IMPROVEMENT OF REAR BUMPER DESIGN MOHD HAFIZAN BIN MAMAT UNIVERSITI MALAYSIA PAHANG

Transcription

1 IMPROVEMENT OF REAR BUMPER DESIGN MOHD HAFIZAN BIN MAMAT UNIVERSITI MALAYSIA PAHANG

2 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

3 ii 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

4 iii 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

5 iv 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

6 v 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.

7 vi 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.

8 vii 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.

9 viii TABLE OF CONTENTS SUPERVISOR S DECLARATION STUDENT S DECLARATION DEDICATION ACKNOWLEDGEMENTS ABSTRACT ABSTRAK TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES LIST OF ABBREVIATIONS Page ii iii iv v vi vii viii xi xii xv CHAPTER 1 INTRODUCTION 1.1 Introduction Problem Statement Objective Limitation 3 CHAPTER 2 LITERATURE REVIEW 2.1 Rear car bumper system Bumper fascia Energy absorber Bumper beam Impact test Material and cost

10 ix CHAPTER 3 METHODOLOGY 3.1 Introduction Project background Project flowchart Benchmark rear car bumper system Designing improvement rear car bumper system Analysis the improvement design Fascia impact analysis Bumper beam impact analysis Comparison result 25 CHAPTER 4 RESULTS AND DISCUSSION 4.1 Benchmark activity Improvement design Bill of material Improvement of rear bumper design Force calculation Impact analysis Fascia impact analysis Discussion Fascia attachments impact analysis Discussion Bumper beam impact analysis Discussion Bumper beam attachments impact analysis Discussion 48 CHAPTER 5 CONCLUSION AND RECOMMENDATIONS 5.1 Conclusion Recommendations 50

11 x REFERENCES 51 APPENDICES 53 A Material properties 53 B Gantt chart 55

12 xi LIST OF TABLES Table No. Page 4.1 Dimensional of PROTON Persona rear bumper Bill of material of PROTON Persona rear bumper system Result of fascia impact analysis Result of fascia attachments impact analysis Result of bumper beam impact analysis Result of bumper beam attachments impact analysis 47

13 xii LIST OF FIGURES Figure No. Page 2.1 Rear car bumper system Bumper fascia (Honda Civic) Energy absorber Bumper beam (stamping process) Bumper beam (Roll forming process) Impact duration as a function of barrier impact speed Average acceleration as a function of barrier impact speed Flowchart of project Fascia Bumper beam Vehicle body Clip 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

14 xiii 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

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

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

17 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.

18 2 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.

19 3 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.

20 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

21 5 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

22 6 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 crosssection 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

23 7 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).

24 8 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 injectionmolded non-foam piece with box sections and interconnecting straps, and a onepiece or multi-piece foam component securely insert-molded onto the injectionmolded 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).