UNIVERSITI PUTRA MALAYSIA

Transcription

1 UNIVERSITI PUTRA MALAYSIA DESIGN AND FABRICATION OF A TROPICAL MOTORCYCLE HELMET FARAG MOHAMED SHUAEIB FK

2 DESIGN AND FABRICATION OF A TROPICAL MOTORCYCLE HELMET By FARAG MOHAMED SHUAEIB Thesis Submitted to the School of Graduate Studies, Universiti Putra Malaysia, in Fulfilment of the Requirements for the Degree of Doctor of Philosophy July 2003

3 DEDICATION To my daughter "Esra" I hope that "ALLAH" will protect you and make your life happy as you gave me the happiness and hope with your smile during the dark days \J

4 Abstract of thesis presented to the Senate ofuniversiti Putra Malaysia in fulfilment of the requirements for the degree of Doctor of Philosophy DESIGN AND FABRICATION OF A TROPICAL MOTORCYCLE HELMET By FARAG MOHAMED SHUAEIB July 2003 Chairman: Associate Professor Abdel Magid Salem Hamouda, Ph.D. Faculty: Engineering The present work is devoted to the design and evaluation of a new crashworthy motorcycle helmet taking into consideration the tropical climate of Malaysia. A multidiscipline literature review on the design problems of motorcycle helmet was carried out and current problems were formulated. Based on the literature review findings, a new shell and liner designs were then proposed to overcome or eliminate these problems. The shell design improvements consisted of developing hybrid natural fiber composite (NFC) shells which were fabricated and evaluated by the standard dynamic penetration test. The results of the new design were found to be satisfactory according iii

5 to the related helmet standards. Three additional methods have been developed to assess the new shells performance in a more quantified manner. These tests are the helmet quasi-static penetration, the helmet rigidity, and the helmet crushing. All these tests were performed and the results confirmed the superior performance of the new natural fiber shell helmets as compared to the market dominant ABS shell helmets. Other factors also supported this design improvement such as cost, and the utilization of environmental friendl y material. In the liner design improvement, the shell was kept to the current ABS shell and the EPP foam as a liner. A 3D finite element algorithm has been developed using LS DYNA-3D software. Based on the simulation results, the helmet with EPP foam liner was found to be satisfactory according to the related helmet standards. A parametric study of the helmet design was performed using the Response Surface Methodology in the Design of Experiment (DOE) statistical method. From this parametric study, the foam thickness and the foam density were found to have more significant effect on the helmet energy absorption than the she]] effects. Design optimizations were also conducted and optimum design was obtained. Finally, thermal analysis for commercially available helmet without ventilation system and the new helmet design with ventilation system were made. from which it was found that helmet ventilation is essential to avoid possible health problems. A design chart for helmet with ventilation system to obtain the minimum cross sectional area required for ventilation nozzles has been developed. This chart is suitable for a IV

6 wide span of amounts of heat generated from the motorcyclist head. The effect of adding the ventilation system to the helmet has been structurally investigated by the finite element simulation and found to positively improve the energy absorption performance of the helmet. v

7 Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai memenuhi keperluan untuk ijazah Doktor Falsafah REKABENTUK DAN PEMBUATAN BAGI TOPI KELEDAR MOTOSIKAL TROPlKA Oleh FARAG MOHAMED SHUAEIB Julai 2003 Pengerusi Profesor Madya Abdel Magid Salem liamouda, Ph.D. Fakulti Kejuruteraan Kajian ini adalah untuk merekabentuk dan menilai topi keledar motosikal yang mengambil kira keadaan iklim tropika di Malaysia. Kajian dasar telah dijalankan terhadap masalah yang dihadapi oleh pengguna motosikal masakini. Daripada kajian tersebut, satu rekabentuk barn cengkerang dan liner telah dicadangkan untuk mengatasi masalah ini. Pembaharnan rekabentuk cengkerang terdiri daripada pembangunan cengkerang komposit hybrid gentian ash (NFC) dimana ia telah difabrikasi dan dinilai dengan ujikaji piawai penembusan dinamik. Keputusan yang diperolehi memenuhi keperluan ujian piawai topi keledar masakini. Selain itu, tiga kaedah telah dibangunkan untuk menilai prestasi cengkerang yang direkabentuk. lni kerana kaedah ujikaiji penembusan dinamik tidak dapat memberikan keputusan yang diharapkan. Kesemua keputusan menunjukkan kekuatan cengkerang gentian asli adalah lebih baik berbanding dengan vi

