Forensic Biomechanics

Jules Kieser Director, Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin, New Zealand Michael Taylor Science Leader, Institute of Environmental Science and Research (ESR), Christchurch Science Centre, New Zealand Debra Carr Impact and Armour Group, Department of Engineering and Applied Science, Cranfield Defence and Security, Cranfield University, Defence Academy of the United Kingdom, Shrivenham, Wiltshire, United Kingdom

Series Foreword ix Acknowledgements xi

1 Introduction 1
Jules Kieser

2 Basic principles of biomechanics 7
Jules Kieser

2.1 Forces and motion 9

2.2 Stress and strain 12

2.3 Basics of biomechanical behaviour 17

2.4 Biomaterials and viscoelasticity 21

2.5 Acceleration and impact 25

2.6 Fracture behaviour 26

2.7 Ballistic biomechanics 29

3 Biomechanics of bone and bony trauma 35
Jules Kieser

3.1 Composition of bone 37

3.2 Types of bone 38

3.3 Biomechanical properties of bone 39

3.4 Compressive and tensile fracture patterns 45

3.5 Blunt and sharp force trauma 50

3.6 Ballistic trauma 54

3.7 Living versus postmortem fracture 62

3.8 Bone fracture in infants 64

4 Biomechanics of skin and soft tissue trauma 71
Jules Kieser

4.1 Structure of skin 73

4.2 Mechanical properties of skin 75

4.3 Effect of age 78

4.4 Wounding 80

4.5 Sharp force trauma 81

4.6 Blunt force trauma 85

4.7 Ballistic trauma 88

4.8 Bitemarks 92

5 The mechanics of bloodstain pattern formation 99
Mark Jermy and Michael Taylor

5.1 Introduction to bloodstain pattern analysis 101

5.2 Forces acting on fluids 104

5.3 Dimensionless numbers 114

5.4 Fluid properties of blood 116

5.5 The creation of droplets 118

5.6 Droplet flight 126

5.7 Droplet impact: bloodstain formation 128

6 Fibres and textiles 137
Debra Carr

6.1 Introduction 139

6.2 Fabric layers 143

6.3 Fabric degradation 144

6.4 Ballistic impacts 144

6.5 Sharp impacts 146

6.6 Blunt impacts 149

6.7 Tearing 151

Acknowledgements 153

Index 159