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2 June 2014

Integrity Service Excellence

Joycelyn S. Harrison

Program Manager

AFOSR/RSA

Air Force Research Laboratory

Low Density Materials

US Joint Services & OSD Africa Technical Exchange Meeting

Date: 04 05 2014

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Why Low Density Materials?

If it has structure and rises above the ground, material density is important!

Material density impacts: payload capacity, range, cost,

agility, survivability, environmental impact….

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Low Density Materials

Scientific areas include: materials synthesis and advanced/novel

processing; composite and hybrid materials; nanostructured materials;

interfacial phenomena; multi-scale material modeling and characterization

Program supports: Transformative research targeting advanced materials

that enable substantial reductions in the weight of aerospace platforms and

systems with enhancements in performance and function

Enhanced Specific Capabilities

(performance / pound)

Capability * r -1

1um

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Research Thrusts

1. Structural Lightweighting - taking the

weight out of traditional composites

2. Nanostructured Hybrid Materials - bottom-

up materials design, incorporating what is

needed, where it is needed for optimum

performance

3. Multifunctional Materials - reducing

system weight by designing materials that

do more…. coupling structure and function

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The current cycle time for materials discovery to insertion of 20+ yrs is outpaced by the

demand for advanced aerospace materials….

Time

Polymer Matrix Composites

2-constituents – carbon fiber, polymer

Macroscale processing

Optimized for mechanical performance

Today 1960s

Pro

pert

ies /

Perf

orm

ance

Overarching Materials Challenge

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The current cycle time for materials discovery to insertion of 20+ yrs is outpaced by the

demand for advanced aerospace materials….

Time

Polymer Matrix Composites

2-constituents – carbon fiber, polymer

Macroscale processing

Optimized for mechanical performance

Today 1960s

Increasing material complexity

Reduced development time

Pro

pert

ies /

Perf

orm

ance

Nanostructured Hybrids

N-constituents – metal, polymer,

ceramic, biological

N-dimension – nano, micro, macro

N-property optimization – mechanical,

electrical, thermal, optical, etc

Properties as f(t)

Overarching Materials Challenge

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Portfolio Investment Strategy

– Tackle broad-based, challenges that can offer high pay-off

for future aerospace structures

– Support projects with synergistic experimental and

computational research

– Stimulate academic research connections with AFRL TDs

– Leverage tri-service and interagency collaborative

opportunities

– Encourage international collaboration in appropriate areas

– Leverage STTR and ManTech (Moving Manufacturing Left)

to foster maturation of promising basic research

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Fostering Research Collaborations

DOD COMMUNITY

INTERNATIONAL

AFOSR

Low

Density

Materials

RX, RV, RQ, RW

LRIRs, STTRs,

MURIs,

Workshops,

Reviews, Visits

Lightweight

Structures

Nanostructured

Materials

AFRL

DIRECTORATES

OTHER AGENCIES

NSF/EFRI MOU:

ODISSEI

2 DARE

US-India Tunable

Materials Forum

US-AFRICA Initiative

Reliance 21 Board

Materials and

Processing COI

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Structural Lightweighting

Improved Fibers

& Resins Nanotechnology Predictive Modeling

Taking the weight out of traditional composites

Fundamental Challenges:

Material discovery and novel processing to improve

specific properties (e.g. strength, toughness, thermal stability)

Incorporation of nanoscale porosity with without tradeoffs in

mechanical properties

Multi-scale modeling of material degradation mechanisms

to minimize overdesign

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Cultivating Breakthrough Structural Fibers

2 µm

Low Density ~1.1 g/cc

High strength & modulus

Porous fibers Nanofibers

Satish Kumar

Georgia Tech

Yuris Dzenis

U. Nebraska

Stephen Cheng

U. Akon

Frank Harris U. Akon

The last major breakthrough in carbon fibers was achieved over 20 years ago….

CNT-doped fibers

Frank Harris

U. Akon

*Successful Tech Transfer

DARPA Structural Fiber Program

and AFRL/RX

*Pending Tech Transfer

To Fiber Industry

Matteo Pasquali

Rice U.