8 cengkerang ABS. Faktor yang lain juga mcnunjukkan bahawa kclebihan utama rekabentuk ini adalah kos yang rendah dan penggunaan bahan mesra alam. Dalam rekabentuk liner, ABS telah digunakan scbagai cengkerang asal dan elemen tidak terhingga (prototaip maya) berdasarkan LS-DYNA3D telah disediakan bagi pembaharuan rekabentuk cengkerang dengan penyerap EPP. Keputusan simulasi menunjukkan prestasi yang amat memuaskan bagi topi keledar yang direkabentuk. Satu kajian parametrik telah juga dijalankan dengan menggunakan kaedah respon permukaan yang terdapat dalam kaedah statistik Rekabentuk Sesebuah Experimentasi (DOE). Daripada kajian ini, ketebalan dan ketumpatan pcnyerap didapati mempunyaj pcngaruh yang kuat dari segi penyerapan tenaga berbanding cengkerang. Optimasi rekabcntuk juga telah dilakukan. Akhir sekali, anajisis terma telah dilakukan dan perbandingan an tara rekabentuk baru berbanding rekabentuk sedia ada telah dijalankan. Satu carta rekabentuk juga telah dibangunkan untuk mencari luas keratan rentas yang minimum bagi muncung ventilasi. Ini telah didapati bahawa ia amat berguna bagi penyebaran haba pada keratan rent as topi keledar pengguna. Kesan penambahan system ventilasi telah dikaji dan didapati telah menambahkan prestasi penyerapan tenaga pada topi keledar tersebut. VII

9 ACKNOWLDEGEMENTS First of all and before every thing, I submit in humility alld gratitude to my beloved creator" ALLAH '" for having looked after me during all my life and protected me from major catastrophes in this life. A research work of this nature is generally a team work which needs the help, assistance, cooperation, and support from various parties to achieve its objectives. My profound thanks go to my supervisor Associate Professor Dr. Abdel Magid Hamouda for his guidance, advice and constructive criticism throughout the course of this study. His social smartness, friendship, and wisdom have made major impact on the progress of this research work. I would like to record my appreciation for the valuable comments and guidance given by co-supervisors Prof. Ir. Dr. Radin Vmar Radin Sohadi, Associate Prof. Dr. Megat Ahmad Hamdan, and Dr. S. V. Wong towards the completion of the study. Special thanks to Prof. Ir. Dr. Radin Vmar, as a director of the Road Safety Research Center (UPM) of utilizing the facilities of the center for this research work. His respectful dealing and kind management will be a good memory from Malaysia which I will never forget and I wish that the cooperation will be extended in the future. V III

10 My special thanks are extended to Dr. S. V. Wong for his full cooperation and assistance throughout the whole period of the study. I wish to place on record my appreciation to Professor M. S. 1. Hashmi of Dublin University, Ireland, for his help and assistance in the literature review at the early stage of this research work. I wish to express my thanks to Dr Elsadig Mahdi, department of Aerospace Engineering of UPM, for sincere help and assistance during the helmets prototype fabrication, material testing and analysis of the experimental results. I wish to thank all the Faculty of Engineering staff and technicians who participate in my work, particularly Mr. Sharani of the Strength of Materials Laboratory, and Mr. Tajo Arifinn of the Manufacturing Laboratory of UPM, for assistance in performing the experimental work. Many thanks to Professor B.S. Barkawi of UPM, for his help in using the strength of materials laboratory and assistance in the simulation work at a critical stage of this research. Many thanks to all the Road Safety Research Center and ITMA staff and researchers without exclusion who I enjoyed very much of their companionship during my study. ix

11 Finally, I could not find suitable words to express my sincere thanks to my belo\'cu wife Entisar Idris Sharif for here suffering and struggling on looking after me and also taking care of my three children Mohamed, Muad, and Esra. Therefore. I leave this to "ALLAH" to reward here and compensate her in this life and hereatler. x

