1. DEPARTMENT OF AEROSPACE ENGINEERING
A REVIEW OF COMPOSITES ON AIRCRAFT STRUCTURES
GROUP MEMBERS:
1. HIDAYATULLAH BIN MOHAMMAD ALI (183243)
2. FAJOBI ABEEB OLAMILEKAN (181268)
3. NURFAIZAH BINTI MOHAMAD (184655)
4. MAISARAH AFIQAH BINTI NASARUDDIN (184049)
5. MUHAMMAD AFIQ BIN AHMAD WIZRAN (178744)
EAS3401
AEROSPACE MATERIALS AND PROCESSESS
18TH NOVEMBER 2015

2. INTRODUCTION
Composites material have been used on aircraft structures since last decades until now. The
permanent interest of this specialists increases where there are more application of composites on
modern aircraft rather than olden days. A composite material is one which composed of at least two
elements working together to produce material properties that are different to the properties of those
elements on their own. The first time composite used on the aircraft was after the Second World War
on the military sites. The use of composites on aircraft structure do reduce the weight in structural
design. For advantages, composites offer high strength and stiffness to weight ratio comparing to
metal alloys. It also corrosion resistance and act as excellent fatigue properties. In the other hand, for
disadvantages, composites are low fracture toughness and moisture absorption.
The main reason why the composites takes too long to be applied on the aircraft structures
from the last decades is because of the cost. The cost of aircraft components or structures that made
out of composites is quite high rather than similar structures that was made out of alloys, mainly
aluminium, metal and et cetera. They are relatively low through-thickness strength, low resistance to
mechanical damage and temperature limitations (compared with titanium alloys). That is where the
manufacturer prefer to produce aircraft structure using other structures made of alloy, metal or others
rather than composites mainly because of these reasons.
Now, with continuous developments in materials, design, and manufacturing technology, composites
are having more advantages over other materials such as metals.
SOURCE: Chris red, Composites Forecasts and Consulting
SOURCE: Chris Red, Composites Forecasts and Consult

3. LITERATURE REVIEW
Currently a large variety of composite components are used in aircrafts. Composites play a vital
role to assure the integrity of the aircraft such as the primary structure components, the control
components, exterior and also the interior components. Thus, composite materials have a lot of
application when involves with aerospace components. Composite are made up by combining several
materials in order to improve the characteristics and the properties of the materials from its individual
original material. A composites materials are mostly preferred than its original material for reasons
such as it is stronger, lighter, or less expensive. The use of composite materials is abundant in
aerospace field because of the properties it exhibit. It is applied in manufacturing various parts of the
aircraft structure.
The appeal of higher strength, stiffness and lower density, combined with great resistance to
fatigue and corrosion led to the use of metal. But weight has also always been a consideration. These
factors and its durability have propelled carbon fiber/epoxy to widespread use in aerospace and a
variety of high performance applications. Carbon fiber construction offers exceptional strength and
stiffness at a lower density that metal materials.
Other types of composite materials are glass fibre reinforced plastic GFRP which are used in
fairing, storage room doors, floors and passenger compartments. There are a large range of desirable
mechanical, chemical, electrical and other properties can be obtained in this present development. A
lot of analysis of glass-resin composite properties points to several areas where improvements and/or
manufacturing techniques would lead to improved properties.
Composites are versatile which can be used for both structural applications and components, in
all aircrafts and spacecrafts. Applications of composite materials are very broad. The types have
different mechanical properties and are used in different areas of aircraft construction. For example,
carbon fiber and glass fibre has its own properties. Carbon fiber are known for its unique fatigue
behavior whereas glass fibre are known for its high strength-to-weight ratio and also its good
dimensional stability.