CNT fibers

*Successful Tech Transfer

Teijin Aramids

Multifunctional, high electrical

and thermal conductivities High strength, high

toughness, nanometer

diameter fibers

Improved tensile

strength and modulus

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CNT Fiber

“…high-performance multifunctional carbon nanotube (CNT) fibers that combine the specific strength, stiffness, and thermal conductivity of carbon fibers with the specific electrical conductivity of metals. “ (Science, 11 January 2013: Vol. 339 no. 6116 pp. 182-186.) Technology Transition

AFRL/RX Teijin Aramids

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Improved Fibers

& Resins Nanotechnology

Nanofibers

Yuris Dzenis U. Nebraska

Stephen Cheng U. Akon

Selected as Nature, 365 Days: Images of the Year 2013

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Improved Fibers

& Resins Nanotechnology

Strong, Tough Nanofibers

Yuris Dzenis U. Nebraska

Stephen Cheng U. Akon

Reduction of fiber diameter from 2.8 μm to ∼100 nm results in

simultaneous increases in elastic modulus from 0.36 to 48 GPa,

strength from 15 to 1750 MPa, and toughness from 0.25 to 605 MPa

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Morphology Control of Polymer Films

Improved Fibers

& Resins Nanotechnology Predictive Modeling

Rodney Priestley

Princeton U.

2013 PECASE Award

2011 YIP Award

Target concentration:

5 mg/ml 3 mg/ml 0.2 mg/ml

Matrix Assisted Pulsed Laser Evaporation

(MAPLE)

Innovative materials processing

yields fundamental morphological

insights and improved material

propertiest

Increased thermal stability

Decreased material density

Increased mechanical properties

Control of polymer morphology

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Molecular Modeling of Time-Dependent

Phenomena in Polymer Matrix Composites

- Understand molecular level

response to effects of physical

aging, environment (oxidation,

temperature, etc) and damage

events

- Understand how to translate

molecular level response to

bulk material properties as a

function of time

- Employ this fundamental

understanding to design

hybrid materials for optimum

performance

Epoxy

Graphite

Efficient Approaches to Incorporating

Physical Aging in a Crosslinked Epoxy,

Odegard, Michigan Tech Univ.

Fracture Parameters from

Atomistic to Micro, Brietzman, et.al,

AFRL/RX

EPON-862

DETDA

Time & Temperature

Dependent Debonding in

Composites, Roy, et,al, Univ.

Alabama

Modeling Elastic & Failure

Behavior, Mukhopadhyay, et.al,

Wright State U.

Sharmila Mukhopadhyay

Wright State U.

Greg Odegard

Michigan Tech Samit Roy

U. Alabama Jim Moller

Miami U. Rajiv Berry

AFRL/RX Tim Breitzman

AFRL/RX

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Nanostructured Hybrid Materials

Improved Fibers

& Resins Nanotechnology Predictive Modeling

Bottom-up materials design, incorporating what is

needed, where it is needed for optimized performance

Novel nanoscale constituents and hybrid

materials with unique, tailorable properties

Fundamental Challenges:

Synthesis, characterization, and modeling of novel 2D

and 3D nanoscale heterostructures

Translation of nanoscale properties to the macroscale

Understanding hybrid material interfaces/interphases and

improving interfacial coupling for enhanced properties

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Translating the revolutionary properties of nanostructured

materials to macroscale load-bearing structures • Signed Memorandum of Agreement with NASA LaRC

• Nanotube Assemblages for Structures Workshop

• Established working group to develop coordinated interagency

roadmap for structural nanomaterials

Nanomaterials for Aerospace Structures

Fundamental Challenge: Nano to Macro

Scaling of Mechanical Properties

1000x stronger than Al

50x stiffer than Al

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1D Carbon

Nanotubes

2D Graphene

Nanostructured Carbon

0D Fullerene

3D

?

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Overarching Scientific Challenges

• Covalent junctions between building blocks leading to 3D networks

• Systematic characterization/modeling of the junctions and properties

• Development of scalable growth processes for 3D nanostructured solids

• Structure-property correlations of mechanical and transport properties

Potential Payoffs

• Translation of exceptional 1D and 2D properties of tubes and sheets to 3D

• High surface area for energy storage and conversion devices

• Orthogonal transport of phonons for thermal management

• Mechanical reinforcement

MURI 11: Nanofabrication of

3D Nanotube Architectures

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Establishing Covalent Nanotube Connectivity

Irradiation-induced Crosslinking

Interconnected CNT bundles

(Yakobson - Theory)

Mauricio Terrones

Penn State U.

