1-6.

Advantages of Composite Materials

l 1) Can achieve a uinque combination of properties.
ex) Epoxy resin E →4 GPa good elastic modulus
ρ→ 1.2 g/cm3 low density
Graphite Fiber E →1000GPa excellent elastic modulus

ρ→ 2.6g/cm3 low density

Graphite/Epoxy Resin E → 306GPa great elastic modulus

ρ→ 1.5g/cm3 low density
l2) The properties can be controlled over a wide range.
ex) Coefficient of Thermal Expansion of SiC/Al Composite
Al: CTE → 24×10-6K-1
SiC: CTE → 4×10-6K-1
l 3) Can achieve properties not attainable by either of the two
component alone.
ex) Thermal Conductivity of porous composite < Thermal cond. of each
component
Microtherm : Kind of microporous heat insulation
material
Ingredients : amorphous silica(50~90%), titanium oxide(10~50%), glass
filaments(1~12%), aluminum oxide(1~25%)
Characteristics :
- Extraordinarily low thermal conductivity by optimization of the formulation to
resist all forms of heat transfer (conduction, convection, radiation)
- Void volume is 90% of the total volume
- Void size are incredibly small so collisions between gas molecules are almost
entirely eliminated.

< Microstructure>
<Thermal conductivity> <Application>
1-6. Advantages of Composite Materials
l 4)
Ø Weight : light wt, uniform wt distribution.
Ø Strength & stiffness : high value, directional property.
Ø Dimensions : large parts, special geometry.
Ø Surface properties : corrosion resistant, weather
resistant, tailored surface finish.
Ø Thermal properties : low thermal conductivity, low coeff.
of thermal expansion.
Ø Electric properties : non-magnetic, radar transparency,
high dielectric strength.
 Disadvantages of Composites
l High cost of raw materials and fabrication of composites
l Mechanical characterization of a composite structure is more complex
than a metal structure
l Repair of composites is not a simple process compared to that for
metals
l Composites do not have a high combination of strength and fracture
toughness compared to metals
l Composites do not necessarily give higher performance in all the
properties used for material selection: strength, toughness, formability,
joinability, corrosion resistance, and affordability
l Possible weakness of transverse properties
l Weak matrix and low toughness
l Environmental degradation of matrix
l Difficulty with analysis
Applications of Composites
Applications of Composites
 Composite in aircraft
l Nearly any new aircraft has extensive use of
composites;
Stealth Aircrafts
l Extensive use of carbon fibre composites to
make them undetectable by radars
l The trends in the use of composite materials for US jet fighter

is given below:

l F-15E: 2% (Boron/epoxy in empennage structure)

l F-18E/F: 19% (weight reduction, improve strength, reliability

and maintainability in a carrier environment.)

l F-22: 24% (integrated structures, stealth features with

affordability)

l F- 35, JSF: 42% (integrated blended wing-body structure,

stealth function)
Materials Distribution for the F-18 E/F Aircraft
l The usage of composite in commercial transportation planes
has been significantly increased.

l For example, composites in new launched Boeing 787

(Dreamliner) account for 50 % of the airplane structural weight.
Aluminium will comprise only 12%. On B-787 exterior
surface, the only visible metals are the leading edges and
engine pylons structures.
 •Boeing 787, the
Dreamliner, has gone to
be the world’s major
commercial jet fuselage
to be built of composite

•Although, composites were

previously used in secondary
structures of airplane parts,
this was the first time
composites were used in the
primary structures.
 Composites in Airbus Aircraft
l Airbus A-380, the Giant of sky, is another successful example with the
usage of composite up to 25% as shown in next Fig.

l Airbus was the first manufacturer to make extensive use of composites

on large transport commercial aircraft.

l The A310 was the first production aircraft ever to have a composite

fin box.

l The A320 was the first aircraft to go into production with an all-

composite tail.
l About 13%by weight of the wing of the A340 is made of composite
materials, and the A340/500-600 was the first airliner with a carbon
fibre reinforced plastic (CFRP) keel beam and rear pressure bulkhead.
 Composites in Airbus Aircraft