4. APPLICATION OF COMPOSITES ON AIRCRAFT STRUCTURES
Written by HIDAYATULLAH BIN MOHAMMAD ALI (183243)
Primary Structures in Commercial, Aerospace, Marine, Industrial, and Recreational
Structures are primarily made up of commercial material. Based on the book ‘Engineering Materials
Properties and Selection’ by Budinski K. G. page 32, Composites was created from a combination of
materials mixed together to achieve specific structural properties, the independent materials in
composites do not dissolve or merge completely but rather act together as one. By joining the various
properties, a superior material is produced. The high strength, low weight and corrosion-resistant
materials of composites are quickly becoming more important to aircraft structure. Composites are
essentially plastics reinforced with carbon fibers. Carbon fibers, each no longer than a human hair,
are set into resin to form sheets, or plies. Plies are laid on top of each other to form sub-components.
The strength and stiffness of the materials depends on the direction at which the plies have been laid
together. There are many application of composites on the aircraft structures including fairings, flight-
control surfaces, landing-gear door, leading- and trailing- edge panels on the wing and stabilizer,
interior components, floor beams and floor boards, turbine engine fan blades and primary wing and
fuselage structure on new-generation aircraft. Advanced composites do not corrode like metals. A
combination of corrosion and fatigue cracking is a significant problem for aluminium commercial
fuselage structure. For information, Boeing 787 aircraft used approximately 50% of its airframe from
composites. A very bold move in the commercial aircraft industry.
As for Airbus, during
the past 30 years,
AIRBUS has
continuously and
progressively
introduced composite
technology as a
consequence of
successful experience
accumulated (Figure
1).
The application of composites does not only limited to the exterior of the aircraft but it was also long
used on the interior components and fixtures of the aircraft such as floor boards, lavatories, galleys,
bulkheads and cabin dividers, wall and ceiling panels and stowage bins. Composite materials will
Figure 1 : Evolution composite application at airbus

5. play an increasingly significant role in aerospace application. Boeing 737 and now the Airbus 350-
XWB (Figure 2) has used
more than 50% composite
materials comparing to
previous types of aircraft.
With their unique
combination of properties
such as high strength, low
weight, low flammability,
non-toxicity and durability,
smoke density and heat
release, composites are ideal
and one of the best material
for many aerospace
applications, both interior and
exterior components.
References:
1 Budinski K. G. (2009)
The Nature of Composites
Engineering Materials Properties and Selection, Nineth Edition, Page 32.
2 Baker, A. A. (Alan A.) (2004)
Introduction and Overview
Composites Materials for Aircraft Structures, Second Edition, Page 1.
3 Soutis C. (2005)
Progress in Aerospace Sciences 41
Fibre reinforced composites in aircraft construction, Volume 1, Page 148-150.
4 Trilaksono A. (2014)
Automatic Damage Detection and Monitoring of a Stitch Laminate System Using a Fiber Bragg
Grating Strain Sensor
Open Journal of Composite Materials, Volume 4, Page 1.
5 FAA, Sky horse Publishing, Inc (2014)
Composite Materials in Aircraft
Pilot’s Handbook of Aeronautical Knowledge, Volume 1, Page 2-9
Figure 2 : Airbus 350 XWB Structural Design

