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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).