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ARMOR AND MATERIALS FOR COMBAT ARMOR AND MATERIALS FOR COMBAT THREAT AND DAMAGE PROTECTIONTHREAT AND DAMAGE PROTECTION
Gwynedd A. Thomas, Ph.D.
Auburn University
Polymer and Fiber Engineering
Some DoD Projects(Dr. Gwen Thomas, P.I.)
1) US Army Aviation Applied Technology Directorate (Comanche Project, 1998)
2) US Army ARDEC Picatinny Arsenal (LOSAT Kinetic Energy Missile Protection, 2001)
3) US Army Air Warrior Program (Air Warrior Vest Upgrade, Phases 1-3, 2002-2006)
4) US Navy NAVAIR (V-22 Osprey Internal Armor Provision, current)
A. Army Research Lab follow-on (2009)
B. AFSOCOM, AFRL, USSOCOM follow-on (2010 ->)
5) ONR Roadside Bomb Protection (2010)
Modern Military Body Armor
• The FLAK jacket 1942-1970
• FLAK = Fliegerabwehrkanone (AAA)– This armor was only
intended to stop shrapnel
Not intended for bulletshttp://www.usmccollectibles.com/field%20gear.htm
Ballistic armor has 2 fields of application
Police and government officials Rated projectile
threats (handguns, long guns)
Armor: light, concealable, flexible
Military applications Threats from
explosive device fragments
High energy projectile threats (smg, rifle, mg)
http://op-for.com/v-22.jpg
http://www.berettausa.com/product/product_pistols_main.htm
Energy delivered by various
ammunitions
0
2000
4000
6000
8000
10000
12000
14000
16000
0.25 0.32
9 mm Makarov
0.380 ACP.38 Special .45 ACP
.22 LR.45 JHP
9 mm FMJ 1159 mm FMJ 124
.40 JHP10 mm JHP
.357 Sig FMJ
7.62 x 25 Tokarev
9 mm FMJ 124 (SMG).357 Magnum JHP.44 Magnum JHP
.22 Magnum.454 Casull.30 Carbine
.45-70
7.62 X 39 FMJ Russian5.56 X 45 FMJ (M-16)
.303 British SP
7.62 X 51 FMJ (.308)7.62 X 63 (.30-06)
.50 BMG
Projectile Type
Energy Joules/cm2
Modern Protective Materials• Fibers
– Very light– Very limited– Very flexible
• Ceramics– Very strong– Pretty light– Really expensive!
• Metals– Very strong– Relatively cheap– VERY heavy
Energy absorption in aramids
Tensile strength 23-28 gpd
Elongation to break 2.5 - 3.5 %
Young’s modulus 500 - 900 gpd
Specific gravity = 1.44 Fibrillates on impact
http://web.umr.edu/~wlf/Synthesis/kevlar.html
Energy absorption in HPPE
Tensile strength 30 - 40 gpd
Elongation to break 2.5 - 3.6 %
Young’s modulus 1400 - 2400 gpd
Specific gravity = 0.97 Usually uniaxially wrapped
and resin encased*
PIPD Fiber
• Poly{2,6-diimidazo[4,5-b4',5'-e]pyridinylene-1,4(2,5-dihydroxy)phenylene}
• Commercial name “M5”• Reputation as the upcoming Rock Star of
ballistic resistant fibers• Tests by U.S. Army Natick Soldier Center
labs indicate very promising likelihood of success in ballistic applications
• But there is little available right now
http://www.m5fiber.com/magellan/m5_fiber.htm
Ceramics
• Aluminum oxide
• Silicon Carbide
• Boron carbide
• Aluminum nitride
Aluminum oxide (Al2O3)• Also known as alumina• Naturally occurring ore of
aluminum• High purity grades make
acceptable armor• Spec. grav. = 3.7 - 3.9 • Less expensive than
other armor grade ceramics
• Is also the material of rubies and sapphires
http://en.wikipedia.org/wiki/Image:Corundum-unit-cell-3D-balls.png
Silicon carbide (SiC)
• Very rare in nature– Found in meteorites
• Very effective in body armor and
• Chobham armor• Much more expensive than
alumina• Spec. grav. = 3.1-3.22• Hardness = 2800 kg/mm2
http://en.wikipedia.org/wiki/Image:Silicon-carbide-3D-balls.png
Boron carbide (B4C)
• Third hardest known material– Diamond = 1– Cubic boron nitride = 2
• Spec. grav. ~ 2.5• Extremely effective in
armor• Very expensive• Hardness = 2900 -
3550 kg/mm2
http://www.csj.jp/journals/chem-lett/cl-cont/c00jun_gif/00060662ga.gif
Aluminum Oxynitride (AlON)
• “Transparent aluminum” or “transparent ceramic”
• Spec. grav. 3.69• Superior to glass and
Lexan in transparent armor– Scratch resistant– Defeats .50 cal AP
• Very expensive ($10-$15/ square inch!)
