UNIVERSITI PUTRA MALAYSIA

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UNIVERSITI PUTRA MALAYSIA

DESIGN AND FABRICATION OF A TROPICAL

MOTORCYCLE HELMET

FARAG MOHAMED SHUAEIB

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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

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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

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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 multi-discipline 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

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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

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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.

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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

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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.

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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. M y

profound thanks go to m y 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 woul d 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 uti lizing 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.

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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.

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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.

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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.

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

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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.

RADIN UMAR RADIN SOHADI, Ph.D.

Professor

MEGAT MOHAMAD HAMDAN MEGAT AHMAD, Ph.D.

S.V. WONG, Ph.D.

Lecturer

xii

AINI IDERIS, Ph.D. Professor / Dean

School of Graduate Studies

Universiti Putra Malaysia

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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

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TABLE OF CONTENTS DEDICATION ABSTRACT ABSTRAK ACKNOWLEDGEMENTS APROYAL DECLARA TION LIST OF TABLES LIST OF FIGURES

NOTATIONS AND ABBREVIATIONS

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} 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}

XIV

Page

11 III v Vll XI Xlii XIX xx XXII 5 5 7 13 13 I S 16 20 20 22 22 24 39 39 41 47 4� 49 55 67 67 68 69 70 71

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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 95

3.3 EPP Foam Liner and Optimization Study 96

3.4 Helmet Ventilation Study 102

4 MATERIAL ALTERNATIVES FOR THE NEW MOTORCLE

HELMET 103

4.1 Shell Material Selection 104

4.1.1 Selection criteria 104

4.1.2 Mechanical performance aspects 106

4.2 Liner Material Selection 111

4.2.1 Selection Procedure 1 13

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

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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 Co}_n_dit_ions

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}

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 REFERENCES APPENDIXES VITA XVI J9t) 197 202 202 203 203 205 207 210 214 2 16 216 217 218 219 220 221 223 242 249

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LIST OF TABLES

Table

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

2.6 Standards comparison for motorcycle helmet penetration test requirements

2.7 The M alaysian 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

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

XVII Page

50

53

62

64 1 07

lOS

lOY 130

141

145 ISR

165

178 17Y

ISO

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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

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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). N ote 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

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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 calibration 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

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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

1 36

6.5 The energy- penetration graph for the plastic and the new bio-composite

designs

13

7

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

1 40

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

1 43

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)

1 56

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

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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,

8.4 The contour plot of the acceleration response against the shell thickness

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) 1

9

2

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

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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

A.I

The shape of the tensile test specimen, all dimension are in mm

A.2

Tensile testing of coir composite

A.3

The stress-strain curves of the tensile test for the oil palm and coir composite material

A4

The drop weight impact testing of the natural fiber composites

A

5

The drop weight impact behaviour of natural fiber composite, impact

214 234 235

235 237

velocity 4m/sec, weight 5 . 11 kg 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

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NOTATIONS AND ABBREVIATION

EPS _{is the expanded}_{polystyrene foam} EPP is the expanded polypropylene foam PP is the polypropylene

PE is the polyethylene Pb is the polybutylene

PC is the polycarbonate plastic

ABS is the acrylonitrile butadiene styrene copolymer GRP is the glass reinforced Plastic

CRP is the carbon reinforced Plastic WR is the woven roving

E is the young's modulus

(J is the stress E is the strain

Oy is the foam yield stress

F is the force

D is the relative density of the foam

m is the mass

a is the acceleration

g is the gravitational acceleration is the shell thickness

ED is the densification strain

h is the drop height

A is the contact area under the anvil V is the impact velocity

R is the helmet radius