ARMOR AND MATERIALS FOR COMBAT THREAT AND DAMAGE PROTECTION

1. ARMOR AND MATERIALS FOR COMBAT THREAT AND DAMAGE PROTECTION Gwynedd A. Thomas, Ph.D. Auburn University Polymer and Fiber Engineering

2. Some DoD Projects(Dr. Gwen Thomas, P.I.) • US Army Aviation Applied Technology Directorate (Comanche Project, 1998) • US Army ARDEC Picatinny Arsenal (LOSAT Kinetic Energy Missile Protection, 2001) • US Army Air Warrior Program (Air Warrior Vest Upgrade, Phases 1-3, 2002-2006) • US Navy NAVAIR (V-22 Osprey Internal Armor Provision, current) • Army Research Lab follow-on (2009) • AFSOCOM, AFRL, USSOCOM follow-on (2010 ->) • ONR Roadside Bomb Protection (2010)

3. Modern Military Body Armor • The FLAK jacket 1942-1970 • FLAK = Fliegerabwehrkanone (AAA) • This armor was only intended to stop shrapnel Not intended for bullets http://www.usmccollectibles.com/field%20gear.htm

4. 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://www.berettausa.com/product/product_pistols_main.htm http://op-for.com/v-22.jpg

5. Energy delivered by various ammunitions

6. Modern Protective Materials • Fibers • Very light • Very limited • Very flexible • Ceramics • Very strong • Pretty light • Really expensive! • Metals • Very strong • Relatively cheap • VERY heavy

7. 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

8. 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*

9. 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 PIPD Fiber http://www.m5fiber.com/magellan/m5_fiber.htm

10. Ceramics • Aluminum oxide • Silicon Carbide • Boron carbide • Aluminum nitride

11. 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

12. 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

13. 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

14. 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

15. Fragment defense – nonwoven approach Nonwovens allow a great deal of moisture and heat transport compared to tight weaves. This nonwoven does not require plastic resin coatings. • 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 (TechTextil Frankfurt, Thomas and Thompson)

16. 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

17. 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) * Test results 31 August – 1 September 2002

18. Results of V50 testing, 0.13 gram (2 grain) RCC FSP

19. Results of V50 testing, 0.26 gram (4 grain) RCC FSP

20. Results of V50 testing, 1.0 gram (16 grain) RCC FSP

21. Results of V50 testing, 4.15 gram (64 grain) RCC FSP

22. Results of V50 testing, 9 mm, 8.0 gram (124 grain) FMJ

23. US Marines Test ResultsI.E.D.’s 2.2lbs/ft2 sample, range 15 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.

24. US Marines Test ResultsI.E.D.’s (cont) 2.2lbs/ft2 sample, range 5 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.

25. 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

26. Levels III and IVVery high energy projectiles 7.62 x 51 FMJ (.308)

27. 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

28. 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

29. 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 = US Army, ARL Website http://www.arl.mil

30. 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

31. 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

32. A flexible hard armor media • Generation of multiple simultaneous paths • Projectile spreads, fragments • Spall cloud redirected by internal geometrics • Fragment defense by nonwovens Graphic courtesy of Jeff Simon, SRI International US Patent # 5,736,474, “Multistructure Ballistic Material”, Auburn University Thomas., 1997

33. Projectile Impact Sequence How 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.

34. ChaoTech: Hard armor media • Generation of multiple simultaneous paths • Projectile spreads, fragments • Spall cloud redirected by internal geometrics • Fragment defense by ArmorFelt • 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)