Study on Ballistic Performance of Hybrid Soft Body Armour

229 Pages·2015·10.03 MB·English

Study on Ballistic Performance of Hybrid
Soft Body Armour

A thesis submitted to the University of Manchester for the degree of
Doctor of Philosophy
in the Faculty of Engineering and Physical Sciences

2015

YANFEI YANG

SCHOOL OF MATERIALS
TABLE OF CONTENTS
LIST OF FIGURES ............................................................................................ 6
LIST OF TABLES ............................................................................................ 11
ABBREVIATIONS ........................................................................................... 12
ABSTRACT ....................................................................................................... 13
DECLARATION ............................................................................................... 14
COPYRIGHT STATEMENT .......................................................................... 15
ACKNOWLEDGEMENT ................................................................................ 16
PUBLICATIONS .............................................................................................. 17
Chapter 1 Introduction ..................................................................................... 18
1.1 Background.................................................................................................. 18
1.2 Research aim and objectives ...................................................................... 19
1.3 Thesis Layout............................................................................................... 21
Chapter 2 Literature review............................................................................. 23
2.1 Background of the ballistic body armour ................................................ 23
2.1.1 Introduction of the ballistic soft body armour ...................................... 23
2.1.2 Ballistic performance evaluation ............................................................ 26
2.1.2.1 Evaluation criteria................................................................................. 26
2.1.2.2 Selection of cartridge and fragment simulator................................... 28
2.1.3 Materials applied for ballistic resistance ............................................... 29
2.1.3.1 Aramid fibres......................................................................................... 30
2.1.3.2 UHMWPE fibres ................................................................................... 32
2.1.3.3 Influence on material properties.......................................................... 33
2.2 Factors influencing on ballistic performance ........................................... 37
2.2.1 Impact response of woven fabric ............................................................ 37
2.2.1.1 A single yarn under impact .................................................................. 37
2.2.1.2 A fabric under impact........................................................................... 38
2.2.2 Fabric structures ...................................................................................... 40
2.2.2.1 Fabric weave structure ......................................................................... 40
2.2.2.2 Inter-yarn friction ................................................................................. 42
2.2.2.3 Uni-directional laminates ..................................................................... 43
2.2.3 Impact conditions ..................................................................................... 45
2.2.3.1 Striking velocity and projectile geometry ........................................... 45
2.2.3.2 Panel size and boundary condition ...................................................... 47
2.3 Ballistic response of the soft armour panel ............................................... 48
2.3.1 Multi-layer panel with uniform layers ................................................... 48
2.3.1.1 Interaction between layers.................................................................... 48
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2.3.1.2 Ballistic performance of the multi-layer armour panel ................. 49
2.3.2 Hybrid armour panel ............................................................................... 50
2.3.2.1 Hybrid materials and hybrid structures ......................................... 50
2.3.2.2 Mechanisms responding to the hybridisation effect....................... 51
2.4 Failure mechanisms of armour panels under ballistic impact ................... 52
2.4.1 Fracture of fibres in ballistic fabric........................................................ 52
2.4.1.1 Fracture mechanisms of polymer fibres........................................................ 52
2.4.1.2 Fracture mechanisms of ballistic fibres......................................................... 53
2.4.2 Failure modes of armour panels ............................................................. 55
2.4.2.1 Woven panel.................................................................................................................... 55
2.4.2.2 UHMWPE UD panel ................................................................................................. 56
2.5 Analysis techniques ...................................................................................................................... 57
2.5.1 Experimental techniques........................................................... 57
2.5.2 Finite Element Analysis (FEA) techniques ............................................ 58
