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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
2
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….
3
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
4
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
5
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
6
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
7
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
8
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
9
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
10
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
11
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
12
Improved Fibers
& Resins Nanotechnology
Nanofibers
Yuris Dzenis U. Nebraska
Stephen Cheng U. Akon
Selected as Nature, 365 Days: Images of the Year 2013
13
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
14
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
15
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
16
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
17
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
18
1D Carbon
Nanotubes
2D Graphene
Nanostructured Carbon
0D Fullerene
3D
?
19
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
20
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)
21
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.
22
3D Graphene/Nanotube
Multifunctional Porous Networks
Tour, Ajayan, Choi, et al. ACS Nano (2013).
23
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
24
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
25
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
26
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
27
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
28
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
29
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
30
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
31
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.
32
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
33
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
34
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
Recommended