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)