2.5.3 Analytical techniques ............................................................... 60
2.6 Concluding remarks .................................................................................................................... 60
CHAPTER 3 Experimental studies of ballistic armour panels .................................. 63
3.1 Materials specifications and mechanical properties ............................................... 63
3.1.1 Materials specifications............................................................................ 64
3.1.1.1 Twaron yarns ................................................................................................................. 64
3.1.1.2 Twaron fabrics .............................................................................................................. 65
3.1.1.3 Dyneema UD ................................................................................................................... 70
3.1.2 Mechanical properties .............................................................. 71
3.1.2.1 Tensile test........................................................................................................................ 71
3.1.2.2 Shear frame test............................................................................................................ 73
3.2 Ballistic panels preparation .................................................................................................... 75
3.2.1 Woven panels ......................................................................... 75
3.2.1.1 Panels with a single layer fabric ......................................................................... 75
3.2.1.2 Perforated multi-layer woven panels .............................................................. 76
3.2.1.3 Non-perforated woven panels .............................................................................. 76
3.2.2 UD panels .............................................................................. 77
3.2.3 Hybrid panels ......................................................................... 78
3.2.3.1 Different layering sequences of components .............................................. 78
3.2.3.2 Varied amount of each component................................................................... 80
3.2.3.3 Designed hybrid panels ............................................................................................ 81
3.3 Ballistic test ....................................................................................................................................... 82
3.3.1 Ballistic test equipment and procedure ........................................ 82
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3.3.2 Data acquisition ...................................................................... 83
3.3.2.1 Striking velocity and residual velocity ........................................................... 83
3.3.2.2 Energy absorption of the panel........................................................................... 84
3.3.2.3 Ballistic resistance tests............................................................................................ 84
3.3.2.4 Quantification of the indentation in the clay.............................................. 85
3.3.2.5 Backface Signature (BFS) ...................................................................................... 87
3.3.2.6 Indentation volume..................................................................................................... 88
3.4 Photographic observations ...................................................................................................... 88
3.4.1 Impact process observations ...................................................... 88
3.4.2 Post-impact panels observations................................................. 89
3.5 Test data.............................................................................................................................................. 90
3.6 Summary ............................................................................................................................................ 92
CHAPTER 4 Numerical modelling of armour panels under ballistic impact ..... 94
4.1 Introduction of numerical modelling ................................................................................ 94
4.2 FE modelling of armour panels under ballistic impact......................................... 95
4.2.1 FE model of a single layer fabric ................................................ 95
4.2.1.1 Geometry of yarns....................................................................................................... 96
4.2.1.2 FE modelling of fabric under impact .............................................................. 98
4.2.2 FE model of perforated multi-layer panels ................................. 100
4.2.3 FE model of non-perforated multi-layer panels........................... 102
4.3 Material properties ....................................................................................................................103
4.3.1 Introduction of material assignment ......................................... 103
4.3.2 Projectile ............................................................................. 106
4.3.3 Twaron yarns and fabric ........................................................ 106
4.3.4 Dyneema UD laminate............................................................ 110
4.3.5 Clay .................................................................................... 111
4.4 FE results and validation........................................................................................................112
