2

An Overview of Energetic Materials Research at Purdue

University

2

S.F. Son

2

School of Mechanical Engineering, Purdue University, West Lafayette, IN, USA

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PurdueUniversity

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•Landgrantschool•38,000students(29,000UGs,9000Grads)•About600GradstudentsinME

4

FaciliFes:ZucrowLabs•  70yearhistory

– Solid,hybridandliquidrockets

–  Jetengines•  About$9M/yrresearchexpenditures– Rocketandair-breathingpropulsion

– EnergeFcmaterials– Energy

•  About90currentstudents,15faculty

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3

Chaffee Hall

Advanced Propulsion Lab (ZL2)

MAURICE ZUCROW LABORATORIES

Combustion Lab (ZL1)

Propulsion Lab (ZL4)

High Pressure Lab (ZL3)

Storage Bunker

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6

HighPressureLabExpansion

•$8.2MExpansionandremodeling.•ConstrucFontobeginearly2016.•FeaturesfiveaddiFonaltestcells.•Integratedlaserlab

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AerospaceIndustrialResearchPark

•PRFplanstobuilda44,000-square-footfacilitywhereRolls-Roycewilldevelopandtestjetengines•AddiFonalspaceavailableforothers.

•980-acreaerospaceresearchparkapproved•LocalrelatedsmallbusinessesincludeINSpace(rocketpropulsion),Adranos(newEMcompany),En’Urga(diagnosFcs)

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OtherFaciliFes•  BirckNanotechnologyCenter

–  186,000squarefeet,25,000sq.c.Class1-10-100nanofabricaFoncleanroom

–  OpFcalPhotolithography(resoluFonto~2µm)

–  Electron-BeamLithography(resoluFonto~10nm)

–  ReacFveIonEtching(RIE)–  Plasmaetching

•  HerrickLabs–  NoiseandVibraFonControl–  ElectromechanicalSystems–  DiagnosFcsandPrognosFcs–  EnergeFcmaterialsprinFng–  20faculty

•  LaserDiagnosFcsLabs–  Profs.BobLucht,TerryMeyer(arrived

thissummer),andChrisGoldstein(newinMarch)

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EnergeFcMaterialsTeam•  CapabiliFesinexperiments(fabricaFonanddiagnosFcs),simulaFon(mulFple

scales),explosivesdetecFon,etc.–  M.Koppes,DirectorofFireProtec:onEngineering-headofcountybombsquad

–  S.Meyer,ZucrowLabManager,tes:ng

–  S.Son,combusFonofEMs–  R.Lucht,laserdiagnosFcsofpropellants–  T.Meyer,laserandx-raydiagnosFcsofexplosives–  W.Chen,highratemechanicsofEMsandxraydiagnosFcs–  A.Varma,CombusFonsynthesis–  A.Raman,AFM,dynamicsandvibraFonappliedtoEMs–  J.Rhoads,Explosivessensing,thermomechanicsofEMs–  G.Chiu,PrinFngofEMs–  A.Strachan,atomisFcandmolecularsimulaFonsofEMs–  M.Gonzales,mesoscalesimulaFonofEMs–  M.Koslowski,mulFscalemodelingofEMs–  S.Beaudoin,detecFonofexplosives(adhesionofexplosivesatthenanoscale)–  B.Boudouris,advancepolymers–  G.Cooks,ExplosivesdetecFon–  C.Goldenstein(new),diode-basedlaserdiagnosFcsappliedtoEMs

hlps://www.purdue.edu/energeFcs/

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MoleculestoApplicaFon

Hiringchemist!Tailoringingredients&Propellants

Characterizingandperforminguniquedynamicexperiments

RocketmotortesFng

Al=blue,F=red,C=green.

Tailored Al

Novelnitrateester(SMX)

AFOSR,DHS,ARO,ONR,DTRA,NASA,&MDAfunding

PlusIndustrialfunding

InsituhighspeedOHPLIF

WindowedcombusFonvesselEncapsulated nanocatalysts

10 µm

ExplosivesdetecFon

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SomeCurrentProjects•  Hypergolichybrids•  Impactini:atedreac:ves•  EnergylocalizaFon(hot-spots)inexplosives&detecFon•  Coupledacous:candelectromagneFcenergyinsult•  CharacterizaFonofenergeFccocrystals•  Small-scaleCharacterizaFonofHomemadeExplosives•  Core-shellreacFves•  IntegraFonofprintedenerge:cmaterialsandMEMs•  CharacterizaFonoffuelscontaininginsitugrownaluminum

nanoparFclesforramjets•  Nanoscalepropellantingredients

–  HighspeedOHPLIF,modifiedmetalfuels,encapsulatedcatalysts•  Explosivesdetec:on,includingadhesionofexplosives•  Widecollabora:onswithEnerge:cMaterialsteam!

