also

disclosed is a process for bonding Surlyn ionomers to stainless steel through use of

said intermediate layer. (Placek, V., 1984).

One embodiment is a bumper fascia support for supporting a motor vehicle

bumper fascia where in the bumper fascia generally has a U-shaped transverse cross-

section with an upper skirt and a lower skirt. The bumper fascia support has a front

side and a back side relative to its position on the motor vehicle and comprises an

elongated platform and at least one base member connected to the elongated

platform. The platform is adapted to be attached to the upper skirt of the U-shaped

bumper fascia and has an upper surface and a lower surface, the upper surface being

adapted for supporting the upper skirt of the U-shaped bumper fascia. The base

member is adapted to be attached to the lower skirt of the U-shaped bumper fascia. A

second embodiment is a bumper fascia support and reinforcement assembly for

supporting and reinforcing a motor vehicle bumper fascia. The bumper fascia

support and reinforcement assembly comprises an elongated bumper fascia support

and an elongated reinforcement. (Birka, M.P., Dermidoff, G.C., 1994).

An attaching device and method of a bumper face comprising a first hole for

positioning formed in a front end member of a vehicle body, a second hole for

positioning formed on each of lower faces of left-hand and right-hand fender panels,

a first projection for positioning forming on a front end panel portion of the bumper

face facing to the vehicle body side and extending backward, and a second projection

for positioning vertically formed on each of upper faces of left-hand and right-hand

side panel portions of the bumper face, the front end panel portion being moved in an

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inclining posture of the bumper face and being engaged with the front end member

by fitting the first projection into the first hole, thereafter, the rear end sides of the

side panel portions being moved upward with the first projection as a fulcrum, and

the second projection being fitted into the second hole, thus, the upper faces of the

side panel portions being respectively engaged with the lower faces. (Inada, T.,

Nishimoto, S., 1997).

Figure 2.2: Bumper fascia (Honda Civic)

2.3 ENERGY ABSORBER

An energy absorbing bumper for protecting an object from a collision is

disclosed which has a compressible cellular core having a plurality of relatively large

spaced apart cavities extending from the back side at least partially through the

cellular core and a resilient outer skin enclosing the compressible core. (Mahfet, M.,

Trappe, A., 2001). An energy absorbing system for a vehicle includes an elongated

energy absorber including a flanged frame for attachment to a reinforcing beam and

a body including a plurality of spaced apart tunable crush boxes capable of

deformation and progressive collapse upon impact for absorbing the energy of

impact. (Weissenborn, M., et al., 2003).

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A bumper system includes a bumper beam having a face and ends, and an

energy absorber mounted on the face. The energy absorber has a one-piece injection-

molded non-foam piece with box sections and interconnecting straps, and a one-

piece or multi-piece foam component securely insert-molded onto the injection-

molded non-foam piece. Different foam molds can be used to form differently

shaped front surfaces on the foam component. By this arrangement, different energy

absorbing systems are provided for vehicles, such as to satisfy the need for different

styling and shapes, while still using the same non-foam piece. By this arrangement,

the energy absorber is a single unit that can be handled and attached to the bumper

beam. At the same time, capital investment in molding dies and tooling is reduced.

(Seegmiller, W., et al., 1976).

A vehicle bumper energy absorbing system is provided that includes molded

foam and at least one integral reinforcing member. The molded foam surrounds the

reinforcing member on at least one side. The molded beam foam is adapted to absorb

impact energy and distribute impact forces to the reinforcing member. Preferably, the

reinforcing member is at least partially or fully encapsulated in the molded foam.

The reinforcing member may be of a plate shape. Fasteners are preferably used to

enable the vehicle bumper energy absorbing system to be mounted to a vehicle

frame. Preferably, the fasteners are integral to the molded bead foam or integral to

the reinforcing member. Preferably, the vehicle bumper energy absorbing system is

adapted to be manufactured in a single step process, wherein the thermoplastic bead

foam encapsulates the reinforcing member. (Carley, M., Sopher, S.R., 2002).