4.4.1 Single layer fabric under impact........................................................... 112
4.4.2 Perforated multi-layer panels ............................................................... 118
4.4.3 Non-perforated multi-layer panels ....................................................... 121
4.5 Summary ..........................................................................................................................................122
CHAPTER 5 Exploration of the ballistic responses of the multi-layer system .124
5.1 The perforated woven panel.................................................................................................124
5.1.1 Fracture time .......................................................................................... 124
5.1.2 Transverse deformation......................................................................... 126
5.1.3 Stress distribution .................................................................................. 129
5.1.4 Energy absorption mechanisms................................................ 134
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5.1.4.1 Energy absorption distribution ...................................................... 134
5.1.4.2 Energy absorption efficiency of each layer ................................... 137
5.2 The non-perforated woven panel................................................................. 139
5.2.1. Transverse deflection ............................................................ 139
5.2.2 Stress distribution ................................................................................. 140
5.2.3 Energy absorption ................................................................. 142
5.2.3.1 Energy absorption distribution and efficiency ............................. 142
5.2.3.2 Influence of the number of layers .................................................. 144
5.2.3.3 Effect of the striking velocity .......................................................... 146
5.2.4 The number of broken layers................................................... 148
5.2.5 Backface Signature BFS and the indentation volume ........................ 150
5.3 Summary........................................................................................................ 151
CHAPTER 6 INVESTIGATION ON FAILURE MODES OF ARMOUR
PANELS UNDER IMPACT .................................................................................. 154
6.1 Twaron woven panel ..................................................................................... 154
6.1.1 Failure characteristics of woven panel....................................... 154
6.1.1.1 A single layer woven fabric............................................................. 154
6.1.1.2 The perforated woven panel ........................................................... 157
6.1.1.3 The non-perforated woven panel ................................................... 162
6.1.2 Failure modes of the woven panel ............................................. 167
6.1.2.1 Failure modes ................................................................................... 167
6.1.2.2 Transverse deformation and stress distribution........................... 168
6.1.2.3 Energy absorption ........................................................................... 169
6.2 Dyneema UD panel ....................................................................................... 170
6.2.1 Failure modes of Dyneema UD................................................. 171
6.2.2 Mechanisms of thermal damage ............................................... 176
6.3 Summary........................................................................................................ 177
CHAPTER 7 DESIGN OF HYBRID ARMOUR PANELS ............................... 179
7.1 Selection of components for hybridisation ................................................. 179
7.1.1 Ballistic performance of fabric with different weave structures ..... 179
7.1.1.1 Effect of areal density...................................................................... 180
7.1.1.2 Weave structures in a single layer fabric ...................................... 181
7.1.1.3 Construction of the multi-layer panel............................................ 185
7.1.2 Ballistic performance of Dyneema UD....................................... 188
7.1.2.1 Energy absorption capacity ............................................................ 188
7.1.2.2 Advantage of small BFS .................................................................. 189
7.2 Layering sequence of hybridisation ............................................................ 191
7.2.1 Hybrid structures .................................................................. 191
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7.2.1.1 Energy absorption ........................................................................... 192
7.2.1.2 Stress distribution............................................................................ 193
7.2.2 Hybrid materials ................................................................... 195
7.2.2.1 Energy absorption ........................................................................... 195
7.2.2.2 Backface Signature (BFS) ............................................................... 197
7.3 Design of hybrid armour panels .................................................................. 197
7.3.1 Design principle of the hybrid armour panels ............................. 198
7.3.2 The function and the range of each group in a panel .................... 200
7.3.2.1Heat resistant layers ......................................................................... 200