6. PROPERTIES OF A COMPOSITE MATERIAL ON AIRCRAFT STRUCTURES
Written by FAJOBI ABEEB OLAMILEKAN (181268)
Chemical & Weathering Resistance:
Composite products have good weathering properties and resist the attack of a wide range of
chemicals. This depends almost entirely on the resin used in manufacture, but by careful selection
resistance to all but the most extreme conditions can be achieved. Because of this, composites are
used in the manufacturing. A surprising number of applications where composites are used involve
occasional or prolonged contact with chemicals. These chemicals can be anything from cleaning
agents, acids, alkalis, fuels, hydraulic and brake fluids, de-icers, paint strippers, lubricants, etching
chemicals, flue gases and event food and drink.
The resistance of composites to highly reactive chemicals is generally very good, which in turn
explains their widespread use in the chemical process equipment industry where it is often difficult
to find any other affordable, process able materials capable of withstanding the very harsh conditions.
It is rare for composite components to be attacked as rapidly as some common metals are when placed
in contact with acids.
DURABILITY:
The durability of any material is determined by its resistance to the damaging effects of an influence
such as extreme temperature, ultra-violet radiation, exposure to aggressive chemicals, stress cycles,
etc. Durability is assessed by measuring an appropriate material property such as strength, modulus,
etc., before and after exposure to one or more such influence for a period of time under prescribed
conditions. A high level of property retention is consistent with high (good) durability. In this respect,
the "lifetime" of a material may be identified with the time of exposure that results in a particular
property remaining above a certain level. All composite materials are durable in as much as they are
water resistant, thermally stable and cannot rust.
In almost all applications, the durability of a composite material may be enhanced by imposing a
conservative safety factor (2-4) on the design, and in many such cases additional durability may be
achieved by the use of a protective coating and/or the incorporation of light stabilisers and
antioxidants.
JOINING:
Joints are a potential source of weakness for any structure, and can also add additional weight
therefore the ideal structure should be designed with as few joints as possible. This is not always

7. achievable in practice, however, as there is generally an upper limit to the component’s size due to
process ability and/or to facilitate the transportation and assembling on-site.
However, these will only become materials-of-preference if better ways can be found for producing
more efficient joints. Methods of mechanical fastening and adhesive or thermal bonding (welding)
have been developed but are often extensions of methods used for joining conventional metallic or
polymeric structures. To enable effective joint design, this must be integrated at the material and
structure synthesis stage.
There are many formalised fibre-reinforced polymer (FRP) composite repair procedures prepared by
reputable organisations throughout the world, all evolved from good historical industry practice and
adapted to the specific conditions of each sector. All successful repairs carried out to any substrate
rely on skilled repair technicians, good surface preparation, well designed repair procedures and the
use of first rate materials. They currently also depend on stringent quality-control encompassing
reliable damage detection, surface cleanliness and texturing examination, drying to known limits,
undertaking work within permitted temperature and humidity envelopes, and controlling resin cure
to manufacturers recommendations.
References:
1 H.KAWADA ET AL. 2005
LONG-TIME DURABILITY OF POLYMER MATRIX COMPOSITE UNDER HOSTILE
ENVIRONMENT: MATERIAL SCIENCE AND ENGINEERING VOLUME 412, PAGE
159 – 164
2 BRUCE K. DONALDSON, 2008
THE MECHANICAL BEHAVIOR OF ENGINEERING MATERIALS
ANALYSIS OF AIRCRAFT STRUCTURE PAGE 109
3 GORGR MURRAY ET AL. 2007
COMPOSITE
INTRODUCTION TO ENGINEERING MATERIAL PAGE 265

8. ADVANTAGES AND DISADVANTAGES OF THE APPLICATION OF COMPOSITES
MATERIALS ON AIRCRAFT STRUCTURES
Written by NURFAIZAH BINTI MOHAMAD (184655)
Composites materials such as nickel-based superalloys which is one of the high-performance
alloy is used in making the fundamental components of the aircraft turboshaft engines. According to
the article ‘Nickel-Based Superalloys for Advanced Turbine Engines: Chemistry, Microstructure and
Properties’ in Journal of Propulsion and Power, by Pollock, T.M., and Tin, S., nickel-based
superalloys is a composite material which has a low-density characteristic are fatigue and corrosion
resistance and could withstand temperature up to 1200 ºC. Refractory composites are use in
manufacturing the segment that are in contact with hot gases in the engine. This composites materials
are designed to be used at high temperature ranging from 1000ºC to 1200ºC, whereas the separation
of fiber from the matrix prevents crack propagation. Composites are also use in repairing components
of the aircraft as it contains fiber dominated properties that are fatigue resistance. For example, the
use of boron/epoxy composites can be used to detect crack underneath repairs by using eddy current
methods. Another advantages of using composites in repairs is that it can be formed into desired shape
into the repair during cure process. The NASA space shuttle uses a number of composite parts such
as graphite/epoxy cargo bay door because it offers significant advantages over conventional metallic
materials as it has a high stiffness to weight ratio, low thermal expansion coefficients, and good
vibration-damping properties.
The drawback and limitation such as the high cost of fabrication might be a disadvantage of using
composites materials. For example, a part that is made up of graphite/epoxy composites may cost up
to 10 to 15 times of the cost of the materials itself. The repairs of composites also are not a simple
process compared to intermetallic materials, thus the critical flaws and crack sometimes might go
undetected. When composites materials are used for bonded repairs, it has approximately short shelf
life (in uncured state) and has low coefficient of thermal expansion. Thermoplastic composites that
are used in the manufacture of the interior parts of an aircraft, has a high viscosity where it requires
high temperature and pressure for processing with a high tendency for voids to occur.

