UNIVERSITI PUTRA MALAYSIA

UNIVERSITI PUTRA MALAYSIA DESIGN AND FABRICATION OF A TROPICAL MOTORCYCLE HELMET FARAG MOHAMED SHUAEIB FK 2003 58

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

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

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

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

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

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

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

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

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

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

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 1981. 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

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

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

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 1.3.1 Motorcycle Helmet types 1.3.2 Helmet Design 104 Natural Fiber Resources in Malaysia 1.5 Problem Statement 1.6 Research Objectives 1.7 Thesis Layout 5 5 7 13 13 IS 16 2 LETERATURE REVIEW 2.0 Introduction 2.1 Head Impact Biomechanics 2.1.2 Anatomic Background of Human Head 2.1.2 Head Injury 2.2 Motorcycle Helmet Ventilation 2.2.1 Introduction 2.2.2 Current Designs and Possible Improvement 2.2.3 Discussion 2.3 Helmet Manufacturing 2.3.1 Shell Manufacturing 2.3.2 Helmet Liner Manufacturing 204 Crash Characteristics 204.1 Motorcyclist Motion during Accident 2.4.2 Helmet Investigation for Multi-impact Signs 2.4.3 Helmet Roll-Off 2.5 Specification for Protective Helmets for Vehicle Users 2.6 Helmet Mechanical Design 20 20 22 22 24 39 39 41 47 4 49 55 67 67 68 69 70 71 XIV

2.6.1 Helmet Crash History 72 2.6.2 Helmet Design Parametric Studies and Optimization 74 2.6.3 Helmet Shell Design Issues 76 3 RESEARCH METHODOLOGY l)2 3. 1 General Method of Approach 92 3.2 Shell Improvement Study 3.3 EPP Foam Liner and Optimization Study 96 3.4 Helmet Ventilation Study 102 95 4 MATERIAL ALTERNATIVES FOR THE NEW MOTORCLE HELMET 103 4.1 Shell Material Selection 104 4.1.1 Selection criteria 4.1.2 Mechanical performance aspects 106 4.2 Liner Material Selection 111 4.2.1 Selection Procedure 113 104 5 SHELL STUDY TESTING APPRA TUS AND PROTORYPE FABR1CAT10N 117 5.1 Testing Apparatus 117 5.1.1 CAD/CAM of Helmet Testing Headforms 118 5.1.2 Drop Weight Test Rig 12 1 5.2 Helmet Prototype Fabrication 123 5.2.1 Materials 124 5.2.2 Helmet Prototype Fabrication with Shell Made From Natural Fiber Composite (NFC) 124 6 EV ALUA TION OF THE BIO-COMPOSITE SHELL HELMETS 128 6.1 Experimental Set Up I2l) 6.2 Shell Testing and Results 132 6.2.1.Helmet Penetration 132 6.2.2 Helmet Rigidity 138 6.2.3 Helmet Crushing 142 6.3 Conclusions 146 7 FINITE ELEMENT SIMULATION OF THE NEW DESIGN 148 7.1 Introduction 148 7.2 Basic Formulation J49 7.3 Material Properties Required for Modelling 151 7.3.1 Mechanical Properties of ABS Material 153 7.3.2 Mechanical Properties of EPP Foam 154 7.4 Helmet Components Material Modelling 157 7.4.1 Shell Modelling 157 7.4.2 Modelling of the Liner 158 7.5 Helmet Modelling 161 xv

7.5.1 EPP Foam Helmet Model Description 7.5.2 Loading and Boundary Conditions 7.5.3 Simulation Results and Discussion 7.5.4 Conel usions 163 166 In7 172 8 HELMET DESIGN PARAMETRIC STUDY AND OPTIMIZATION 173 8.1 Response Surface Basic Theory 173 8.1.1 Response Surface Construction 175 8. 1.2 Response Surface Design of Experiments 175 8.2 Response Surface Solution 177 8.2.1 Response Surface Design Factors and Their Levels 178 8.2.2 Response Surface Creation and Analysis 178 8.2.3 Response Surface Parametric Study Results and Discussion 181 8.3 Response Surface Optimization 189 8.4 Conclusions 194 9 HELMET VENTILATION 196 9.1 Introduction 9.2 Description of the Proposed Design 9.3 Thermal Aspects 9.3.1 Outdoor Air Conditions 9.3.2 Body Heat Released by the Human Head (Metabolic Heat) 9.3.3 Other Fixed Inputs 9.3.4 Case I: Helmet without Ventilation 9.3.4.1 Calculation 9.3.5 Case II: Helmet with Ventilation System 9.4 Conclusions and Future Trends J9t) 197 202 202 203 203 205 207 210 214 10 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 216 216 217 218 219 220 221 REFERENCES APPENDIXES VITA 223 242 249 XVI

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 50 53 62 64 2.6 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 130 141 145 7.1 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 165 178 17Y ISO XVII

9.1 Average outdoor temperature and relative humidity in Malaysia for period from 1987-1997 204 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