General structural design criteria for fuselage and tailplane of A380

Major advanced material candidates reviewed for A380
The A380 is the first large commercial aircraft with a centre wing box
produced largely from CFRP representing a weight saving of up to 1.5
tonnes compared with the most advanced aluminium alloy. The A380 also
incorporates the world's largest composite rear fuselage section to date.
Major monolithic CFRP and Thermoplastic applications in A380
Airbus has pioneered the use of CFRP as an alternative to metal due to its
intrinsic benefits. These benefits include strength, low weight, corrosion-
free quality, and superior durability when compared with conventional
aircraft materials.
Major honeycomb applications in A380
l Overall, Airbus is continuing its step-by-step approach to extending the
use of composites on its aircraft, while continuing to consider the benefits
of metallic structures. Composites are not necessarily the best solution for
all parts of the aircraft; the advantages depend on the type of loads and
stresses that the parts are subjected to and their location. As such, Airbus
continues to research and develop advanced ultra-light alloys in parallel
to composites, acknowledging that both material technologies offer
advantages.
 Composite in aircraft

Experts pointed out that the coming 20-30 years will be a

new era for aerospace composite development because
more and more experiences gained in the past decades, the
extensive usage of advanced composite will lead to a
revolution in aviation industrial logistics chain.
 Composite in aircraft
l Firstly, composite structure design uses new design concepts
totally different from metals or traditional materials, which
requires renewable knowledge for designers and design team
reorganized.
l The second is that material production and composite part
fabrication can be completed simultaneously, resulting in a
change in aircraft industrial logistics supply chains, that is, the
traditional logistics chain from the secondary supplier (material
supply) to the primary supplier (part and component supply),
then to aircraft manufacturers will be changed into materials
supplier directly linked to aircraft manufacturer.
l Finally, the totally new composite knowledge will impose a
challenge upon service and maintenance management.
 Composite in aircraft
l The recent progress of advanced composite in
aircraft application is summarized in this Fig.

Expanding usage of composites in aircraft

 Composites in astronautical engineering
l Advanced composites in these engineering applications are
required to have high to ultra-high performance. Weight,
strength and stiffness, and also very high dimensional stability
(even zero thermal expansion of satellite antenna) are extremely
critical.

l Some special and unique requirements must be satisfied to deal

with extreme outer space environmental conditions such as
ozone depletion, UV radiation, and extreme high and low
temperature. The resin matrices are required to have minimized
release rate of low-molecular volatile under space vacuum.
Composites in astronautical engineering

High dimensional
stability with near-
zero coefficient of
thermal expansion
can be achieved
by tailoring fiber
orientation for
space station
composite
component with
frequency
matching with
delicate
instruments Advanced composites in space station
 Composites in astronautical engineering

l Extremely high costs ($1,000 to over $10,000 per pound) are

typical for these products because of the very low production
rates.
l In rocket and missile application, advanced carbon fiber
composites are mostly used to make structural components in
missile warhead, racket launch tube, and solid fuel rocket
motor
l case of strategy missiles such as Trident –II missile，the mostly
used carbon fibers are IM-7 with tensile strength up to 5.3
GPa supplied by Hercules Inc. and T-800 from Torayca giving
tensile strength higher than 5.65 Gpa and modulus of 300 Gpa.
Sporting Goods
Automobile Body Components
 COMPOSITES 2011– looking to the US
industry’s future
l The composites industry in the USA generates
significant economic activity: US$13.7 billion a year
for composites manufacturers and $45.3 billion a year
for impacted suppliers and manufacturers, according
to the ACMA’s 2009 Composites Industry Report.
l US glass reinforced thermoset composites shipments
totalled 2.18 billion lbs in 2009, with the largest
portion (45%) going to construction, the association
reports. The corrosion industry accounted for another
21%, while marine took 15% and transportation used
10%.
l The global composites market is anticipated to
witness good growth and reach approximately $35.1
billion (€25.6 billion) in 2019, with a
CAGR(Compound Annual Growth Rate） of 6.6%
over the next five years.

l The composites market is expected to experience

substantial growth in future with new developments in
various sectors.
 Summary
l Composites are classified according to:
-- the matrix material (CMC, MMC, PMC)
-- the reinforcement geometry (particles, fibers, layers).
l Composites enhance matrix properties:
-- MMC: enhance σy, TS, creep performance
-- CMC: enhance Kc
-- PMC: enhance E, σy, TS, creep performance
l Particulate-reinforced:
-- Elastic modulus can be estimated.
-- Properties are isotropic.
l Fiber-reinforced:
-- Elastic modulus and TS can be estimated along fiber
direction.
-- Properties can be isotropic or anisotropic depending upon
allignment