2. OUTLINE
Background
University of New Orleans (UNO) work relates to developing three
functional properties in composite materials: (1) Energy
absorption (2) blast protection and (3) durability
UNO applied nanotechnology-based solutions through the
utilization of nanomaterials that dissipate a substantial fraction of
the shock/blast energy that is received
We analyzed the mechanisms
Experiments with nano-particle filled composites in linear impact
(Hopkinson Bar)
Experimented with CNT reinforced damping (Vibration)
Applied holography and laser vibrometry for experimental records
We have proven nanoparticle-based energy absorption
technology
Energy absorption was achieved by providing large energy sink
by sources for friction and slip-stick motion at interfaces of matrix
and nanoparticle.
4. WHAT US NAVY WANTS
FOR THE SHIPS?
Lighter
Stronger
Faster
The above are the three mantras
for the Navy’s R&D search for
new materials
5. NEW MATEIALS SHOULD
ENABLE THE NAVY TO
HAVE SHIPS
Quickly deployable
Carry Larger Payloads
Survive threats in high seas
These would be possible if materials with
specific property improvements are introduced
6. Navy’s new materials of the
future
NANO-COMPOSITES
In all their varieties as
Smart
Adaptive
Multifuctional
Etc
Etc
8. NAVY IS CHANGING
NEW TECHNOLOGIES FOR NAVY
ALL VARIETIES OF COMPOSITES Smart, Adaptive, Nano,
Multifunctional, Graded
FRICTION STIR WELDING Avoids HAZ
NEW HULL DESIGNS Advanced composite Double Hull
(1998)
Double M Hull (2004)
NEW JOINT DESIGNS Composite to Metal
9. Technology show case
Swedish all-composite STEALTH ship – First in the world
Max length possible with today’s technology : 209 ft
Ships longer than 400 ft can not be built with composites
Because of lower stiffness
New ship double hull concept
New hybrid hull concept
The bow and stern made of
Composite, the mid part stainless steel
Metal-composite jointing
is in issue
10. TECHNICAL DISCUSSIONS
-BASICS-
SOLID IMPACT ON A MULTI-LAYERED SOLID MEDIA
1 dimensional problem :
FORCE F = PA V v
IMPACTOR VELOCITY =V
IMPACT ENERGY = 0.5MV2 Particle velocity =v
S
Stress Pulse Energy = cv
(unidirectional stress wave propagation theory)
IF IMPACTOR IS CYLINDRICAL SOLID where:
AND GAS PROPELLED, THEN = Density
IMPACT ENERGY = PAS v = particle velocity
WHERE c = stress wave velocity = (E/ )0.5
P = PRESSURE E = Young’s modulus
A = AREA
F2
Note: Transformation of energy from low amplitude F 2 >> F1
force to high amplitude force to cause damage t 2 << t 1
IMPULSE = F1 t 1 = F2 t 2
F1
t t
t1 t2
11. IMPACT ---BASICS
F2
Note: Transformation of energy from low amplitude F 2 >> F1
force to high amplitude force to cause damage t 2 << t 1
IMPULSE = F1 t 1 = F2 t 2
F1
t t
t1 t2
ENERGY OF THE IMPACTOR = (1/2)MV2
ENERGY OF STRESS WAVE = [A/( C)]
(1/2)MV2 = [A/( C)]
The trick to make a structure to survive impact is to make the high
amplitude F2 (stress) transform to low amplitude F1 so that the
material’s strength is not exceeded. Modifying materials by using
nanotechnology achieves it by dispersing the stress wave
amplitude very rapidly
12. Dutta-Tech
Multiple Impedance Pressure Bar (MIPB)
MULTILAYER WAVE PROPAGATION – Increased Number
Of Interfaces Cause Decrease in Propagating Stress Amplitude
