ENHANCEMENT OF SPIKE AND STAB RESISTANCE OF FLEXIBLE ARMOR USING ...

158 Pages·2009·8.42 MB·English

ENHANCEMENT OF SPIKE AND STAB RESISTANCE OF FLEXIBLE ARMOR
USING NANOPARTICLES AND A CROSS-LINKING FIXATIVE
by
Vincent Lambert

A Thesis Submitted to the Faculty of
The College of Engineering and Computer Science
In Partial Fulfillment of the Requirements for the Degree of
Master of Science

Florida Atlantic University
Boca Raton, Florida
April 2009

ACKNOWLEDGEMENTS
I would like to thank Dr. H. Mahfuz for his direction, assistance and guidance in
the preparation of this thesis. I wish to thank the members of the supervisory committee,
Dr. M. Dhanak and Dr. F. Presuel-Moreno, for their valuable recommendations and
suggestions.

Financial support in the form of a research assistantship from the Army
Research Office under the Battlefield Capability Enhancement program, grant
W911NF0520006, is gratefully acknowledged.

I wish to thank my friends and lab mates for their valuable support. I would also
like to sincerely thank my family for their advice, support and unconditional love
although I am far from away from home.
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ABSTRACT
Author: Vincent Lambert
Title: Development of Flexible Body Armor using
SiO nanoparticles and cross-linking fixatives
2
Institution: Florida Atlantic University
Thesis Advisor: Dr. Hassan Mahfuz
Degree: Masters of Science
Year: 2009
A novel approach has been introduced in making flexible armor composites.
Armor composites are usually made by reinforcing Kevlar fabric into the mixture of a
polymer and nanoscale particles. The current procedure deviates from the traditional
shear thickening fluid (STF) route and instead uses silane (amino-propyl-trimethoxy
silane) as the base polymer. In addition, a cross-linking fixative such as Glutaraldehyde
(Gluta) is added to the polymer to create bridges between distant pairs of amine groups
present in Kevlar and silated nanoparticles. Water, silane, nanoparticles and Gluta are
mixed using a homogenizer and an ultra-sonochemical technique. Subsequently, the
admixture is impregnated with Kevlar – by passing the heating and evaporating
processes involved with STF. The resulting composites have shown remarkable
improvement in spike resistance; at least one order higher than that of STF/Kevlar
composites. The source of improvement has been traced to the formation of secondary
amine C-N stretch due to the presence of Gluta.
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TABLE OF CONTENTS
CHAPTER 1.INTRODUCTION ......................................................................................... 1
1.1 Literature Review ................................................................................................ 2
1.2 Scope of Thesis .................................................................................................... 9
CHAPTER 2.MATERIALS, EQUIPMENT AND SYNTHESIS ..................................... 11
2.1 KM-2 Kevlar® Fabric ....................................................................................... 11
2.2 Correctional Kevlar® ........................................................................................ 12
2.3 Spectra® ............................................................................................................ 14
2.4 Polyethylene Glycol (PEG) ............................................................................... 16
2.5 Silica Nanoparticles ........................................................................................... 16
2.6 Organosilane ...................................................................................................... 18
2.7 Glutaraldehyde .................................................................................................. 19
2.8 High Intensity Ultrasonic Liquid Processor ...................................................... 22
2.9 Synthesis of the Silated-Nanoparticles-Glutaraldehyde -Fabric Composites.... 23
CHAPTER 3.EXPERIMENTATION ............................................................................... 25
3.1 NIJ Stab Test ..................................................................................................... 25
3.1.1 Test Methodology .......................................................................................... 26
3.1.2 Procedure ....................................................................................................... 28
3.2 Scanning Electron Microscope (SEM) .............................................................. 30
3.3 Fourier Transform Infrared Spectroscopy (FTIR) ............................................. 31
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3.4 Mechanical Testing ........................................................................................... 31
3.4.1 Testing procedure .......................................................................................... 31
3.5 Flexibility Test ................................................................................................... 33
CHAPTER 4.RESULTS & DISCUSSION ....................................................................... 35
4.1 Introduction ....................................................................................................... 35
4.1.1 STF performances ......................................................................................... 35
4.1.2 Removal of Polyethylene Glycol (PEG) ....................................................... 36
4.1.3 Introduction of Silane-Silica-Glutaraldehyde Systems ................................. 39
4.2 NIJ Stab test ....................................................................................................... 39
4.2.1 NIJ Spike test ................................................................................................. 39
4.2.2 NIJ Knife test ................................................................................................. 41
4.2.3 Studies of various fabric ................................................................................ 43
4.2.4 Hybridization for Optimization ..................................................................... 47
4.2.5 Introduction of CaCo .................................................................................... 52
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4.2.6 Failure Analysis ............................................................................................. 56
4.3 Microscopy ........................................................................................................ 74
4.3.1 Silane-Silica-Gluta/Kevlar Microscopy ........................................................ 74
4.3.2 Evolution of bonding ..................................................................................... 77
4.4 Chemical Analysis ............................................................................................. 80
4.5 Mechanical Testing ........................................................................................... 82
4.6 Flexibility test .................................................................................................... 90
4.7 Discussion .......................................................................................................... 92
CHAPTER 5. FINITE ELEMENT ANALYSYS OF SPIKE PENETRATION ............. 95
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5.1 The Finite Element Method ............................................................................... 95
5.2 Modeling of the spike penetration problem ....................................................... 96
5.3 Elements and mesh generation ........................................................................ 100
5.3.1 SOLID92 ..................................................................................................... 100
5.3.2 SOLID186 ................................................................................................... 103
5.3.3 CONTA178 ................................................................................................. 105
5.4 Determination of the materials properties ....................................................... 107
5.5 Boundary Conditions ....................................................................................... 111
5.6 Results ............................................................................................................. 112
5.7 Discussion ........................................................................................................ 114
CHAPTER 6.CONCLUSION ......................................................................................... 116
6.1 Summary .......................................................................................................... 116
6.2 Future Work ..................................................................................................... 117