LIST OF FIGURES Figure Page 1.1 Number of fatalities related to motorcycle accidents,.,.. 1.2 Total number of registered motorcycles and total number of fatally injured motorcyclists in road crashes 1987-2000 3 1.3 Motorcycle helmet types 6 1.4 Full face helmet showing the helmet components 7 1.5 Shell deformation according to shell type; (a) Rigid shell, II (b) Soft shell 1.6 Thesis layout chart 19 2.1 Motorcycle helmet literature review areas 20 2.2 Mid-sagittal cross-sectional view of human head and neck 23 2.3 Relationship between measured HIC and the occurrence of the skul1 fracture or the extravasations of fluid from blood vessels 33 2.4 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 36 2.5 Schematic view of forced ventilation system layout 43 2.6 Ventilation system with EPS foam liner 46 2.7 Composite shell making 52 2.8 Helmet shell with inserts 54 2.9 Molding of resilient foam liner helmet (PP, PE, Pb) 62 2.10 Pour in place PU foam helmet mold 64 2.11 Schematic drawing of the penetration test 84 2.12 Schismatic diagram of helmet rigidity test 88 XIX

3.1 The research general method of approach 93 3.2 The shell study methodology chart 96 3.3 Natural Fiber Helmet prototype Preparation 'n 3.4 The liner study methodology 99 3.5 The helmet model cal ibration loo 3.6 The geometrical and modeling parameters calibration 100 4.1 The factors considered for the shell material selection 105 4.2 The factors effecting the foam liner material selection 112 4.3 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 116 5.1 The headform model at the drawing stage 119 5.2 The tool path of the headform manufacturing process (simulation in the Unigraphics program) 120 5.3 (a) The headform and manufacturing and ( b) the final product 120 5.4 The Penetration testing headform 121 5.5 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 123 5.6 Schematic view of the natural fibers helmet shell moulding 126 5.7 Helmets fabricated from (a) Coir fibers hybrid with woven roving glass NFC helmet I (b) Coir NFC helmet shell 127 6.1 The test set up for the ( a & b)quasi-static penetration, ( c ) rigidity_ and (d & e) crushing tests 131 6.2 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

6.3 The quasi-static penetration test, a) ABS helmet, b) hybrid oil palm-glass helmet l36 6.4 The load - penetration curves for the ABS and the hio-composite shell helmets 136 6.5 The energy- penetration graph for the plastic and the new bio-composite designs 137 6.6 Rigidity test for ABS helmet, and oil palm-glass fiber helmets 139 6.7 Rigidity test results for natural fibres and ABS shell helmets 140 6.8 Helmet crushing tests, a) ABS shell, b) Coir-glass shell, c) EPS liner only 143 6.9 The helmet crushing load-displacement graph of glass hybrid natural fibers shell helmets and the ABS shell helmets 143 6.10 The helmet crushing energy- displacement graph of glass hybrid natural fibers shell helmets and the ABS shell helmets 144 7.1a ABS experimental tensile stress-strain curves, the first is specimens cut from SloidGold helmet shell, while the second is the literature data 153 7.1b The stress strain data for EPP foam using equation (7.2) 156 7.2 The EPP foam model validation 162 7.3 The impact simulation and experimental test results for helmet with EPS foam liner and ABS shell material 161 7.4 The helmet system models used in this study 165 7.5 The helmet system boundary conditions 166 7.6 The peak linear acceleration of the headform center of gravity 169 7.7 The helmet model with the ventilation system introduced 171 7.8 The effect of adding the ventilation system on the impact performance of the EPP foal liner helmet ( Impact speed 6 m/s) 172 8.1 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

Headform CG acceleration ( g's) 184 8.2 The contour plot of the acceleration against the foam thickness and the foam density 184 8.3 The response surface of the acceleration against the shell thickness, and the foam density 186 8.4 The contour plot of the acceleration response against the shell thickness and the foam density 186 8.5 The response surface of the acceleration against the foam thickness. and the Shell thickness 187 8.6 The contour plot of the acceleration against the foam thickness and the shell Thickness 188 8.7 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 189 8.8 The response optimization for minimum foam thickness of 15 mm 190 8.9 The response optimization for low setting of 4Skg/m ' foam density 191 8.10 The response optimization for the high setting of the shell thickness (S mm) 192 9.1 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). 200 9.3 Side view of the main design configuration of the foam liner 201 9.4 Inside configuration of the ventilation air circulation system 20 1 9.S The helmet/head system 206 9.6 Thermal representation of the model 206 9.7 The predicted internal temperature rise for still air movement and body heat for helmet with ABS shell and EPS foam liner 208 9.8 The human comfort chart 209 XXII

9.9 Schematic drawing of sensible heating of the moi:-.t air stream entering and leaving the helmet at constant pressure( Simplified model) 212 9.10 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 237 23t) A6 The drop weight impact testing of natural fiber and GRP composites. impact speed 4m/sec, weight 5.1 1 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

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