ergonomics, design and reliability of body armour

262 Pages·2011·11.27 MB·English

CRANFIELD UNIVERSITY
CELIA HUNT WATSON
ERGONOMICS, DESIGN
AND RELIABILITY OF BODY ARMOUR
CRANFIELD DEFENCE AND SECURITY
PhD

CRANFIELD UNIVERSITY
CRANFIELD DEFENCE AND SECURITY
DEPARTMENT OF ENGINEERING AND APPLIED SCIENCE
PhD Thesis
Academic Year 2010-2011
Celia Hunt Watson
ERGONOMICS, DESIGN
AND RELIABILITY OF BODY ARMOUR
Supervisor Professor Ian Horsfall
January 2011
©CranfieldUniversity, 2011.All rights reserved. Nopart ofthis publicationmaybe
reproducedwithout the writtenpermissionofthe copyright holder.

ABSTRACT
The wearing of body amour has become a necessity for many professions and much
work has gone into the optimisation of the mechanics of protection. In the present
study a broader view of the effects of ergonomics, design, reliability and protection
has beentaken.
Three background topics are examined by reference to the literature. First, as an
example of the threats and injury mechanisms that prevail in modern conflicts, the
effects of blast injury to the head are investigated. This is followed by a review of
ergonomictest methods andis completedbyastudyexploringthe influenceof history
onmodernbodyarmour design.
Solutions to some of these problems are then considered. The problem of accurately
measuringimpact loads to the head is investigated and a rigid instrumented head form
is demonstrated. This work showed that the filtering techniques derived from crash
tests usedinthecurrent helmet standards arenot applicabletoballisticimpact events.
A one daywearer trial for police armour based on typical actions carried out bypolice
officers in the performance of their normal duties is developed and demonstrated. A
mechanical flexibility test is shown to give quantitative data but a direct link between
ergonomic rankings and flexibility could not be established. Reliability of both soft
and hard body armour is investigated and for typical armour types it is demonstrated
that a minimal deterioration takes place with time and existing inspections techniques
canhighlight armourthat is belowstandard.
This study has introduced measurement techniques in an attempt to quantify some of
the effects investigated with the intention of using quantitative methods to improve
armourdesignandminimisesomeofthenegativeeffects ofwearingbodyarmour.
i
ii
Acknowledgments
This work has taken some years to complete and without the help and encouragement
of many colleagues, students and friends it would not have been accomplished. I
wouldparticularlyliketo thank thefollowing:
The Metropolitan Police Service Physical Protection Group, for their sponsorship of
the ergonomics and flexibilityparts of this work. I would particularlylike to thank Mr
Paul Fenne, Mrs Jane Barnes-Warden and Constable Shaun Winslade, for their moral
support, good humour and willingness to volunteer to be ‘guinea pigs’ when
developingsomeofthetrials.
The Defence Clothing IPT team, part of the Defence Logistic Organization Bicester
fortheirsponsorshipoftheworkonhelmets and hardandsoft body.
Jane Portal the curator of the Terracotta Army Exhibition at the British Museum
London who arranged myresearch visit and her staff who supplied photographs of the
exhibits. The curators’ of the Armour Collection at the Pitt Rivers Museum, Oxford
who were extremely helpful in allowing me to photograph their exhibits and
providingtheprovenance oftheexhibits.
Professor Ian Horsfall who has always supported my academic endeavours, for 23
years ofhis encouragement,tolerance andmost ofall patience.
Professor Emeritus Tony Belk and Dr Mike Edwards, both of whom encouraged me
toembarkonan academiccareermanyyears ago.
The research and technical team at the Bashforth Laboratory, Mr David Miller, Mr
Steve Champion, Mr Jim Harber and Mr Mike Teagle for their help with the ballistic
testing and Mrs Caroline McKenna and Mrs Claire Lankester for their moral support.
Also, Mrs Paula Bentley for her help with printing the PhD and everyone in the
iii
Department of Engineering and Applied Science for their cheerfulness, kindness and
encouragement.
Myco-authors, thoseof whom Ihave not alreadymentionedabove for the papers that
have resulted from this work, Dr Mike Iremonger, Dr Trevor Ringrose, Mr Brian
Mallonand Miss AnnetteWebb.
All of the military students and police officers who volunteered for the ergonomic
trials fortheirefforts and genuineinterest inthework.
Lastly, but byno means least myfamily, especially myhusband Geoffrey Watson, for
45 years of supporting everything I decide do and being ever ready with a ‘G&T’
My mum another Celia, my son Graeme and daughter Victoria and their children for
keepingmyspirits upandencouragingmeto finish this PhD.
Ithank youall.
iv
Contents
Chapter 1 - Introduction 1
Chapter 2 - Literature Review 7
Part 1. CaseStudyofHead Injuryduetoblast effects 7
2.1 Introduction
2.2Blast loading 7
2.3Casestudies oftheeffects ofblast injury 10
2.4Blast loadingandvulnerabilityoftheheadtoinjury 11
2.5Mechanisms causingBraininjuries 16
2.6Reviewof Injurycriteria 19
2.6.1TheWayneStateUniversityConcussive
ToleranceCurve(WSTC) 19
2.6.2Head InjuryCriterion(HIC) 20
2.7Neckinjurycriteria 23
2.8Effect ofhelmets 24
2.9ReviewofHelmet Standards 26
Part 2.ReviewofErgonomicFactors ofBodyAmour 28
2.10 Introduction 28
2.11Ergonomicstudies 29
2.12Test Methods 31
2.12.1 International BodyArmourTest Standards 32
2.12.2Sizing 35
2.12.3Classification 36
2.12.4Coverage allowancefactor 36
2.12.5Performancelevel codes 37
2.13Assessment aftertrials 38
v
2.13.1RankingFactors 39
2.14Summary 40
References 41
Chapter 3 Historical 49
3.1Development ofArmour 49
3.2Armourfrom natural materials 50
3.3Armourfrom Ancient Civilisations 53
3.4RomanArmour 56
3.5ChineseArmour 58
3.5Medieval Armour 60
3.6JapaneseArmour 61
3.717th-21stCenturyArmour 62
References 67
Chapter 4. Assessment of blunt trauma under ballistic helmets 69
4.1 Introduction 69
4.2Preliminarytrials 69
4.3Radius ofcurvature 70
4.4Headform andcalibrationofZephyr®sensors 72
4.5Calibrationoftheheadform transducer 76
4.6Ballistictests 79
4.7Summary 84
References 85
Chapter 5 - National Police Improvement Agency Ergonomics trial 87
5.1 Introduction 87
5.2ErgonomicWearerTrials -Test Methodology 89
5.2.1Test protocol andQuestionnaire 90
vi