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EXAMPLE:Real-TimeDynamicMeasurementsandCharacteriza:onofMesoscaleDeforma:onandTemperatureFieldsinReac:ng

Energe:cMaterialsunderImpactandPeriodicLoading

Marcial Gonzalez

Research Program Areas v  Mesostructure identification (Chen): 3-D X-

ray computed tomography determines initial sample internal structures at the mesoscale.

v  Deformation field (Chen): Impact experiments with high-speed X-ray imaging record in-situ dynamic deformation at the mesoscale.

v  Property distribution (Rhoads/Son): Scanning laser Doppler vibrometry and infrared thermography characterize the dynamic interactions that occur at the crystal/crystal and crystal/binder interfaces.

v  Temperature distribution (Son/Meyer): Laser-induced phosphorescence methods and infrared imaging measure the temperature field evolution.

v  Micro-,Mesoscale modeling (Gonzalez/Koslowski): A predictive modeling and simulation capability is developed.

Research Team

Wayne Chen

Marisol Koslowski

Jeff Rhoads

Steve Son

Terry Meyer

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Mesoscalepredic:ngmodelingandsimula:on

•  MesoscalemulF-physicsmodelbasedonaparFclemechanicsapproach.ThemodelindividuallydescribeseachgraininthespecimenandthemulF-physicsisaccountedbycomplexcontactmechanicslaws)

•  Informedbyproposedlowerscalemodels.•  Calibratedandvalidatedwithproposed

in-situexperimentalcapabiliFes.

FY15–Researchplan

•  Developmentof3Delasto-plasFccontactlawsforgrain/grain,grain/binder,grain/wall,andbinder/wallinterfaces.

•  StudyofweakshockpropagaFonfordifferentmixturesfracFons,polydispercity,andimpactvelociFes.

•  ExtensionofnonlocalcontactmechanicsformulaFonstoelasto-plasFcgrains.

MulFscalepredicFvemodelingandsimulaFonsMarcialGonzalezandMarisolKoslowski

Grainswithlargestcontactforcesandpressures

VolumeoccupiedbygrainsduringpropagaFonofaweakshock[%}

ProjecFlepressureand

reacFo

natbackandlateralw

alls

40kelasto-plasFcgrains

SIGEFF

5.5E+085.3E+085.1E+084.9E+084.7E+084.5E+084.3E+084.1E+083.9E+083.7E+083.5E+08

dislocaFondynamics

polycrystallineplasFcity

PhasefielddamagemodelCrackpropagaFoninpolymerbinder

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Real-:meDeforma:on,Damage,andTemperatureMeasurements

Chen/Son/Meyers

(A) (B)

SynchrotronX-ray

355-nmLaserIrradiation

DynamicLoading

ICMOS#2

ICMOS#1

EnergeticMaterialSpecimen

X-rayPCIHigh-speedCamera

High-speedOpticalCamera

v  Need for Real-time Visualization:

Impact deformation, damage evolution, and temperature measurements are critical physical quantities at meso-scale to understand the response of energetic materials but are currently unavailable.

v  Experimental Approach: We will conduct impact experiments with high-speed X-ray imaging to record in-situ dynamic deformation and damage at mesoscale, and laser-induced phosphorescence method and IR imaging to measure the temperature field evolution.

v  Expected Outcome: Meso-scale measurements of time evolutions of deformation field, damage status, and temperature field.

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Par:cle-ScaleThermomechanicalInterac:onsinEnerge:cMaterials

JeffRhodesandSteveSon

ProjectOverview:•  Thethermomechanicsunderlyinghot-spotformaFonandgrowtharepoorly

understood.•  Preliminaryexperimentalresults[1,2]havedemonstratedthathotspotscan

begeneratedlocally,evenbyweakperiodicexcitaFons.•  ThepresenteffortseekstoaddressthefundamentalquesFonsof“Why?”

and“How?”hot-spotformaFontakesplace,throughajointanalyFcalandexperimentalstudy.

[1]Mares,etal.JournalofAppliedPhysics,2013.[2]Mares,etal.JournalofAppliedPhysics2014.