12 I certify that an Examination Committee met on 22 July 2003 to conduct the final examination of Farag Mohamed Shuaeib on his Doctor of Philosophy thesis entitled "Design and Fabrication of a Tropical Motorcycle Helmet" in accordance with Universiti Pertanian Malaysia (Higher Degree) Act 1980 and Universiti Pertanian Malaysia (Higher Degree) Regulations The committee recommends that the candidate be awarded the relevant degree. Members of the Examination Committee are as follows: ELSADIG MAHDI, Ph.D. Lecturer Faculty of Engineering Universiti Putra Malaysia (Chainnan) ABDEL MAGID HAMOUDA, Ph.D. Associate Professor Faculty of Engineering Universiti Putra Malaysia (Member) RADIN UMAR RADIN SOHADI, Ph.D. Professor Faculty of Engineering Universiti Putra Malaysia (Member) MEGAT MOHAMAD HAMDAN MEGAT AHMAD, Ph.D. Associate Professor Faculty of Engineering Universiti Putra Malaysia (Member) S.V. WONG, Ph.D. Lecturer Faculty of Engineering Universiti Putra Malaysia (Member) S. A. MAGUID, Ph.D. Professor University of Toronto Canada (Independent Examiner) Universiti Putra Malaysia Date: 3 0 SEP 2003 XI

13 This thesis submitted to the Senate of Universiti Putra Malaysia and has been accepted as fulfilment of the requirements for the degree of Doctor of Philosophy. The members of the Supervisory Committee are as follows ABDEL MAGID HAMOUDA, Ph.D. Associate Professor Faculty of Engineering Universiti Putra Malaysia (Member) RADIN UMAR RADIN SOHADI, Ph.D. Professor Faculty of Engineering Universiti Putra Malaysia (Member) MEGAT MOHAMAD HAMDAN MEGAT AHMAD, Ph.D. Associate Professor Faculty of Engineering Universiti Putra Malaysia (Member) S.V. WONG, Ph.D. Lecturer Faculty of Engineering Universiti Putra Malaysia (Member) AINI IDERIS, Ph.D. Professor / Dean School of Graduate Studies Universiti Putra Malaysia Date: 14 NOV 2003 xii

14 DECLARATION ] herby declare that the thesis is based on my original work except for quotations and citation which have been duly acknowledged. I also declare that it has not been previously or concurrently submitted for any other degree at UPM or other institutions. FARAG MOHAMED SHUAEIB XIII

15 TABLE OF CONTENTS Page DEDICATION ABSTRACT ABSTRAK ACKNOWLEDGEMENTS APROYAL DECLARA TION LIST OF TABLES LIST OF FIGURES NOTATIONS AND ABBREVIATIONS 11 III v Vll XI Xlii XIX xx XXII CHAPTER INTRODUCTION 1.1 General 1.2 Importance of Motorcycling In Malaysia 1.3 Commercially Available Motorcycle helmet Motorcycle Helmet types Helmet Design 104 Natural Fiber Resources in Malaysia 1.5 Problem Statement 1.6 Research Objectives 1.7 Thesis Layout IS 16 2 LETERATURE REVIEW 2.0 Introduction 2.1 Head Impact Biomechanics Anatomic Background of Human Head Head Injury 2.2 Motorcycle Helmet Ventilation Introduction Current Designs and Possible Improvement Discussion 2.3 Helmet Manufacturing Shell Manufacturing Helmet Liner Manufacturing 204 Crash Characteristics Motorcyclist Motion during Accident Helmet Investigation for Multi-impact Signs Helmet Roll-Off 2.5 Specification for Protective Helmets for Vehicle Users 2.6 Helmet Mechanical Design XIV

16 2.6.1 Helmet Crash History Helmet Design Parametric Studies and Optimization Helmet Shell Design Issues 76 3 RESEARCH METHODOLOGY l) General Method of Approach Shell Improvement Study 3.3 EPP Foam Liner and Optimization Study Helmet Ventilation Study MATERIAL ALTERNATIVES FOR THE NEW MOTORCLE HELMET Shell Material Selection Selection criteria Mechanical performance aspects Liner Material Selection Selection Procedure SHELL STUDY TESTING APPRA TUS AND PROTORYPE FABR1CAT10N Testing Apparatus CAD/CAM of Helmet Testing Headforms Drop Weight Test Rig Helmet Prototype Fabrication Materials Helmet Prototype Fabrication with Shell Made From Natural Fiber Composite (NFC) EV ALUA TION OF THE BIO-COMPOSITE SHELL HELMETS Experimental Set Up I2l) 6.2 Shell Testing and Results Helmet Penetration Helmet Rigidity Helmet Crushing Conclusions FINITE ELEMENT SIMULATION OF THE NEW DESIGN Introduction Basic Formulation J Material Properties Required for Modelling Mechanical Properties of ABS Material Mechanical Properties of EPP Foam Helmet Components Material Modelling Shell Modelling Modelling of the Liner Helmet Modelling 161 xv

