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Liquid Body Armour. The Shear Thickening Fluid Upgrade. Overview. Nanotechnology in Armor The Basic Kevlar body armor T he Shear Thickening Fluid Physical Mechanism Body Armor Upgrade Properties Applications. Nanotechnology in Armor. Liquid Body Armor
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Liquid Body Armour The Shear Thickening Fluid Upgrade
Overview • Nanotechnology in Armor • The Basic Kevlar body armor • The Shear Thickening Fluid • Physical Mechanism • Body Armor Upgrade • Properties • Applications
Nanotechnology in Armor • Liquid Body Armor • Shear thickening liquid hardens on impact. • Self healing material • Nanocontainers containing liquid form of material placed within the material • Paper-thin bulletproof polymer composite • Material that melts and refreezes under impact.
The Common Body Armour Used • Kevlar Body Armour • Commonly used in warzones • Synthesized viacondensation reaction between 2 monomers: • 1,4-phenylene-diamine (para-phenylenediamine) • terephthaloyl chloride with catalyst.
Properties of Kevlar • High tensile strength of about 3,620 Mpa • Structural steel only has 400MPa! • Lightweight • Limited stab resistance • Sharp point pushes fibres aside • Requires many layers for sufficient protection • Becomes heavy and impedes movement
Shear Thickening Fluid • Breakthrough by • Norman J. Wagner, Ph. D. • Eric D. Wetzel, Ph. D. • The use of Silicon colloidal particles (~450nm) mixed in Ethylene/Polyethylene glycol (EG) carrier fluid. (Non-newtonian liquid) • This leads to the creation of “Impregnated Kevlar Fabric with STF”
The Nanotechnology behind STF • The Silicon particles are evenly distributed. • Van der Waal’s forces of attraction is predominant. • External force overcomes the repulsive particle-particle interactions. • Particles in suspension begin to clump together and hydroclusters.
The Nanotechnology behind STF • Fluid hardens and behave like a solid as the particles collide during hydroclustering • This behavior is strongly dependant on the volume fraction of the Silicon colloidal particles suspended in the carrier fluid.
The Body Armor Upgrade • More impenetrable and better stab resistance • due energy absorbance property • More flexible and lightweight • Due to less kevlar layers required to have the same comparable ballistic protection • High Manufacturability • Due to abundance of base material for STF (Silicon) • Environment resistance • Able to engineer the STF further to become more moisture and thermal resistance
The integration of STF and Kevlar • The STF is first dissolved in organic solvent, ethanol • The kevlar layer is then dipped in the solution and squeezed by a roller to remove excess STF solution. • The kelvlar layer is then left to dry at 150°F to remove the ethanol
Properties of STF Kevlar • Use of Ballistic test • use of the penetration depth to relate to the energy absorbed by target • Projectile impact used should produce shear rate that will induce the transition from fluid to rigid state
Properties of STF Kevlar • Difference in impregnate layering format affects its performance
Properties of STF Kevlar • Superior stab resistance shown with the use of the Ice pick test. • Neat Kevlar has all 5 witness paper penetrated while STF kevlar has none penetrated.
STF Kevlar sheet Properties of STF Kevlar Normal Kevlar sheet
For the normal kevlar fabric Conventional way of energy absorbance such as Yarn tearing, Fiber plastic deformation and fracture. Properties of STF Kevlar • The addition of STF increase the energy absorbance capacity of the kevlar fabric • Provide alternative ways to absorb energy. • STF “grabs” the yarns and thus preventing inter yarn mobility at high strain rates.
Some potential areas of research • Particle Anisotropy • Enhancement of energy absorption using very smaller particles • Changing particle material to lower density and thus weight • Patterning and STF to fabric ratio
Potential and current STF Kevlar applications • Bomb Blanket • Paratrooper boots • Prison guard uniform • Kevlar vest in military • And many more!
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Reference • http://www.baesystems.com/article/BAES_020435/liquid-armour?_afrLoop=764893110948000&_afrWindowMode=0&_afrWindowId=null&baeSessionId=WT3CSHYNndLy25JPM9GST559Fv6dTCKmfCQ3q42d7Sdn410dz6NY!1978008190#%40%3F_afrWindowId%3Dnull%26baeSessionId%3DWT3CSHYNndLy25JPM9GST559Fv6dTCKmfCQ3q42d7Sdn410dz6NY%25211978008190%26_afrLoop%3D764893110948000%26_afrWindowMode%3D0%26_adf.ctrl-state%3D14u4rz9al7_4 • http://en.wikipedia.org/wiki/Kevlar • http://blogs.dickinson.edu/mindmeetsmatter/category/nanotechnology-in-kevlar/ • https://www.ccm.udel.edu/STF/index.html • http://en.wikipedia.org/wiki/Dilatant • http://blogs.dickinson.edu/mindmeetsmatter/2010/12/01/other-uses/ • http://curiosity.discovery.com/question/other-uses-stf • http://hypertextbook.com/facts/2004/KarenSutherland.shtml • http://www.isracast.com/article.aspx?id=28 • http://theweek.com/article/index/236550/the-bulletproof-super-material-thats-paper-thin • http://civil.iisc.ernet.in/nsglec2013.pdf