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Example 2: Nanoscale Propellants MURI Solid propellants are commonly used in space launch vehicles and military missiles

§  The most common oxidizer (ammonium perchlorate, AP) contains: ü 54.5 wt.% oxygen X  30.2 wt.% chlorine

As much as 98% of the chlorine is converted to HCl (hydrochloric acid)

§  The most common fuel (aluminum) forms large molten products (two phase flow losses)

§  Also, high surface area catalysts or metals can lead to rheology and mechanical issues §  Catalysts in binder accelerate aging too!

Image:hlp://commons.wikimedia.org/wiki/File:Peacekeeper_launch.jpg

HCl Formation Issues •  Corrodes the launch area •  Deteriorates the ozone layer

Two-Phase Flow Losses •  Molten particles agglomerate •  Up to 10% loss in motor Isp

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Approach:TailoredParFcles

•  EncapsulatedCatalysts:•  Catalystsocenusedinsolidpropellants

•  Catalystsworkbestwhenincontactwithoxidizer–  So,let’sfabricatecatalystsINSIDEoxidizercrystals!

•  Alloysand“InclusionFuels”

•  Anexampleofan“inclusionfuel”isaluminumwithnanoscalefeaturesofanothercomponent

•  AlloyssuchasAl-Liarealsobeingstudied

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Wealsoneedimproveddiagnos:cs

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PlanarLaser-InducedFluorescence

283.2nmbeam

ExpandedtodiagnosFcsheet

532nmpumplaser

Pressurevessel

310nmfluorescencecollectedat5kHz

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InSituFlameVisualizaFon

•  OHPLIFhasrecentlybeenappliedinsitutopropellantsinourgroup(BobLuchtcollaborator)

•  Wecannowimagetheflamestructures! A:Oxidizerreleasedintoafuel-richgasphase

B:RecessedAPburningfasterthansurroundingmixture.Resultisliced,overvenFlatedflame.

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CatalyzedPropellant

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§  Metals and metalloids have been widely used as neat elemental fuels

§  Modifying and tuning the combustion characteristics of these fuels remains challenging

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Metallized Fuels

§  Can modify reactivity through particle size reduction or surface modification/functionalization (drawbacks)

§  Howonecanobtaintheadvantagesofnanoscalefuelswithoutthedrawbacks?

Major Drawbacks to nanoscale and nanoporous materials •  High Cost •  Difficulty of synthesis (e.g., strong acids, scalability) •  High specific surface area (SSA)

•  Processing issues (unfavorable rheology) •  Rapid oxidation and aging

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Lessons from Liquid Microexplosive Liquids §  Microexplosive liquid fuels have been

investigated since the early 1960’s §  Mixtures of high/low volatility

constituents §  The multicomponent fuels can be either

emulsions (oil/water, left) or missive (heptane/hexadecane, bottom)

§  Has been shown to: §  Promote fuel atomization §  Reduce residence times §  Increase completeness of

combustion

Images:Wang,C.H.,X.Q.Liu,andC.K.Law,Combus'onandmicroexplosionoffreelyfallingmul'componentdroplets.CombusFonandFlame,1984.56(2):p.175-197.;Kadota,T.,etal.,MicroexplosionofanemulsiondropletduringLeidenfrostburning.ProceedingsoftheCombusFonInsFtute,2007.31(2):p.2125-2131.

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Wehavebeenresearchingmicron-scalemetallizedfuelpar:cles/dropletscanhavesimilarproper:estoliquid

fueldropletsthatmicroexplode

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Analogies to Metallized Microexplosive Fuels

Emulsion Fuels •  Mechanical activation

(MA, ball milling) can create composite particles with nanometric inclusion material (e.g., polymer)

Missive Fuels •  Metal alloys can yield

particles that have constituents mixed at the molecular scale

 

Constituents Nanocomposite Particle New Phase Solid Solution

RightImages:hlp://www.spaceflight.esa.int/impress/text/educaFon/Images/SolidificaFon/Intermetallics/Intermetallic%20versus%20alloy.jpg

2424

Mechanical Activation

§  Have been shown to: §  Modify reactivity §  Alter combustion products

(e.g., morphology, composition, etc.) §  Affect the completeness of

combustion §  Micron-scale morphologies

(moderate SSA) §  Can be tailored to achieve desired

material properties and combustion characteristics

Inclusion materials can be interacting or non-interacting

Imagesmodifiedfrom:Sippel,T.R.,S.F.Son,andL.J.Groven,ModifyingAluminumReac'vitywithPoly(CarbonMonofluoride)viaMechanicalAc'va'on.PropellantsExplosivesPyrotechnics,2013.38(3):p.321-326.