Impedance Z = ρc/g
Steel
PC AL brass steel Strike
r
Light Gas
Materials of different impedences Pressure
SG SG SG SG
SG = Strain Gage
14. Dutta-Tech
DUTTA HYPOTHESIS
FOR IMPEDANCE GRADIENT WHICH CONSIDERS
INFINITE NUMBER OF LAYERS
Interface
Damage
Multiple Plate
Impedance
Mismatched
Barrier/Armor
Impedance
graded No Interfaces
Barrier/Armor
15. Dutta-Tech Impedance Effect Processing Model from
Hopkinson Bar Test Data
Energy content of a stress wave pulse:
Evaluate Attenuation by comparing wave amplitude Ac t
∫ σ dt
2
And wave energy in incident and in transmitted bar after
U ( Energy ) = 0
E
The wave has passed through the designed IMG material
Where A is the rod area, c is the wave velocity
E is the Young’s modulus, sigma is stress, and t is time
INCIDENT WAVE AMPLITUDE INCIDENT WAVE ENERGY
Stress waveforms in incident bar - test MIX-5B-Direct Energy: stress square- t curve MIX 5B-Direct
50000000
s )
s m s u re (p i^2
6000
4000 40000000
Stress (psi)
2000 S(in) 30000000
ig a q a
0
-2000 S(in) 20000000
-4000 10000000
-6000
-8000 0
0 2000 4000 6000 8000 10000 12000 14000 -10000000 0 2000 4000 6000 8000 10000 12000 14000
Tim (Seconds)
e tim (seconds)
e
TRANSMITTED WAVE AMPLITUDE TRANSMITTED WAVE ENERGY
Transmitted stress wave Energy: stress square - t curve Mix 5B-Direct
MIX 5B
Sigm square (psi^2)
50000000
6000 40000000
Stress (psi)
4000
2000 30000000
0
-2000 Sin (t) 20000000
a
-4000 10000000
-6000
-8000 0
0 2000 4000 6000 8000 10000 12000 14000 -10000000 0 2000 4000 6000 8000 10000 12000 14000
Tim (seconds)
e Tim (Seconds)
e
Amplitude Attenuation : S(t)/S(in) = 53% Energy Attenuation : S(t)/S(in) = 28%
17. WHY NANO-COMPOSITES?
Look at the Problems of Traditional Ship CarbonSteels:
Corrosion
Thermal and Electromagnetic Signature
Construction by framing and sheathing and
welding numerous parts with 100 yrs old designs
Labor intensive
Numerous Heat Affected Zones (HAZ) stress concentration
HAZ’s readily corrdes and fail in fatigue
Extensive coating is required
Result: Higher building and maintenance costs
18. WHY NANO-COMPOSITES?
Advantages with NANO-Composites:
• Higher strength-to-weight ratio
• Lower Magnetic Signature
• Lower Acoustic Signature
• Lower Hydrodynamic Signature
• Lower Thermal Signature
• Lower Radar Signature
• Lower maintenance cost
• Parts consolidation in fabrication
• Fatigue resistance and durable
AND NOW NANO WILL MAKE
THE MATERIALS MORE BLAST
AND SHOCK RESISTANT
•
20. OBJECTIVE
Multi-walled carbon nanotube (MWCNT) in a
polymer is believed to modify the energy absorbing
haracteristics of the resulting nano polymer
composites.
Our objective here is to find out the efffects of
MWCNT contents on the dynamic mechanical
properties, including energy absorption
characteristics of the resulting Polymer
Nano-composites.
21. Materials
The materials were Fabricated at Univ of Mississippi
Fabrication
1. Mix different percentages of MWCNT in Nylon 6,6
2. Mold into a panel
3. Cure
4. Cut to lengths
25. Governing Equations
t
Avg strain = ∫ C the specimen =
u in ε dt
1 0 1
0
t
u 2 = ∫ C0ε 2 dt
t
0
u1 = ∫ C0ε1dt
Avg stress in the specimen =
0
Avg strain rate in the specimen =
Energy Absorbed =
L = Specimen length
31. CONCLUSIONS
MWCNT Nylon composites are extremely tough.
