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Submitted to, Name: S.Mehatab.Nabi

Dr. Kuruvilla Joseph, ID No: SC11B048

HOD, Dept. of Chemistry

COMPOSITE MATERIALS IN

AEROSPACE APPLICATION

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Contents

1)Introduction

2)Composites

3)Composite materials in aerospace fields

4)Some more applications

5)Conclusion

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Introduction

The need for the highly effective and efficient material which should be

concerned with the ecologyconcerned world of finite resources has led

advanced composites to be one of most important materials in the high

technology revolution in the world today.

A composite material typically consists of relatively strong, stiff fibres

in a tough resin matrix. Wood and bone are natural composite materials:

wood consists of cellulose fibres in a lignin matrix and bone consists of

hydroxyapatite particles in a collagen matrix. Better known man-made

composite materials, used in the aerospace and other industries, are

carbon- and glass-fibre-reinforced plastic which consist of carbon and

glass fibres, both of which are stiff and strong, but brittle, in a polymer

matrix, which is tough but neither particularly stiff nor strong. Very

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simplistically, by combining materials with complementary properties in

this way, a composite material with most or all of the benefits is

obtained with few or none of the weaknesses of the individual

component materials.

The primary benefits that composite components can offer are reduced

weight and assembly simplification. Composite materials are

particularly attractive to aviation and aerospace applications because of

their exceptional strength and stiffness-to-density ratios and superior

physical properties. The increased availability of these light, stiff and

strong materials has made it possible to achieve a number of milestones

in Aerospace technology. Nowadays, a significant amount of advanced

polymer composites is used for military and commercial aircraft and

satellite components. Usage of such materials will reduce fuel

consumption, improve efficiency and reduce direct operating costs of

aircrafts. Composite materials are one such class of materials that play a

significant role in current and future aerospace components.

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Composites

Composite materials, often shortened to composites or called

composition materials, are engineered or naturally occurring materials

made from two or more constituent materials with significantly different

physical or chemical properties which remain separate and distinct at themacroscopic or microscopic scale within the finished structure.

Composite is composed of a matrix as a binder (continuous phase)

containing a filler as reinforcement (discontinuous phase). The matrix

material surrounds and supports the reinforcement materials by

maintaining their relative positions. The reinforcements impart their

special mechanical and physical properties to enhance the matrix

properties. There should be a definite interface between the matrix and

reinforcement, usually of zero thickness. The properties of composites

depend upon those of the individual components and on their interfacial

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compatibility. The strength of the composite depends on the amount,

arrangement and type of fiber reinforcement in the resin. These

composite materials are anisotropic in nature.

The composites are classified based on the matrix into:

1) Metal matrix composites

2) Ceramic matrix composites

3) Polymer matrix composites

On the basis of reinforcement, it is classified into:

1) Particle reinforced composites

2) Structural composites

3) Fiber reinforced composites

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Composites in aerospace field

Fiberglass composites

The most extensively used fiber in aerospace field is fiberglass.

Fiberglass consists of glass fibers embedded in a resin matrix. Main

properties which led to its popularity is light weight, high strength and

non metallic properties. In aerospace application, fiberglass composite is

widely used on aircraft parts that do not have to carry heavy loads or

work under good stress. Usually, it always used for interior parts such as

window surrounds and storage compartments, as well as for wing fairing

and wing fixed trailing edge panels.

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Fiberglass was first used widely in the 1950s for boats and

automobiles, and today most cars have fiberglass bumpers covering a

steel frame. Fiberglass was first used in the Boeing 707 passenger jet in

the 1950s, where it comprised about two percent of the structure. By the

1960s, other composite materials became available, in particular boron

fiber and graphite, embedded in epoxy resins. The U.S. Air Force and

U.S. Navy began research into using these materials for aircraft control

surfaces like ailerons and rudders. The first major military production

use of boron fiber was for the horizontal stabilizers on the Navy's F-14

Tomcat interceptor. By 1981, the British Aerospace-McDonnell Douglas

AV-8B Harrier flew with over 25 percent of its structure made of

composite materials.

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Fiberglass

One of the most common grades of fiberglass is E-type. E is

representing for electrical because its chemical composition formulate

an excellent electric insulator. So, it is most favorable application for

small passenger aircraft parts, aircraft interiors and aircrafts secondary

parts such as radomes and rocket motor casings. E-glass provides a high

strength-to-weight ratio, good fatigue resistance, wonderful dielectric

properties, and retention of 50%, tensile to 600F, excellent chemical

corrosion and environmental resistance. Fiberglass being a selected

material in several applications such as corrosion, low volume

production, very large parts, contoured or rounded parts and any parts

required high specific strength. By using fiberglass, the parts can be

modified to obtain the strength and or stiffness as required by tactically

inserting materials and familiarizing the fiber direction. E-glass also the

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most economical fiberglass for composite and provide adequate strength

in almost appliances at a quite low cost.