9. References
1. Pollock, T.M., & Tin, S. (2006)
Nickel-Based Superalloys for Advanced Turbine Engines: Chemistry, Microstructure and
Properties.
Journal of Propulsion and Power, 22(2), 361-374.
2. Gay, D., & Hua, S.V. (2002)
Composite Materials: Design and Applications, 2, 181-185.
3. Gibson, R.F. (2011)
Principles of Composites Materials Mechanics, 3, 18-21.
4. Kaw, A.R. (2005)
Mechanics of Composite Materials, 2, 8-12.
5. Jones, R. Baker, A.A, Rose, L.R.F, et al. (2002)
Advances in The Bonded Composites Repair of Metallic Aircraft Structure, 1, 19-30.
6. Hua, S.V (2009)
Principles of The Manufacturing of Composites Materials, 90-91.

10. MECHANICAL BEHAVIOUR OF GLASS FIBRES WITH THE REINFORCEMENT OF
ALUMINIUM OXIDE AND SILICON CARBIDE
Written by MAISARAH AFIQAH BINTI NASARUDDIN (184049)
Of all the composite materials incorporating glass as a continuous or disperse phase, glass fibre-
resin composites are said to be by far the most important one. Composite systems , glass fibre-resin ,
have become industrially important in all areas where a high strength-to-weight ratio is required and
in applications where complex shapes of limited number are called for. For the aerospace
components, some of the application of glass fibre reinforced plastic GFRP composites are like radar,
flaps and etc. The Resin transfer moulding is a method of plastic casting in which the mould is filled
with a liquid synthetic resin , which will then be allowed to hardened at room temperature. The
materials used are glass fibre, resins either polyesters or epoxides and silicon carbide (SiC) and
aluminium oxide.
S. Rajesh et al.(2014) did an analysis on the mechanical behaviour of glass fibre/ Aluminium
oxide and Silicon Carbide reinforced polymer composites, Manufacturing and Management ,P598-
606 and it was founded that by adding a high strength of Aluminium oxide fibre will constraint the
deformation in the matrix which leads to the reduction of fatigue ductility. Whereas, VijayaRamnath
et al.(2014) concluded that the polyester resin composite produce higher shear strength which will
improved the stiffness and the strength of the materials. However for Park et al. ,he explained that
the fracture toughness of the MMC will be decreased due to the increase in volume fractions of
Aluminium Oxide varying from 5-30% .
An experiment had been conducted to characterise aluminium oxide and silicon carbide
reinforced polymer matrix by enhancing it with samples of resin such as epoxy and polyester. From
the experiment, Sujan et al. had studied the performance of the reinforced composite materials. It has
shown that the exhibition of composite materials improved the physical and mechanical properties ,
such as low coefficient
of thermal expansion,
high ultimate strength
up to 23.68% high
impact strength and
hardness.
Table 2 , adopted from
(S. Rajesh et