They did not completely fracture under dynamic peak
stress of 170 MPa. Internal Damage Predicted from
permanent dimensional change.
Modes of failure need to be confirmed by SEM
MWCNT modified strength, stiffness and energy
absorption. Only after smaller addition the properties
improved significantly (20% approx). The reasons are
being investigated.
Nylon is thermoplastic and energy absorbent.
Additional work needed with thermoset composites
33. Nano-particle-reinforced energy
absorption:
It involves placement of numerous nano
particles
During impact nanoparticles interact
with internal matrix and with one
another and thus dissipate energy
through momentum transfer and friction
34. Parameters controlling energy
absorption in these materials
Particle size
Dispersion in matrix
Shape
Density
Texture
Coefficient of restitution
Coefficient of friction
Surface area and conditions
Free space around the particles
Strain rate
35. Microstructure of filled composite materials
Example of a typical syntactic foam composite material with a relatively
low volume fill of micro-spheres. The sphere “ringed” is approximately
50µm
µ
36. Mechanisms of shock and blast
energy dissipation
syntactic homogenous material
foam
composite
material K and G
representative hydrostatic shear load
volume pressure load
Principle of homogenisation method for syntactic
foam composite materials
38. Properties of interphase layer Effective
thickness of
interphase
layer
Approaches to control the
interphase layer
Chemical dispersant /
surfactant to achieve
dispersion and effective
thickness of the layer
Electrostatic ultrasound 30nm thickness of
interphase layer
50-80 vol.%
treatment concentration of
nanoparticles
High shear force mixing
to prevent agglomeration
100nm thickness
of nanoparticulates of interphase
layer
10-30 vol.%
concentration of
nanoparticles
41. Composite Materials,
Experimental
Samples manufactured manually by meltmixing
nanotubes and polymer by extrusion process
Investigated the effects of different orientations
of carbon nanotubes (CNT)
Applied multiple stress rates
Viewed results by holography technique
High strain rate was produced by Bruel and Kjaer
(B&K) vibration system
Energy absorption capacity was measured by
damping capacity measurements
42. Nanotube-FRP Experimental
(Contd)
CNT orientations were controlled by extrusion rate
We measured : frequencies, mode shapes, and damping at each mode by
the B&K laser vibrometry
Computer
System
Laser
vibrometer
Electro- Clamped
dynamic Sample
exciter
43. Density, kg/m3 (Temp.=25C)
0
200
400
600
800
1000
1200
1400
ep IP
40 ox 29
20 w y 0
w t.% V
er
1125
t.% ifl
Si e
30 N O
w i-c ,5 x Pure
oa 00 epoxy
1045
t.%
te µm
20 N d,
i-c 12
w o 0µ 1136
t.% ate
m
40 VS d, 1
866
w 20
t.% 550 µm
VS 0, 1
828
20 55 00
µm
w 00
,1
t.%
772
00
40 D
2 w 32 µm
w ,1
Microscale
t.% t.% 20
Ex D3 µ
pa 2, 1 m
nc 20
el
5 , 1 µm
w
740 726 740
t.% 0-4
0µ
10 Si
O m
w
t.%
300
1-
5µ
2.
5
Si
O m
w 1-
1150
t.% 5µ
5 Si m
w C
1210
t.% 50
Mesoscale
2. nm
5 Si
C
w
t.% 50
1080
nm
5 Si
O
w
1060
t.% 15
2.