7.3.2.2 Energy absorption layers ................................................................ 203
7.3.2.3 Backface Signature (BFS) constraining layers ............................. 206
7.4 Ballistic performance evaluation of the hybrid panels .............................. 208
7.4.1 Hybrid panels manufacture ..................................................... 208
7.4.2 Ballistic performance evaluation of the hybrid panels .................. 209
7.4.2.1 Ballistic resistance tests ................................................................... 209
7.4.2.2 Backface Signature (BFS) tests ...................................................... 210
7.5 Summary........................................................................................................ 210
CHAPTER 8 CONCLUSIONS AND FUTURE WORK .................................... 212
8.1 Conclusions.................................................................................................... 212
8.2. Recommendations for future research work............................................. 215
REFERENCES ....................................................................................................... 217
APPENDIX 1 THE THICKNESS OF SPECIMEN ............................................ 227
APPENDIX 2 FRACTURED YARNS IN TWARON WOVEN PANEL 8F ... 228
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LIST OF FIGURES
Fig. 2.1 Ballistic body armour vest.......................................................................... 24
Fig. 2.2 Energy dissipated in soft armour panel .................................................... 24
Fig. 2.3 Interceptor® body armour ........................................................................ 25
Fig. 2.4 Ballistic limit plot ........................................................................................ 26
Fig. 2.5 BFS measurement NIJ standard-0101.06 ................................................. 28
Fig. 2.6 Cartridges .................................................................................................... 28
Fig. 2.7 Fragment Simulation Projectiles with 2-, 4-, 16-, and 64 grain size....... 29
Fig. 2.8 Tensile properties of different materials................................................... 30
Fig. 2.9 Molecular structures of PPTA ................................................................... 31
Fig. 2.10 Polyethylene unit and orientation of polyethylene................................. 32
Fig. 2.11 Tensile behaviour at different strain rates (a) Kevlar fibres (b)
UHMWPE fibres................................................................................................ 34
Fig. 2.12 Stress-strain response of Twaron® CT716 (110tex, 12.2×12.2ends/cm,
280g/m2) at different strain rates...................................................................... 35
Fig. 2.13 Stress-strain response of 0/90°Dyneema HB26 laminate (SK76 fibres
with polyurethane (PU) matrix) at different strain rates............................... 35
Fig. 2.14 Breaking force of Dyneema® UD SB21 at ageing process at 700ºC and
humidity of 50% ................................................................................................ 36
Fig. 2.15 Projectile impact into body armour ........................................................ 37
Fig. 2.16 Transverse impact on a single ply of fabric (a) side view, (b) top view,
(c) bottom view ................................................................................................... 39
Fig. 2.17 Schematic diagrams of fabrics upon ballistic impact ............................ 41
Fig. 2.18 Wedge through under ballistic impact.................................................... 41
Fig. 2.19 Ballistic impact load on yarns .................................................................. 42
Fig. 2.20 Sketch of the processing steps in the manufacture of the Dyneema® HB
26 laminate material. ......................................................................................... 44
Fig. 2.21 Schematic of Dyneema® UD ..................................................................... 44
Fig. 2.22 Cross-section of Dyneema® HB26............................................................ 44
Fig. 2.23 Three regimes of energy absorption for conical projectiles at different
impact velocity ................................................................................................... 46
Fig. 2.24 Different projectile geometries ................................................................ 46
Fig. 2.25 Energy absorption of fabric with different boundary conditions ........ 47
Fig. 2.26 Multi-layer systems (a) the layered system (b) the spaced system ...... 48
Fig. 2.27 Axial splitting of PPTA fibres .................................................................. 54
Fig. 2.28 Thermal damage of Dyneema fibres ....................................................... 54
Fig. 2.29 Two forces applied on yarns under ballistic impact .............................. 55
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Fig. 2.30 FE model of fabric under impact (a) 3D solid FE mode (b) Pin-joint FE
model，(c) Shell FE model ............................................................................... 59
Fig. 3.1 Tensile curve of Twaron yarn (93tex) ...................................................... 65
Fig. 3.2 The cross-section of yarns in Twaron woven fabric 8F........................... 66
Fig. 3.3 Gaps in five Twaron fabrics (a) 8F, (b) 9F, (c) 10F, (d) 12F, (e) 13F ..... 69
Fig. 3.4 The specimen of Dyneema UD SB71 for tension test ............................... 71
Fig. 3.5 Tensile test .................................................................................................. 72