11. al.(2014),601) shows various samples of different composition to compare the mechanical properties
of the four samples
A few mechanical testing were done on the composites such as the biaxial stresses, tensile
test, impact test and also
hardness test in order to
know the mechanical
properties of the
fabricated composites.
Figure 5 adopted from
(S. Rajesh et al.(2014),
604) shows the result for
the tensile test. It can be
seen clearly that the
samples that are made
with epoxy resin have higher strength compared with the one made with polyester resin. After
obtaining the data from other mechanical testing, it shows that composites with epoxide resin have
greater strength as compared to the composites with polyester resin.
Reference
1. Gay D. & Suong V. (2007). Composite Materials: Design and applications (2nd ed.).CRC Press
2. S. Rajesh et al.(2014) ,mechanical behavior of glass fibre/ Aluminium oxide and Silicon Carbide
reinforced polymer composites, Manufacturing and Management ,598-606
3. Patel P.,Bhavin S.,Saurin S., Tejas P.(2015), Experimental Analysis and Prediction of Kerfwidth
in Laser Cutting of Glass Fibre Reinforced Plastic Composite Material, Manufacturing and
Application, 139-146
4. V.S. & Bhagwat J.(2015), Study on Jute and Glass Fibre Reinforced Polypropylene and Epoxy
Composites,Vol1, 5-10
5. A.P. Chakraverty, U.K. Mohanty,S.C. Mishra & B.B. Biswal (2014), Evaluation of GFRP
Composites under the exposure to Up and Down-Thermal Shocks,Advanced Science Letters,
Vol.20, 671-675

12. FIBERS FOR POLYMER-MATRIX COMPOSITES FOR CARBON FIBERS
Written by MUHAMMAD AFIQ BIN AHMAD WIRZAN (178744)
1. Overview
As a result of their strong sense interatomic bonds, elements low atomic number, such as C, B, A1
and Si, may in rigid, low-density materials are formed. These materials are to be performed for the
elements themselves or of their compounds or with oxygen or nitrogen. [1]
The strong bonding [2] inhibit plastic flow, at least at temperatures below approximately half the
melting temperature. Since these materials are not to facilitate capable of stress concentrations due to
plastic flow, they will be markedly weakened by sub microscopic open fault, in particular those to
the surface. Thus, it is only when they usually made in the form of fibers, which can be realized the
inherent high strength of these materials. [3, 4]
2. Manufacture.
Carbon fiber is widely used for airframe, engines and other aerospace application. Table 1 below
shown the High Modulus ( HM , type I) , high strength ( HS , type II ) and intermediate modulus (
IM , Type III ).
Table 1 - Typical Properties for the Major Types of Commercial Carbon Fibers [1]
“Graphite is a form of carbon that is strong covalently bound plane parallel to the hexagonal base in
three dimensional lattices. Weak ties atom scattering Van der Waals ' enables easy slip basal plane,
the basis for the lubricating properties of graphite.” [1]
Carbon fibers are made of organic precursor material through the process carbonization. The bulk of
the carbon fibers used in aerospace and other structures application, made of polyacrylonitrile (PAN)
fibers. [5] Carbon fiber is also performed with various forms of field. [6]

13. 3. PAN-Based fibers.
Polyacrylonitrile (PAN), also known as Creslan 61, is a synthetic, semi- crystalline organic polymer
resin, a linear formula (C3H3N) n. Although it is a thermoplastic, it is not liquid under normal
conditions. [7] PAN is acrylic textile fibers produced by wet or dry spinning from basic polymer or
copolymer which is produces round smooth fibers whereas wet spinning produced many of cross-
sections. There are several advantages in the non-circular cross-section for example, the larger the
surface area relative, the stronger the effective bond. The fibers are stretched during the process of
spinning. The greater the strain occurs, the smaller diameter fiber and more options molecular
orientation along the fiber axis. [1]
4. Pitch-Based Fibers.
Pitch is the precursor materials are relatively inexpensive to manufacture carbon fiber. [6] however,
despite the low cost fiber can be produced from isotropic pitch; they have mechanical properties
rather poor. The main advantages of this process route processing PAN, is that there is no the tension
required to develop or maintain a desired molecular orientation achieve a high modulus and strength.
A very high value of Young's modulus and heat and electricity conductivity can be obtained from the
fiber pitch as shown Table 2. [1] Therefore, it is widely used in space- based applications where ultra–
high stiffness and conductivity is very advantageous.
Table 2 – Detail of the mechanical properties of Carbon Fibers (The temperature Column is the
Nominal Maximum Operating Temperature in an Inert Environment) [1]
5. Why use composite material in aircraft structures?
Carbon Fiber is used in a large number of industries, in a variety of ways, due to its many advantages
including long lasting durability and strength. Carbon Fiber is used for Aerospace, Aircraft,