C

F

Al

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MA Powders – Solid Propellant

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Nea

t Alu

min

um

MA

Al/P

TFE

Images:Sippel,T.R.,S.F.Son,andL.J.Groven,Aluminumagglomera'onreduc'oninacompositepropellantusingtailoredAl/PTFEpar'cles.CombusFonandFlame,2013(0).

Neat Aluminum MA 70/30 Al/PTFE

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Theoretical Calculations 80/20 Al-Li Alloy Neat Al

Al2O3

Al2O3 AND LiCl

Max ISP ΔhChamber-Exit Temperature Molecular Weight Cl → HCl[sec] [kJ g-1] [K] [kg kmol-1] [%]

Neat Al 264.8 3.4 3614 27.9 98.3Neat Li 263.4 3.3 3204 27.3 1.8

80/20 Al-Li 271.9 3.6 3553 26.2 1.9

Additive

2727

Al-Li Alloy: Theoretical Performance

•  Ideal: 16.9% Li (at 85% Solids Loading) •  20% Li powder is ~stable and commercially available

High HPHS

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Alloy Powders – Solid Propellant (1000 fps)

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26.80/61.48/11.72 Metal/AP/HTPB

Neat Al 80/20 Al-Li Alloy

Appears to be less coarse product agglomeration from the Al-Li propellant

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Alloy Powders – Propellant Surface (9900 fps)

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80/20 Al-Li Alloy Neat Al

Aluminum sinters and agglomerates on the

propellant surface

Al-Li forms a surface melt layer, and the Al-Li droplets

appear to microexplode

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Alloy Powders – Shattering Microexplosion

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The lithium boils within the molten Al-Li, shattering the liquid droplets

AP P

ropellant C

O2 Laser in A

ir (213 W

cm-2)

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MA Powders – Microexplosion Mechanism

31

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MA Powders - Explosive Shock Ignition

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Explosive Shock Ignition Experiment – MA 70/30 Al/PTFE

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Example3:Thermomechanics

•  Emphasisonpre-reac'onmechanicsinplasFc-bondedexplosives

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Bulk-scale(Low-frequency)

Par:cle-scale(Highfrequency)

Elas:cBinder

Energe:cCrystals

34

TheTakeaway

•  Atthebulk-scale:–  Homogenizedmaterialmodelsappeartosuffice–  Thethermomechanicsappeartobeclassical–  Aginganddamageappeartodominatetheresponse

•  Atthepar'cle-scale:–  DetailedparFcle-scalemodelsnecessary–  Hot-spotthermomechanicsrelevant– WeakexcitaFonscanhavedramaFceffectsduetoenergyconcentra'on

34

35

Bulk-ScaleThermomechanics

•  Fabricatedsurrogatematerials–  HTPB/NH4ClforHTPB/AP–  VariedvolumefracFons–  Variedgeometry

•  Excitedstructuralresonances•  Measured

– Mechanicalresponse–  Thermalresponse

•  Correlatedresponses

35

36

ParFcle-ScaleThermomechanics

36

37

ParFcle-ScaleThermomechanics

37

PBX9501,215R

PBX9501,3400A

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ParFcle-ScaleThermomechanics

38

PBX9501,215R

PBX9501,3400A

TwopotenFalpathwaystoheaFng?Thehammerandthescalpel

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ParFcle-ScaleThermomechanics

39

•  Sylgard184embeddedwithvariousenergeFcandinertparFcles–  4.0x6.7x9.0mm–  ParFcles~1.0mmbeneathsurface

•  Piezoelectricultrasonictransducersepoxiedtoeachsample–  RadialexcitaFon–  215kHzresonance

40

ParFcle-ScaleThermomechanics

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210.39kHz 983.45kHz

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ParFcle-ScaleThermomechanics

41

42

ParFcle-ScaleThermomechanics

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AP(550-700μm)sampleat10Walsofsuppliedelectricalpowerat215kHz.TotalFmetoigniFon~8seconds.

