Application of Composites in Aircraft Industries

8/8/2019 Application of Composites in Aircraft Industries

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Fuel Economy

Light weight

High Performance

More Payload

Low cost


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Different composites mainly used in Aerospace

1.Glass / Epoxy, Kevlar/ Epoxy

2.Carbon / Epoxy

3.Boron / Epoxy


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These are used in storage room doors, landing gear

trap doors, karmans, radomes, front cauls, leading edges,

floors, and passenger compartments.

Pluses:Very good fatigue resistance

Minuses:

High elastic elongation

Maximum operating temperature around 800C

Non conducting material


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Pluses:

High rupture resistance

Very good fatigue strengthVery good heat and electricity conductor

High operating temperature (limited by the resin)

No dilatation until 6000C

Smaller specific mass than that of glass/epoxy

Minuses:

More delicate fabrication

Impact resistance two or three times less than that of glass/epoxy

Material sensitive to lightning

This is used in wing box,

horizontal stabilizers, fuselage,

ailerons, wings, spoilers (air brakes) vertical stabilizers.


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This is used for vertical stabilizer boxes and horizontalstabilizer boxes.

Pluses:

High rupture resistance

High rigidityVery good compatibility with epoxy resins

Good fatigue resistance

Minuses:

Higher density than previous compositesDelicate fabrication and forming

High cost


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1. Sandwich Design

Sandwich with transverse honeycomb:


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Sandwich panels-- low density, honeycomb core-- benefit: light weight, large bending stiffness

honeycomb

adhesive layerface sheet

Adapted from Fig. 16.18,

Callister 7e. (Fig. 16.18 is

from Engineered Materials

Handbook, Vol. 1, Composites, ASM International, Materials Park, OH, 1987.)


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0 2 4 6 8

Carbon / Epoxy

Boron / Epoxy

Glass / Epoxy

Titanium

Steel

Aluminium

Tensile Strenght / Density (in X 10**6)


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0 5 10 15

Carbon / Epoxy

Boron / Epoxy

Glass / Epoxy

Titanium

Steel

Aluminium

Elastic Modulus / Density (in X 10**8)


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Payload 68 tons, range 8300 km.

This study gives the following significant results:-

For an aircraft made using conventional metallic construction:

Total mass at take-off: 243 tons

Mass of t

he structure: 175 tons

For an aircraft made using maximum composite construction:

Total mass at take-off: 164 tons

Mass of the structure: 96 tons.

A reduction of1 kg mass leads to the reduction of fuel consumption

of around 120 liters per year.


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Traditional

Future

Innovative

CONVENTIONAL COMPOSITE

High strength

Brittle

Lower weight

NANOCOMPOSITE

High strength

Not Brittle

Lowest weight

METAL ALLOYS

High strength

High weight


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31

21

10

29

0

10

20

30

40

Alluminum Titanimu Composites other

49

32

2

29

0

20

40

60


16

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24 21

0

20

40

60



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The Boeing 787 has 50% of its primary structure made of composites.


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Redesign of C-17 Horizontal Stabilizer

Historically constructed of Aluminum

Redesigned using PMCs resulted in:20% Reduction in weight

69% Reduction in tooling

81% Reduction in fasteners

48% Net cost reduction

Reduction in fasteners reduces sources of corrosion


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First of its kind to use composite structures for

wings, fuselage, and nose cone.

Increased resistance to hoop stress in the fuselage

allowing the cabin pressure increases.

Lower altitude pressure = Increased comfort

for passengers.


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Increased fuselage

strength allows for the

largest windows

available on a

commercial

aircraft, which benefits

passengers experience.


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With all these great benefits why are

aircraft manufactures not usingcomposites more?


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If its not broke, dont fix it

Metals (especially Aluminum) have been tested

extensively and have detailed models for their

behavior.

Airlines financial problems reduce the amount

of money available forR&D


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Lightning Strikes

Ice on Wings

Water penetration

Micro cracking

Extreme temperatures


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Modeling of PMCs requires extensive

knowledge of:Matrix Polymer

Fiber inclusions

Fiber Lay-up

In some cases PMCs are not used because

the over designed part does not result in any

design advantage


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Nanocomposites

Carbon Nanotubes

Benefits:

High Yield Strength / Elastic Modulus

High Electrical Conductivity

Low Co-efficient Thermal Expansion

Polymer CNT composites can have the potential to vastly

increases in mechanical properties at very low weight

percentages.


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Due to the small size of CNTs, (~1nm in diameter)

High surface area of interaction between CNT and polymer

creates strong bonds between inclusion and polymer

Inclusion at small weight percentages gives no change inopacity.

Allows for clear sections of the fuselage, without

having to cut sections for windows, eliminating an areaof the aircraft with high stress concentrations


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Production Primary and Secondary structure for the Boeing 777, an

example of1990s commercial application of composites.


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In environmental conditions differing greatlyfrom the ambient the inherently complex

material response of PMCs over time and the

resulting evolution of their structural andfunctional properties have limited their

effectiveness.

Challenges exist in modeling the complexities

of PMCs and testing and quality assurance

costs can limit the benefit of using a composite


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Application of Composites in Aircraft Industries

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