Fig. 3.6 Tensile stress-strain curve of Dyneema UD .............................................. 72
Fig. 3.7 Pure shear deformation .............................................................................. 73
Fig. 3.8 Shear deformation of the specimen (a) The shear frame (b) Shear
deformation ........................................................................................................ 73
Fig. 3.9 Shear frame test .......................................................................................... 74
Fig. 3.10 Shear tensile curve of Dyneema UD ........................................................ 74
Fig. 3.11 Schematic of experimental ballistic range .............................................. 82
Fig. 3.12 Ballistic test set-up .................................................................................... 82
Fig. 3.13 The indentations in the clay behind (a) Twaron woven fabric panel; (b)
Dyneema UD panel ............................................................................................ 85
Fig. 3.14 Wax mould of the indentation behind Twaron woven panel 8F (left)
24
and Dyneema 7U (right) ................................................................................. 86
20
Fig. 3.15 3D surface of indentations behind the (a) Twaron woven panel 8F (b)
24
Dyneema UD panel 7U .................................................................................... 86
20
Fig. 3.16 BFS measurement ..................................................................................... 87
Fig. 3.17 Measurement of the indentation volume ................................................ 88
Fig. 4.1 Fibres packing in yarns (a) square packing, (b) hexagonal packing...... 96
Fig. 4.2 Schematic of yarn cross-section ................................................................. 97
Fig. 4.3 FE model of Twaron fabric (a) a single yarn, (b) the fabric and
projectile ............................................................................................................. 99
Fig. 4.4.The mesh of FE model (a) fabric and projectile, (b) yarn..................... 100
Fig. 4.5 The FE model of a multi-layer panel....................................................... 100
Fig. 4.6 Hybrid mesh (a) the fine mesh of the primary yarn, (b) the coarse mesh
of the secondary yarn, (c) hybrid mesh in fabric .......................................... 101
Fig. 4.7 Quarter-symmetry FE model of the non-perforated panel under impact
........................................................................................................................... 102
Fig. 4.8 Typical stress-strain curve of elastic-plastic material ........................... 104
Fig. 4.9 linear-elastic response of high performance fibres ................................ 104
Fig. 4.10 FE results of a single layer Twaron fabric............................................ 113
Fig. 4.11 Fracture time of a single layer Twaron fabric under impact ............. 113
Fig. 4.12 Fractured yarns in fabric 8F (a) FE model; (b) post-impact fabric... 114
Fig. 4.13 FE simulation of Twaron fabric 8F under ballistic impact................. 115
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Fig. 4.14 Stress contours of Twaron fabric 8F at different impact time ........... 116
Fig. 4.15 Stress and strain distribution of Twaron fabric 8F ............................. 117
Fig. 4.16 The transverse deformation of fabric 8F at 5.6µs ................................ 118
Fig. 4.17 Energy absorption in three sample sizes.............................................. 119
Fig. 4.18 Energy absorption of Twaron panels with the small model size......... 119

Fig. 4.19 Energy absorption of the FE model with different mesh .................... 120
Fig. 4.20 Energy absorption of Twaron panels with the hybrid mesh............... 120
Fig. 4.21 The clay behind the Twaron panel 11F .............................................. 121
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Fig. 4.22 FE model of the clay behind the Twaron panel 11F ......................... 121
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Fig. 4.23 The indentation produced by the jacket ............................................... 122
Fig. 5.1 The residual velocity history of Twaron panel....................................... 125
Fig. 5.2 The maximum transverse deflection of each layer in Twaron woven
fabric panels (a) 8F, (b) 8F , (c) 8F and (d) 8F ........................................... 128
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Fig. 5.3 Stress distribution on the first layer of the panel 8F ............................ 130
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Fig. 5.4 Stress distribution on the second layer of the panel 8F ........................ 131
3
Fig. 5.5 Stress distribution on the third layer of the panel 8F .......................... 132
3
Fig. 5.6 Stress gradient on panels of (a) 8F , and (b) 8F at 0.3µs under impact
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........................................................................................................................... 133
Fig. 5.7 The energy absorption of woven fabric .................................................. 134
Fig. 5.8 The specific energy absorption (SEA) of woven fabric ......................... 134
Fig. 5.9 The proportion of the dominant forms of energy absorption in fabric 8F
........................................................................................................................... 135
Fig. 5.10 Energy absorption of each layer in panels of (a) 8F , (b) 8F and (c) 8F
3 6 9