17 7.5.1 EPP Foam Helmet Model Description Loading and Boundary Conditions Simulation Results and Discussion Conel usions In HELMET DESIGN PARAMETRIC STUDY AND OPTIMIZATION Response Surface Basic Theory Response Surface Construction Response Surface Design of Experiments Response Surface Solution Response Surface Design Factors and Their Levels Response Surface Creation and Analysis Response Surface Parametric Study Results and Discussion Response Surface Optimization Conclusions HELMET VENTILATION Introduction 9.2 Description of the Proposed Design 9.3 Thermal Aspects Outdoor Air Conditions Body Heat Released by the Human Head (Metabolic Heat) Other Fixed Inputs Case I: Helmet without Ventilation Calculation Case II: Helmet with Ventilation System 9.4 Conclusions and Future Trends J9t) OVERALLCONCLUSIONS AND FUTURE RECOMMENDATIONS 10.1 Literature Review Findings 10.2 Shell Study Conclusions 10.3 EPP Foam Liner study Conclusions 10.4 Helmet Ventilation Conclusion 10.5 Recommendation for Further Studies 10.6 Study Contributions REFERENCES APPENDIXES VITA XVI

18 LIST OF TABLES Table Page 1.1 Distribution by body region of injuries among Malaysian Motorcyclists 2.1 The progression of the head injury criteria 2.2 The advantages and disadvantages of thermoplastic shells 2.3 Advantages and disadvantages of composite shells 2.4 Advantages and Disadvantages of PP,PE, and Pb Foam Liners 2.5 Advantages and disadvantages of polyurethane foam liner Standards comparison for motorcycle helmet penetration test requirements 2.7 The Malaysian Standard MS 6.1:1969 rigidity test requirements 4.1 The mechanical properties of some natural and synthetic fibers 4.2 Mechanical properties of coir and oil palm composites as compared to synthetic fiber composites 4.3 The mechanical properties of some impact grades of ABS and PC plastics 6.1 Testing details for the three quasi-static helmet tests 6.2 Higher load values for rigidity test of the ABS and the bio-composite shell helmets 6.3 Crushing Load and energy at 20 mm displacement for the tested samples 107 los loy True stress and true strain of data for tensile test of ABS material used in shell modeling 7.2 Helmet finite element model details 8.1 The design matrix levels 8.2 Design matrix in coded units (randomized) 8.3 The design matrix with uncoded units and response values ISR Y ISO XVII

19 9.1 Average outdoor temperature and relative humidity in Malaysia for period from B1 Data matrix in coded units (randomized) before adding response values 243 B2 The design matrix with uncoded units and response values 244 B3 Estimated regression coefficients for acceleration (ACe.) 245 B.4 Analysis of variance for acceleration (ACe.) 246 B5 The fitted surface analysis 247 xviii

20 LIST OF FIGURES Figure Page 1.1 Number of fatalities related to motorcycle accidents,., Total number of registered motorcycles and total number of fatally injured motorcyclists in road crashes Motorcycle helmet types Full face helmet showing the helmet components Shell deformation according to shell type; (a) Rigid shell, II (b) Soft shell 1.6 Thesis layout chart Motorcycle helmet literature review areas Mid-sagittal cross-sectional view of human head and neck Relationship between measured HIC and the occurrence of the skul1 fracture or the extravasations of fluid from blood vessels Tolerance levels for bridging vein disruption (solid lines) and for gliding contusions (dashed line). Note that critical values for peak angular acceleration and angular velocity must both be exceeded for injury to result Schematic view of forced ventilation system layout Ventilation system with EPS foam liner Composite shell making Helmet shell with inserts Molding of resilient foam liner helmet (PP, PE, Pb) Pour in place PU foam helmet mold Schematic drawing of the penetration test Schismatic diagram of helmet rigidity test 88 XIX

21 3.1 The research general method of approach The shell study methodology chart Natural Fiber Helmet prototype Preparation 'n 3.4 The liner study methodology The helmet model cal ibration loo 3.6 The geometrical and modeling parameters calibration The factors considered for the shell material selection The factors effecting the foam liner material selection Densification strain ED plotted against plateau stress Ge (0.25) (the compressive stress at 25 % strain) for commercially available foams. The contours show energy absorption EDGe (0.25) per unit volume The headform model at the drawing stage The tool path of the headform manufacturing process (simulation in the Unigraphics program) (a) The headform and manufacturing and ( b) the final product The Penetration testing headform Four meters height drop weight testing rig which is designed and constructed at the Road Safety Research Centre, University Putra Malaysia, the figures to the right are enlarged focus for the strikers and the steel base Schematic view of the natural fibers helmet shell moulding Helmets fabricated from (a) Coir fibers hybrid with woven roving glass NFC helmet I (b) Coir NFC helmet shell The test set up for the ( a & b)quasi-static penetration, ( c ) rigidity_ and (d & e) crushing tests The dynamic pentration test, a,b, and c shows the test progression,while d,e, and f shows the test in more focus for a natural fiber helmet sample 134 xx