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LIST OF FIGURES
Figure 1: (a) Molecular structure of Kevlar (b) aromatic ring (c) amide
group. ...................................................................................................................... 12
Figure 2: A x-ray linear dichroism microscopic view of the cross section
of a Kevlar fiber showing radial symmetry [52, 53]. .............................................. 12
Figure 3: Kevlar Correctional fabric under NIJ Spike test. [49] ...................................... 13
Figure 4: Spectra fibers are made out bright white polyethylene ..................................... 14
Figure 5: Molecular structure for Ultra high molecular weight
polyethylene (UHMWPE)....................................................................................... 15
Figure 6: Molecular formula for PEG where n denotes the molecular
weight. For the current research n=4.2 corresponds to a 200g/mol
average molecular weight. ...................................................................................... 16
Figure 7: Laser-induced CVC to produce nanostructured SiO ....................................... 17
2
Figure 8: Molecular structure of the silane coupling agent .............................................. 18
Figure 9: Molecular structure of the trialkoxysilane coupling agent ............................... 19
Figure 10: Silanol linkages between the polymer and the silica substrate
[57]. ......................................................................................................................... 19
Figure 11: Molecular formula of Glutaraldehyde ............................................................ 20
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Figure 12: Aldol Condensation Reaction ......................................................................... 20
Figure 13: Molecular reaction for cross-linking bonding of aldehyde
groups with silated silica particles .......................................................................... 21
Figure 14: VCX Series Ultrasonic Processor from Sonics [58]. ....................................... 22
Figure 15: The manufacturing procedures. Sonicating the particles and
infusing into the fabric using a sealed bag and finally, oven drying
the fabric composite. ............................................................................................... 24
Figure 16: NIJ115 drop mass [59]. ................................................................................... 26
Figure 17: NIJ115 threat weapons; (a) Engineered Knife Blade P1 (one
cutting edge) (b) Engineered Knife Blade S1 (two cutting edges)
(c) Engineered Spike [59]. ...................................................................................... 27
Figure 18: NIJ115 Composite Backing Material [59]. ..................................................... 28
Figure 19: NIJ115 drop tower and system setup; (a) drop apparatus (b)
drop mass (c) threat weapon (Spike) (d) velocity measurement
zone (e) backing material ........................................................................................ 29
Figure 20: (a) Kevlar composite after impact at 16 Joules (b) impacted
witness paper at various impact energies (c) magnified view of the
impacted witness paper. .......................................................................................... 30
Figure 21: Different directions of the testing samples ..................................................... 32
Figure 22: Samples cut from fabric composites ............................................................... 32
Figure 23: A typical tension test in Zwick ....................................................................... 33
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Figure 24: Flexibility test developed by Lee et Al [64] ................................................... 34
Figure 25: NIJ Spike test of STF based composites [63] ................................................. 36
Figure 26: NIJ Spike test of STF based composites with and without
PEG [65] ................................................................................................................. 38
Figure 27: NIJ Spike test of Kevlar based fabrics [65] .................................................... 40
Figure 28: Failure of the backing material after reaching higher energy
level during NIJ Spike test ...................................................................................... 41
Figure 29: NIJ Knife test graph ........................................................................................ 42
Figure 30: NIJ Spike test for various fabrics .................................................................... 44
Figure 31: NIJ Knife test for various fabrics .................................................................... 45
Figure 32: NIJ Spike test for determination of the best hybrid composite ....................... 48
Figure 33: NIJ Knife test for optimum determination ...................................................... 49
Figure 34: Knife/Spike performance for a 15 layers Kevlar/Spectra
Hybrid ..................................................................................................................... 51
Figure 35: Nanoparticles of CaCO .................................................................................. 53
3
Figure 36: NIJ Spike test of CaCO based composite ...................................................... 54
3
Figure 37: NIJ Knife test of CaCO based composite ...................................................... 55
3
Figure 38: Spike penetration in Spectra composite .......................................................... 57
Figure 39: Melted fibers in Spectra composite ................................................................. 58
Figure 40: Spike penetration in Kevlar composite ........................................................... 59
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