5 Si nm
O
w
t.% 15
nm
5 Si
O
w
1030 1010
t.% 10
2
w Si nm
O
t.% 7 w
1050
t.% 10
2 m nm
Nanoscale
w es Si
O
t.% oS
990
m iO 10
2 ,8 nm
w es
t.% oS nm
930
m iO po
es ,4 r
oA nm e
790
lS po
2 i, re
w 8n
t.% m
730
5 C po
w N re
t.% T
10
750
C 0n
Density (weight) of foam composites
N m
T
10
730
0n
m
690
Carbon
Nanotubes
45. Damping prediction
9
10
Modulus (Pa) 8
10
7
10
6
10
0.6 A + glas s
____ SWCNT + polymer A
A + poly
B + glas s + poly
Loss factor
- - - MWCNT + polymer A
0.4 CNT+ polymer B B + poly
- - CNT+ polymer A +
ceramics
0.2
0
0 20 40 60 80 100 120
Tem perature (° C)
Mechanical and damping and Properties at 10 Hz: 5wt% CNT-reinforced balloon-
BOUNDARY MESHLESS
based foams. The peak damping occurs around 100°C for CNT-reinforced
FORMULATION FOR °
polymer balloon-basedOF SOLIDS
DEFORMATION syntactic 45
48. Nanotube-FRP Experimental
(Contd)
Resonant frequency was determined from the peaks of the frequency
response curves
Each mode shape was the characteristic of the specific NT-FRP
A finite element model was used to determine displacements and stresses
for each orientation of the CNT with respect to loading direction.
Vibration Vibration
Load Load
(a) (b) (c)
Nanoparticle orientation: (a) CNT along the load direction P, (b) chaotic distribution
of CNT, and (c) perpendicular CNT to the load direction.
49. Nanotube-FRP Experimental
(Contd)
Modes of vibration of the NT-FRP samples by holography:
a b c
d e f
CNT-reinforced samples, viewed by holography and in color
computer imaging for different CNT orientations:
(a) CNT along the load direction P, (b) chaotic distribution of CNT,
and (c) perpendicular CNT to the load direction
50. Nanotube-FRP Experimental
Results
Frequency was varied from 200 to 4000 Hz
Twelve natural frequencies were identified
Signals were noisy below 400 Hz
Single matrix had better coherence than the CNT-FRP’s
Variation between tests and finite element prediction of frequencies was within 10%
Clamping conditions influence variations
Resonance Frequencies Obtained by Laser Vibrometry at Room Temperature
ω, along CNT- ω, perpendicular
ω, Polymer
Mode # reinforced %, Diff. CNT-reinforced %, Diff.
matrix (Hz)
polymer (Hz) polymer (Hz)
1 186 112 39,8% 132 29.0%
2 506 254 49.8% 411 18.8%
3 860 544 36.7% 546 36.5%
4 1206 856 29.0% 974 19.2%
5 1,658 1,211 27,0% 1,346 18.8%
6 1,924 1,612 16.2% 1,574 18.2%
7 2,504 2,016 19.5% 2,182 12.9%
8 2,934 2,123 27,6% 2,176 25.8%
9 3,624 3,086 15.1% 3,560 1.8%
10 3,918 3,134 20.0% 3,545 9.5%
51. ANALYSIS- Interphase layer model
:
Assumption The dissipated energy, via interfacial movement of
nanotube and polymeric material, is linked with the local cohesion and
adhesion phenomena between the filler/matrix interface.
Consider the equivalent shear force and the differential displacement
between tube and matrix (after Koratkar et al 2002, and Odegard
2004)
η = Loss factor
Udiss = Energy Dissipation
r = radius of nanotube =10-100nm
l2 = length of nanotube
52. ANALYSIS- Interphase layer model
(Contd)
Strain between nanotube and matrix material ( 2 ):
Where
R = radius of the representative volume V
G = Shear modulus
E eq = Equivalent modulus of nanotube = 2(l/t)Eg
And
53. ANALYSIS- Interphase layer model
(Contd)
Stress in composite materials is associated with
energy dissipation and is given by:
56. Sample preparation for
nanoindentation
Typical microtomed
nanocomposite samples
mounted on magnetic steel
disks to hold the sample
magnetically.
Polishing of the microtomed
section of sample is not
desireable due to a risk of
particle failure.
Notes to the rightside figure.
Steel disk diameter 15mm.
Heating stage used on the
NanoIndenter. Samples are
thin to control the surface
temperature.