Richard Liang

Florida State U.

Boris Yacobson

Rice U.

Metallic-induced Nanowelding

(Terrones)

Ben Wang

Georgia Tech

Electron beam Consolidation

(Wang & Liang)

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James Tour

Rice U.

Boris Yakobson

Rice U.

Towers of nanotubes sprout from graphene (Futurity, Sci. and Technology, Nov. 27, 2012.)

(Nature Communications, 3:1225 doi: 10.1038/2234 (2012))

CNT/Graphene Networks

Model prediction

7-atom rings at the graphene-nanotube

junction creates a seamless conductor

Pulickel Ajayan

Rice U.

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3D Graphene/Nanotube

Multifunctional Porous Networks

Tour, Ajayan, Choi, et al. ACS Nano (2013).

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Multifunctional Materials

Improved Fibers

& Resins Nanotechnology Predictive Modeling

Reducing system weight by designing materials

that do more…. coupling structure and function

Fundamental Challenges:

Materials discovery to engender improved multifunctionality

(e.g., radiation resistance, electrical & thermal conductivity)

into load-bearing materials

Materials and methods for enabling active, adaptive,

tunable, efficient performance

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NSF (ENG)/AFOSR MOU for Co-Sponsoring Emerging

Frontiers in Research and Innovation (EFRI) Program

Solicitations - ”…will cooperate to leverage their

complementary missions of fostering basic research.”

Signed August 2011

Interagency Collaboration

ODISSEI: Origami Design for Integration of Self-assembling

Systems for Engineering Innovation

Goal: advance understanding of folding and unfolding of materials

structures across scales for design of engineered systems

Outcome: Jointly reviewed and funded 13 grants plus

an AFRL labtask totaling approx. $26.5M

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Joint RX, RQ Labtask Adaptive Origami for Efficiently Folded Structures

STRUCTURES MECHANISMS

Aeronautics Aerospace

Light and strong Compact, repeated pattern

Optics, Sensors, Energy Harvesting, Bio Research Team

http://www.origami-resource-center.com/origami-science.html

Origami Honeycomb

Shock absorbing

structures

Self folding sheet

Ultrathin, High-

Resolution Origami

Lens

Deployable Solar sails, Antennas

Solar origami

Expandable stents

Wing folding

James Joo Greg Reich Rich Vaia Tim White Loon-Seng Tan

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Summary

Program supports transformative research targeting advanced materials

that enable significant reductions in the weight of aerospace platforms and

systems with enhancements in performance and function

Current Research Thrusts

- Structural lightweighting

- Nanostructured hybrid materials

- Multifunctional materials

Increased emphasis on forging collaborative teams to address

broad-base challenges

Increased leveraging of tri-service and interagency collaborative

opportunities

Increased emphasis on interagency 1um

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104

Markus

Buehler

MIT

Ashlie Martini

UC Merced

Robert Moon

Forrest Products

Lab

Acknowledgements

Brandon Arritt

AFRL/RV

Ryan Justice

AFRL/RX

Benji Marayama

AFRL/RX

Chris Muratore

AFRL/RX

Rajesh Naik

AFRL/RX

Sharmila

Mukhopadhyay

Wright State U.

Satish Kumar

Georgia Tech Greg Odegard

Michigan Tech

Soumya Patnaik

AFRL/RX

Ajit Roy

AFRL/RX

Marilyn Minus

Northeastern U.

Yuris Dzenis

U. Nebraska

Stephen Cheng

U. Akon

Frank Harris

U. Akon

Samit Roy

U. Alabama

Alex Zettyl

UC Berkeley

Ben Wang

Georgia Tech

Cheol Park

Natl Inst Aerospace

Richard Liang

Florida State U.

Jeff Youngblood

Purdue U.

Changhong Ke

Binghamton U.

Mesfin Tsige

U. Akron

Rodney Priestley

Princeton U.

Henry Sodano

U. Florida

Micah Green

Texas Tech U.

Philip Bradford

NC State U.

Yuntian Zhu

NC State U.

Pulickel Ajayan

Rice U.

Liming Dai

Case Western

Reserve U.