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ParFcle-ScaleThermomechanicalInteracFons

43

44

Trace ExplosivesDetecFonResearchatPurdue

SteveBeaudoin

ProfessorofChemicalEngineeringAcademicDirector,TeachingandLearningTechnology

PurdueUniversityWestLafayePe,IN47907sbeaudoi@purdue.edu

45

Overall Goals

• MeasureadhesionbetweenexplosivesresiduesandrepresentaFvesubstrates

• Modelobservedadhesion•  QuanFfyeffects

•  ResidueandsubstratemechanicalproperFes•  Residueandsubstratetopography•  EnvironmentalcondiFons(humidity)

•  Relateadhesionbehaviortoresidueremovalduringcontactsampling•  OpFmizecomposiFonandstructureofswabs•  OpFmizeswabbingprotocols

•  Developbenignsurrogatesforliveexplosives

46

Viscous effects

Surface effects

Historical Model: Composite Deformation

"#$↑∗ = '↓1 + '↓2 )*↑+ 

)*= ,- ↓* .↓32 /γcos0  

Iveson, S. M., & Page, N. W. (2004). Brittle to Plastic Transition in the Dynamic Mechanical Behavior of Partially Saturated Granular Materials. Journal of Applied Mechanics, 71(4), 470–475.

Peak flow stress

Surface effects

"#$↑∗ = 1↓2 .↓32 /γcos0  

47

106

105

104

103

102

101

100

Simulated Explosives

1.E-06 1.E-04 1.E-02 1.E+00 1.E+02 1.E+04 1.E+06

Dim

ensi

onle

ss p

eak

flow

stre

ss, (

-)

Capillary number (-)

)*= viscous effects/surface effects 

"#$↑∗ = peak Alow stress/surface effects 

BehaviorconsistentwithexisFngtheory

48

Viscosity of Explosives Binders

0

150

300

450

0 20 40 60 80 100

Visc

osity

(Pa*

s)

Shear rate (1/s)

0

500

1000

1500

2000

2500

0.0 2.5 5.0 7.5 10.0

Visc

osity

(Pa*

s)

Shear rate (1/s)

Semtex H binder

C-4 binder

49

Deformation of Simulated Explosive

0.0

2.5

5.0

7.5

0 0.1 0.2 0.3 0.4 0.5

Stress(kPa)

Strain(-)

Stress-strain curve (with error regions) for silica particles (40-150mesh) in PDMS (60 Pa·s viscosity) at 10mm/s compression rate. Axial images shown bottom and left; diametrical are top and right.

50

Comparison to Live C-4

Stress-strain curves (with error regions) for live C-4 (left) and silica particles in simulated C-4 binder (right) at 1mm/s, 10mm/s, and 100mm/s compression rates.

•  Shape of profile for simulant matches that of live material •  Ongoing work: Vary particle size distribution in simulant to match magnitude of

stress response

w 100mm/s

10mm/s 1mm/s

51

Explosives Adhesion

AdhesionbetweenRDXandcoatedaluminumsubstrates

AdhesionbetweenTNTandcoatedaluminumsubstrates

52

Novel Swabs for Contact Sampling

10 µm

10 µm

10 µm

SEMimagesofpolypyrrolepillarsofvaryingaspectraFo.Thedimensionsofthepillarscanbeeasilytunedbychangingthephotolithographictemplate.

53

Acknowledgements

This material is based upon work supported by the U.S. Department of Homeland Security, Science and Technology Directorate, Office of University Programs, under Grant Award 2013-ST-061-ED0001. The views and conclusions contained in this document are those of the authors and should not be interpreted as

necessarily representing the official policies, either expressed or implied, of the U.S. Department of Homeland Security. [10/2013]

Circled: •  Melissa Sweat

•  Dec. 2015 •  Aaron Harrison

•  Dec. 2015 Not pictured: •  Johanna Smith

•  Grad. May 2014 •  Employed at General Mills

•  Andrew Parker •  Grad. May 2016

•  Chris Browne •  Grad. May 2017

•  Alyssa Bass •  Grad. May 2017

54

TheFuture?•  Performance

–  Roomforimprovement-NOT10x,probablynoteven5x

–  That’sOK–afewinchesofextrareachcandeterminetheoutcomeofaboxingmatch

–  TailoredparFcles,tunability,microenergeFcs,andswitchabilityalso

•  Sensi:vity–  IHErequirementswillconFnuetodriveresearch

•  Lifecycle–  Environmental&toxicitydrivers–  AddiFvemanufacturing–  Aging

54

55

AFOSR,DHS,ARO,ONR,DTRA,NASA,&MDAfundingNSF,NDSEG,SMART,NASAFellowships

56

QuesFons?

562