• Hardness=1850 kg/mm2
Fragment defense – nonwoven approach
Strong weight advantages for nonwoven fabrics over woven fabrics (8+lbs)
Initial commercial introduction of 100% HPPE nonwoven - DSM “Fraglight”, 1995
Initial suggestion of blended nonwoven fabrics Thomas and Thompson, Techtextil
1992 Cordova, Kirkland et al 1994
Fiber blend nonwoven 100% Kevlar nonwoven
Nonwovens allow a great deal of moisture and heat transport compared to tight weaves. This nonwoven does not requireplastic resin coatings.
(TechTextil Frankfurt, Thomas and Thompson)
Energy absorption in HPPE/Aramid fiber blends
Radiated strain energy Transferred by aramid and
HPPE beyond impact area Fibrillation of aramids
But fabric network integrity preserved by non-malleable character of aramid
Phase change induced in the thermoplastic HPPE Resulted in a 30% increase in
performance over the predicted force dissipation behavior Tests performed at DuPont labs, Wilmington, DE
Fragment armor improvements with nonwoven technology
• Results from US Army Aberdeen Proving Grounds test• .22 cal. 1.10 gram,
fragment simulating projectile, steel
• Parameters : • Weight < 3.42 kg/m2• Projectile speed > 425
m/sec (1400fps)• Nonwoven materials were
superior to woven aramid and woven PBO
• Historical development of nonwoven armor-• Original Kevlar 29 = 389
m/sec• Original (1991) blend
yielded 434 m/sec (HPPE, 2nd quality and Kevlar 29)
448 462 477 495 531
400
420
440
460
480
500
520
540
Meters/Second
Twaron .69 lbs/ft2 Zylon PBO .53 lbs/ft2 ArmorFelt M .50 lbs/ft2 ArmorFelt1 .54 lbs/ft2 ArmorFelt M .71 lbs/ft2
Fabric Type
V 50 For Valid Weight Candidates
* Test results 31 August – 1 September 2002
Results of V50 testing, 0.13 gram (2 grain) RCC FSP
1069 1074 1074
900
1000
1100
Meters per Second
(3x3) (4x4) (5x5)Results pairings
0.13 gm RCC V50
Army Specification = 1005m/sec
Results of V50 testing, 0.26 gram (4 grain) RCC FSP
963 963 961
700
800
900
1000
Meters per Second
(3x3) (4x4) (5x5)
Group Pairings
0.26 Gram RCC V50
Army Specification = 823 m/sec
Results of V50 testing, 1.0 gram (16 grain) RCC FSP
760 762 764
600
700
800
Meters per Second
(3x3) (4x4) (5x5)
Group Pairings
1.0 Gram RCC V50
Army Specification = 678 m/sec
Results of V50 testing, 4.15 gram (64 grain) RCC FSP
639 640 640
500
550
600
650
700
Meters per Second
(3x3) (4x4) (5x5)
Group Pairings
4.15 Gram RCC V50
Army Specification = 556 m/sec
Results of V50 testing, 9 mm, 8.0 gram (124 grain) FMJ
582 581 582
400
450
500
550
600
Meters Per Second
(3x3) (4x4) (5x5)
Group Pairings
9 MM V50
Army Specification = 457 m/sec
2 December 2003
US Marines Test ResultsI.E.D.’s
2.2lbs/ft2.2lbs/ft22 sample, range sample, range 15 meters15 meters• Nine fragments impacted the sample
panel – No complete penetration.– 3 large (50-150 grain) fragments impacted
the panel along with six smaller (50 grain or less) fragments.