........................................................................................................................... 136
Fig. 5.11 Energy absorption efficiency of each layer in panels 8F , 8F and 8F
3 6 9
........................................................................................................................... 138
Fig. 5.12 The maximum transverse deflection of each layer in Twaron panel
11F .................................................................................................................. 139
24
Fig. 5.13 The transverse deformation of fabric layers in Twaron panel 11F . 140
24
Fig. 5.14 The stress distribution on each layer in Twaron woven panel 11F (a)
24
front layers, (b) middle layers and (c) back layers ....................................... 141
Fig. 5.15 Energy absorption of each layer in Twaron woven panel 11F ........ 142
24
Fig. 5.16 Energy absorption efficiency of Twaron woven panel 11F .............. 143
24
Fig. 5.17 Energy absorption of each layer in Twaron woven panel 11F ........ 144
36
Fig. 5.18 Energy absorption of each layer in Twaron woven panel 11F ......... 144
48
Fig. 5.19 Energy absorption of Twaron panels .................................................... 146
Fig. 5.20 Energy absorption distribution at different striking velocities .......... 147
Fig. 5.21 The number of broken layers in non-perforated panels ..................... 148
Fig. 5.22 The number of broken layers in non-perforated panels at different
striking velocities ............................................................................................. 149
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Fig. 5.23 BFS of non-perforated panels with different areal density................. 150
Fig. 5.24 Indentation volume in the clay behind non-perforated panels .......... 151
Fig. 6.1 Impact process of a single layer Twaron fabric ..................................... 155
Fig. 6.2 The perforated Twaron woven fabric ..................................................... 155
Fig. 6.3 Failure morphology of Twaron fibres .................................................... 156
Fig. 6.4 Shear failure appearance of broken Twaron fibres.............................. 157
Fig. 6.5 Impact process of Twaron woven panel 11F ......................................... 157
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Fig. 6.6 Perforated layers in Twaron woven panel 11F ..................................... 158
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Fig. 6.7 Perforated holes on fabric layers of Twaron panel 11F ....................... 159
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Fig. 6.8 Fractured yarns in different layers in Twaron woven fabric panel 11F
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........................................................................................................................... 160
Fig. 6.9 Broken fibres in fabric layers of Twaron panel 11F ............................ 162
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Fig. 6.10 Impact process of the non-perforated Twaron woven panel 11F .... 162
24
Fig. 6.11 The non-perforated Twaron panel 11F (a) post-impact Twaron panel
24
and (b) the indentation in the clay.................................................................. 163
Fig. 6.12 Different extent of crease on fabric layers in Twaron panel 11F ..... 164
24
Fig. 6.13 The impact site of fabric layers in Twaron panel 11F ...................... 165
24
Fig. 6.14 Debris of broken yarns in the Twaron panel 11F ............................. 165
24
Fig. 6.15 Broken fibres in the non-perforated panel 11F (a) ply-1 (b) ply-10 166
24
Fig. 6.16 Schematic of the stress propagation ...................................................... 167
Fig. 6.17 Schematic of the fibre splitting development ....................................... 168
Fig. 6.18 Impact process of a single Dyneema UD layer ..................................... 171
Fig. 6.19 Impact process of non-perforated Dyneema UD panel 11F ............. 171
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Fig. 6.20 Perforated Dyneema UD ........................................................................ 172
Fig. 6.21 Ply splitting on the exit face of the post-impact Dyneema UD 7U : (a)
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Ply splitting, (b) Region 1, and (c) Region 2 .................................................. 173
Fig. 6.22 Fractured fibres on Dyneema UD panel 7U at different magnification
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times: (a)×750 times, (b) ×850 times, (c) ×1800 times, and (d) ×3200 times
........................................................................................................................... 174
Fig. 6.23 Fractured fibres of ply-9 in the post-impact Dyneema UD panel 7U at
24
different magnification times: (a)×25 times, (b)×500 times, (c)×800 times,
and (d)×1000 times........................................................................................... 175
Fig. 6.24 Broken fibres with axial splitting in Dyneema UD panel 7U ........... 175
24
Fig. 6.25 Broken fibres with kink bind in Dyneema UD panel 7U .................. 176
24
Fig. 6.26 The interaction between the projectile and UD layer under impact.. 176
Fig. 7.1 Energy absorption of woven fabric with varied areal density .............. 180
Fig. 7.2 Effect of areal density on energy absorption of woven fabric .............. 181
Fig. 7.3 Energy absorption of 10F (10.4ends/cm) and 10M (10.7ends/cm) ....... 182
Fig. 7.4 Energy absorption of woven fabrics for a given yarn count of 93tex .. 182
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