Changhong Ke

Binghamton U

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Cultivating Breakthrough Structural Fibers

2 µm

Low Density ~1.1 g/cc

High strength & modulus

Porous fibers Nanofibers

Satish Kumar

Georgia Tech

Yuris Dzenis

U. Nebraska

Stephen Cheng

U. Akon

Frank Harris U. Akon

The last major breakthrough in carbon fibers was achieved over 20 years ago….

CNT-doped fibers

Frank Harris

U. Akon

*Successful Tech Transfer

DARPA Structural Fiber Program

and AFRL/RX

*Pending Tech Transfer

To Fiber Industry

Matteo Pasquali

Rice U.

CNT fibers

*Successful Tech Transfer

Teijin Aramids

Multifunctional, high electrical

and thermal conductivities High strength, high

toughness, nanometer

diameter fibers

Improved tensile

strength and modulus

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CNT/Polyacrylonitrile (PAN) Fibers

Improved Processing via Gel and Bi-component spinning

Higher molecular weight and purity monomers

Templating with Carbon Nanotubes

• High degree of structural perfection

• CNT fibril reinforcement

• Smaller diameter fibers

• Enhanced mechanical properties:

64% increase in tensile strength

49% increase in modulus

PAN PAN/CNT

Technology Transition AFRL/RX

DARPA Advanced Structural Fiber Program

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Improved Fibers

& Resins Nanotechnology Predictive Modeling

Prof. Rodney Priestley

Princeton U.

2013 PECASE Award

2011 YIP Award

NSF CAREER Award

Howard Wentz

Junior Faculty Award,

Princeton U.

International

Quadrant Award

Inorganic/Organic Hybrids

Reinhold Dauskardt

Stanford U.

spin coat

polymers ΔT

polymer

infiltration Substrate

polymer/solvent

Achieved dramatically improved toughening (up to 5x original matrix toughness)

Translates proven toughening strategies for macro-scale composites to the nanoscale

Toughening effect is the result of the collective energy dissipation of many individual polymer chains

synergetic toughening mechanisms

blunting

molecular

bridging plastic

zone

molecular deformation under confinement

103

104

105

106

107

0

2

4

6

8

10

12

Co

hesiv

e F

ractu

re E

ne

rgy,

Gc (

J/m

2)

Molecular Weight (Da)

bulk-like confined “hyper”

confined

unfilled

marked

toughening

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Probing the Interface for

Self-Strengthening Mechanisms

Mauricio Terrones, PSU

Richard Liang, FSU

Bone

Zhang et al., 1993

Bones and trees actively

reinforce themselves in

response to cyclic loading

Can we mimic this response in synthetic

materials? Jun Lou,

Rice U.

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Interagency Collaboration

AFOSR BRI

2D Materials

Beyond Graphene

NSF EFRI

2 Dimensional Atomic-

layer Research and

Engineering

(2-DARE)

• 2D heterostructures, free of epitaxial strains promise to yield an array of

unique properties

• Graphene – conductor, 2D BN – insulator, 2D MoS2 – semiconductor,

2D NbSe2 – superconductor

• Bandgap of MoS2 transitions from being indirect in bulk to direct in 2D

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Engineering Application: Solar Origami High Efficiency Foldable Solar Blankets

10-15X more solar power – same carry size

Army: Rucksack Enhanced Portable

Power System (REPPS) • Foldable solar panel (CIGS) and

power control electronics

• 55 W at peak illumination

• 32” x 55” unfolded (12” x 12” folded)

• Solar origami unfolds 2-5X larger

than traditional folded design

• GaAs devices > 3X efficiency of

CIGS or amorphous Si

• Could increase REPPS output

from 55 W to ~500W

CIGS State-of-the-Art

Concept: Miura-ori Foldable

Solar Blanket

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Marilyn Minus,

Northeastern U.

Studying Interfacial Interactions and

Ultimate Composite Properties

10 µm

Burn out of a PAN-rich

region leaving behind void

5 µm

Only small voids are

present in the fiber

Molecular dynamic studies show an increase in PAN-SWNT

interactions as the SWNT dispersion quality and PAN chain

confinement increases

(a & b) PAN chains on

SWNT surfaces (poor

dispersion) – PAN-PAN

interactions dominate

(c & d) PAN chains

confined between SWNT

(most prevalent in

composites exhibiting

good dispersion) – PAN-

SWNT interactions

dominate

E: 12 GPa

σ: 0.4 GPa

E: 32 GPa

σ: 1.3 GPa