Samples are held by springs.
Size of heated plate approx.
57. Nanoindentation of multilayered and
nanomaterials at interphase
Several samples mounted on standard stage;
Area 15x15cm; height 0cm - 3cm; weight <10kg
58. Nanoindentation at statics
Typical indentation load-displacement
curves for fibre, matrix and the transition Variation of elastic modulus across the
region at a maximum indentation depth of matrix-interphase-fibre
60 nm
Source: Jang-Kyo Kim, Man-Lung Sham. Composites, part A 32, 2001. 607 – 618
59. Surface topography of composite
materials
SiO sphere-filled composite
material sample; polymer
matrix (epoxy) with dispersed
inclusions (lightweight and
stiff hollow SiO spheres) on
Surface Topography at the filler- left corner, improving blast
matrix interphase point, showing a resistance of matrix.
step change in mechanical
properties at the interphase;
62. Prediction of Energy Dissipation at Impact
Stress
Impact stress of centrally notched specimen was simulated by MSC.Visual Dytran/LS.Dyna for
Windows XP.
63. Benefits of filled nanocomposites
1.Contains organically-treated, fillers that disperses evenly
throughout resin.
2.Reinforcement efficiency is achieved at low concentrations (3-
5%) that has a small cost in terms of specific gravity.
3.Stiffness comparable to a 20-30% load of a standard mineral
filled compound.
4.Vibration damping and heat resistance considerably increased
in nanocomposites.
5.Lower loading levels (2-8 wt.%) help maintain resin
transparency.
6.Available for injection molding, extrusion (sheet or film), and
blow molding.
7.Other benefits of nanocomposite include: lower gas
permeability, good surface appearance, dimensional stability,
and lower heat release.
64. Conclusions and general
remarks
NT-FRP show a great promise of energy absorption as clear from
the study of their damping characteristics
The nano structure in which the polymers tend to form large-
diameter helices around NT favors strong matrix bond
Depending on orientations the NT increases or decreases the
bond strength, fracture strength or damping by 10-20%
More work is needed to characterize the effects of SWNT, MWNT,
Fullerene, BN, or SiC nanotubes, dispersion and orientation
effects,
Multiscale vibration damping modeling needs to be refined
Both computational and experimental benchmarks need to be
improved
65. Refereed Journal Articles published with
respect to this work
1. M. Kireitseu, G. Tomlinson, D. Hui, L. Bochkareva. Dynamics and Vibration Damping
Behavior of Advanced Meso/Nanoparticle-Reinforced Composites. Journal of Mechanics of
Advanced Materials and Structures, 14(8), 2007, 603-617.
2. M. Kireitseu, D. Hui, G. Tomlinson. Advanced shock-resistant and vibration damping
properties of nanoparticles-reinforced composite material, Jrnl. of Composites Part B 39(1),
2008, 128-138.
3. Lurie S, Hui D, Kireitseu M V, Zubov V, Tomlinson G R, Bochkareva L, Williams R A.
“Computational Mechanics Modelling of Nanoparticle-Reinforced Composite Materials across
the Length Scales”. Int. Journal of Computational Sc. and Engineering, 2 (3-4), 2006, pp.
228-241.
4. M. Kireitseu, V. Kompiš, D. Hui, G. Tomlinson, L. Bochkareva, S. Lurie. Modelling of Strength
of Nanoparticle-Reinforced Materials and their Applications. Jrnl. of Science & Military, 2 (1),
2006, 1-6.
5. D. Hui, M. Kireitseu, G.R. Tomlinson, V. Kompis. Advanced Design Concepts and Modelling
of Composite Materials in Emerging Applications. Advances in Science and Technology, 50,
2006, pp. 124-130.
6. M.V. Kireitseu, D. Hui, K.T. Lau, Viscoelastic behaviour and vibration damping properties of
epoxy based composite filled with coiled carbon nanotubes, Journal of Nanomaterials,
Hundawei Publ. House (submitted, August 2008)