Carbon fiber composites

Carbon fiber (Graphite fiber) is an extremely strong thin fiber about

0.0050.010 mm in diameter and composed mostly of carbon atoms. It

is produced from the pitch, which is produced as a byproduct during the

cracking process of crude oil. It is known for its excellent tensilestrength, heat resistance and chemical rsistance. Carbon fiber

reinforced plastics (CFRP) are stiffer than fiberglass. Typically, CFRP

has a modulus of the order of three times that of GRP, one and a half

times that of a Kevlar composite and twice that of aluminum alloy. Its

strength is three times that of aluminum alloy, approximately the same

as that of fiberglass, and slightly less than that of Kevlar composites.

Aerospace CFRP does, however, suffer from some disadvantages. It is

a brittle material and therefore does not yield plastically in regions of

high stress concentration. Its strength is reduced by impact damage

which may not be visible and the epoxy resin matrices can absorb

moisture over a long period which reduces its matrix dependent

properties, such as its compressive strength; this effect increases with

increase of temperature.

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(NASA) for use in aircraft parts. Temperatures as high as 1650C are

anticipated for the turbine inlets of a conceptual engine based on

preliminary calculations. In order for materials to withstand such

temperatures, the use of Ceramic Matrix Composites (CMCs) is

required. The use of CMCs in advanced engines will also allow an

increase in the temperature at which the engine can be operated, leading

to increased yield. Although CMCs are promising structural materials,

their applications are limited due to lack of suitable reinforcement

materials, processing difficulties, lifetime and cost.

Spider silk fibers

Spider silk is another promising material for composite material usage.

Spider silk exhibits high ductility, allowing stretching of a fiber up to

140% of its normal length. Spider silk also holds its strength at

temperatures as low as -40C. These properties make spider silk ideal

for use as a fiber material in the production of ductile composite

materials that will retain their strength even at abnormal temperatures.

Ductile composite materials will be beneficial to an aircraft in parts that

will be subject to variable stresses, such as the joining of a wing with the

main fuselage. The increased strength, toughness and ductility of such a

composite will allow greater stresses to be applied to the part or joining

before catastrophic failure occurs.

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Synthetic spider silk based composites will also have the advantage that

their fibers will be biodegradable.

Hybrid composite steel sheets

Another promising material can be stainless steel constructed with

inspiration from composites and nanontech-fibers and plywood. The

sheets of steel are made of same material and is able to handle and tool

exactly the same way as conventional steel. But is some percent lighter

for the same strengths. This is especially valuable for vehicle

manufacturing. Patent pending, Swedish company Lamera is a spinoff

from research within Volvo Industries.

http://www.appropedia.org/File:Araneus_diadematus_underside_2.jpg

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HONEYCOMB USAGE:

Honeycomb structures are natural or man-made structures that have the

geometry of a honeycomb to allow the minimization of the amount of used

material to reach minimal weight and minimal material cost. Honeycomb

shaped structure provides a material with minimal density and relative high

out-of-plane compression properties and out-of-plane shear properties

There are three types of honeycomb structures:

1)Fiber glass 2)aluminum 3)Graphite Honeycomb stuctures.

This is structure of Aluminum Honeycomb structure.

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HELICOPTERS:

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ADVANTAGES AND DISADVATAGES OF COMPOSITES

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Some applications by famous companies

The structural complexity of a Sea King helicopter rotor blade is

considerable. It incorporates CFRP, GRP, stainless steel, a honeycomb

core and foam filling. An additional advantage of the use of composites

for helicopter rotor blades is that the moulding techniques employed

allow variations of cross-section along the span, resulting in substantial

aerodynamic benefits. This approach is being employed in the

fabrication of the main rotor blades of the GKN Westland Helicopters

EH 101.

A composite (fiberglass and aluminum) is used in the tail assembly of

the Boeing 777 while the leading edge of the Airbus A310-300 and

A320 fin assembly is of conventional reinforced glass fiber construction,

reinforced at the nose to withstand bird strikes. A complete composite

airframe was produced for the Beechcraft Starship turboprop executive

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aircraft which, however. was not a commercial success due to its canard

configuration causing drag and weight penalties.

FUTURE USESThe environmental case for developing our understanding and

increasing our exploitation of composites is compelling .The Stern

Review, 2006,identified that 1.6% of globalgreenhouse gas emissions

come from aviation but that the demand for air travel will rise with our

income.To combat the environmental threat that aviation poses, the

Advisory Council for Aeronautical Research in Europe in 2002 laid out

targets to reduce the emission of CO2 (animport and greenhouse gas)

from an aircraft by 50% by 2020

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Conclusion

Due to their reduced weight and almost the same strength, composite

materials have an advantage over conventional metallic materials.

Although, currently it is expensive to fabricate composites, research is

being done to reduce initial implementation costs and address the issue

of non-biodegradability of current composites. If those few limitations

are overcome, then definitely composites are going to replace heavy

metals and become materials for the future.