• One of the large fragments, penetrated three ArmorFelt and 14 aramid layers
– (out of 3 layers of ArmorFelt, 40 layers of Kevlar, 3 layers of ArmorFelt)
• No other large fragments, penetrated deeper than three ArmorFelt layers
• None of the fragments completely penetrated the armor.
2 December 2003
US Marines Test ResultsI.E.D.’s (cont)
2.2lbs/ft2.2lbs/ft22 sample, range sample, range 5 meters5 meters
• 22 fragments impacted the sample panel
– 1 complete penetration.– 2 large (50-150 grain) fragments
impacted the panel along with twenty smaller (50 grain or less) fragments.
• Only one of the two large fragments, completely penetrated the armor
– (3 layers of ArmorFelt, 40 layers of Kevlar, 3 layers of ArmorFelt)
• None of the smaller fragments penetrated the armor.
November 2003 Test conducted under guidance of Maj. A.J.
Butler, USMC (ret)
US Marines Test ResultsHand Grenades
• Tests performed at Quantico, VA• 2 samples tested
– A) Identical to Auburn AW design– B) Heavier than Auburn AW design
• M-67 hand grenade– One detonation each target from 4
feet range
• Results– A) No penetrations on Auburn AW
design type• 22 hits by fragments
– B) 1 penetration on heavier type• 17 hits by fragments
Levels III and IVVery high energy projectiles
7.62 x 51 FMJ (.308)
State of the Art
• SAPI– Small Arms
Protective Insert
• Based on Boron or Silicon Carbide
• Backing made of aramid or HPPE composites
http://en.wikipedia.org/wiki/Image:Sapi_plates.jpg
ESAPI
• Enhanced Small Arms Protective Insert
• Permits protection against armor penetrating bullets
• Was needed protection beginning 2003
http://www.marcorsyscom.usmc.mil/SITES/PMICE/Images/Armor&Load/ESAPI.jpg
Ceramic or metal plate armor spall
As the projectile penetrates the armor fragmentation
(shatter) occurs momentum is
transferred to the particles
a spall cloud forms
Vspall =
Initial penetrationSpall fragment cloud
2 E a (m p + m a ) ρ C d A /m p • m a
US Army, ARL Websitehttp://www.arl.mil
Armor piercing projectiles
Most serious threat to military personnel with body armor
May use either hardened steel or tungsten carbide
Designed as multicomponent (eg) copper sheath lead tip (spall generator) carbon steel interior
Graphic courtesy of Jeff Simon, SRI International
One solution to this problem - Stop the bullets by inducing chaos
A trajectory is a highly ordered kinetic path Targets are destroyed by release of the
kinetic energy where the projectile is aimed
Destabilization can result in degradation of lethality, kinetic energy transfer
A flexible hard armor media
Generation of multiple simultaneous paths
Projectile spreads, fragments
Spall cloud redirected by internal geometrics
Fragment defense by nonwovens
Embedded hard elements inflexible media
Deflecting geometrical surfaces
Graphic courtesy of Jeff Simon, SRI International
US Patent # 5,736,474, “Multistructure Ballistic Material”, Auburn University Thomas., 1997
Projectile Impact SequenceHow the new armor works:In the initial stages of the impact, the projectile enters the vest in the normal manner, with standard ballistic resistant fabrics or thin, high strength ceramic plates distorting the leading end and increasing the projectile drag as it enters.
Upon entry into the geometrics zone, the projectile is turned by the deflecting surfaces.
As it continues along the path, the initially turned leading end is deflected into other paths while the trailing end has not yet experienced the torquing action of the shock waves in the projectile body.
The front portion begins to disintegrate, clearing the way for the rear section to be deflected along similar reverse torqued paths until the projectile is finally totally destroyed and comes to rest in the geometric layer.
In initial tests with this media, both 7.62x39 mm Russian and .30-06 US rifle ammunition have been destroyed at 15 meters distance and less without the use of ceramic front plate facings on the armor package. Both ammunition types were destroyed in multi hit test conditions.
ChaoTech: Hard armor media
Generation of multiple simultaneous paths
Projectile spreads, fragments Spall cloud redirected by
internal geometrics Fragment defense by
ArmorFeltFelt Multiple materials available
ChaoTech reduces the weight of any armor material
7.62x39 API(6 hits)
.30-06 APM2(5 hits)
12.7 mm API(All projectiles impacted at full muzzle velocities)