22 6.3 The quasi-static penetration test, a) ABS helmet, b) hybrid oil palm-glass helmet l The load - penetration curves for the ABS and the hio-composite shell helmets The energy- penetration graph for the plastic and the new bio-composite designs Rigidity test for ABS helmet, and oil palm-glass fiber helmets Rigidity test results for natural fibres and ABS shell helmets Helmet crushing tests, a) ABS shell, b) Coir-glass shell, c) EPS liner only The helmet crushing load-displacement graph of glass hybrid natural fibers shell helmets and the ABS shell helmets The helmet crushing energy- displacement graph of glass hybrid natural fibers shell helmets and the ABS shell helmets a ABS experimental tensile stress-strain curves, the first is specimens cut from SloidGold helmet shell, while the second is the literature data b The stress strain data for EPP foam using equation (7.2) The EPP foam model validation The impact simulation and experimental test results for helmet with EPS foam liner and ABS shell material The helmet system models used in this study The helmet system boundary conditions The peak linear acceleration of the headform center of gravity The helmet model with the ventilation system introduced The effect of adding the ventilation system on the impact performance of the EPP foal liner helmet ( Impact speed 6 m/s) The response surface of the acceleration against the foam thickness, and the foam density, ROW: Foam density (kg/m\ T-foam: Foam thickness (mm),t-shell : Shell thickness (mm). Acc: Peak XXI

23 Headform CG acceleration ( g's) The contour plot of the acceleration against the foam thickness and the foam density The response surface of the acceleration against the shell thickness, and the foam density The contour plot of the acceleration response against the shell thickness and the foam density The response surface of the acceleration against the foam thickness. and the Shell thickness The contour plot of the acceleration against the foam thickness and the shell Thickness The response optimization for the absolute minimum acceleration. The graph also shows the desirability lines which can be changed to fit a desired minimum response The response optimization for minimum foam thickness of 15 mm The response optimization for low setting of 4Skg/m ' foam density The response optimization for the high setting of the shell thickness (S mm) General shape of the helmet 20() 9.2 Isometric drawing of the foam liner showing the top configuration of the foam liner and the back side curvature to improve fitness (shallow duct 3-5 mm) Side view of the main design configuration of the foam liner Inside configuration of the ventilation air circulation system S The helmet/head system Thermal representation of the model The predicted internal temperature rise for still air movement and body heat for helmet with ABS shell and EPS foam liner The human comfort chart 209 XXII

24 9.9 Schematic drawing of sensible heating of the moi:-.t air stream entering and leaving the helmet at constant pressure( Simplified model) The internal helmet temperature plotted against nozzle size for a range of metabolic head heat gains 214 A.I The shape of the tensile test specimen, all dimension are in mm 234 A.2 Tensile testing of coir composite 235 A.3 The stress-strain curves of the tensile test for the oil palm and coir composite material 235 A4 A 5 The drop weight impact testing of the natural fiber composites The drop weight impact behaviour of natural fiber composite, impact velocity 4m/sec, weight 5.11 kg t) A6 The drop weight impact testing of natural fiber and GRP composites. impact speed 4m/sec, weight kg. 239 A.6 The drop weight impact behaviour of plastic plates ( a) ABS and ( b) Polycarbonate 24() B.I Standardized residual against frequency 248 B2 Residual against fitted values 248 XXlll

25 NOTATIONS AND ABBREVIATION EPS EPP PP PE Pb PC ABS GRP CRP WR E (J E Oy F D m a g is the expanded polystyrene foam is the expanded polypropylene foam is the polypropylene is the polyethylene is the polybutylene is the polycarbonate plastic is the acrylonitrile butadiene styrene copolymer is the glass reinforced Plastic is the carbon reinforced Plastic is the woven roving is the young's modulus is the stress is the strain is the foam yield stress is the force is the relative density of the foam is the mass is the acceleration is the gravitational acceleration is the shell thickness ED h A V R is the densification strain is the drop height is the contact area under the anvil is the impact velocity is the helmet radius XXIV