14. Automotive, Sport Equipment, and Medical Equipment to name a few. Its versatility, strength, and
durability make it valuable in many industrial applications. Some of its major benefits include 70%
Lighter than steel, 40% lighter than aluminium, high strength to weight ratio, high corrosion
resistance, application flexibility and low mass and provide a smooth surface, improve fuel efficiency,
less maintenance and repair costs.
Reference
1. Composite Materials for Aircraft Structures Second Edition “Fibers for polymer-matrix
Composites” written by Alan Baker, Stuart Dutton and Donald Kelly (year 2004)
2. Kelly, A., Strong Solids, 3rd ed., Clarendon Press, Oxford, UK, 1986.
3. Watt, W., and Perlov, B. V., (eds.), Handbook of Composites: Volume 1 Fibers, 1985, edited by
A. Kelly, and Y. N. Rabotnov, Series Ed. North Holland,
4. Chawla, K. K., "Fibers," Composite Materials: Science and Engineering, Spinger- Verlag, 1987,
Chap. 2.
5. Shindo, A., "Polyacrylonitrile (PAN)-Based Carbon Fibers," Comprehensive Composite Materials,
edited by A. Kelly and C. Zweben, Vol. 1, Elsevier, 2000.
6. Diefendorfe, R. J., "Pitch Precursor Carbon Fibers," Comprehensive Composite Materials, edited
by A. Kelly and C. Zweben, Vol. 1, Elsevier, Cambridge 2000.
7. A. K. GUPTA, D. K. PALIWAL, P. BAJAJ. Journal of Applied Polymer Science, Vol. 70, 2703–
2709 (1998)

15. SUMMARY / CONCLUSION
This report provided a review on composites for aircraft structures. The main reason,
composite materials are selected for the components because of weight savings for its relative
stiffness and strength. For example, carbon fiber reinforced composite material can be up to five times
stronger than 1020 stainless steel while it is only one-fifth of the weight. Aluminium (6061 grade),
the composite modulus and up to seven times are much closer to weight carbon fiber composite,
although still a little heavier, but twice as strong.
The biggest advantage of modern composites is that they are strong and light. By choosing a
suitable combination of matrix and reinforcing material, a new material be made that the requirements
of a particular application met exactly. Composites also offer design flexibility, since many of them
can be moulded into complex shapes. The disadvantage is often the cost. Although the resulting
product is more efficient, the raw materials are often expensive. However, they provide opportunities
for the production of lighter cars and planes (the less fuel than the heavier vehicles, we will use now).
The new Airbus A380, the world's largest passenger aircraft, makes use of advanced composites in
its design. Over 20% of the A380 is increasingly made of composite materials, mainly plastic with
carbon fibers. The design is the first large-scale use of glass-fiber reinforced aluminium, a new
composite material that is 25% stronger than conventional aircraft aluminium but 20% lighter.
All composite materials, the glass as a continuous or disperse phase are fiberglass -
Composites be by far the most important because of high strength-to-weight ratio. Resin transfer
moulding or plastic casting will be allowed hardened at room temperature which needed by using
glass fibre, resins either polyesters or epoxides and silicon carbide and aluminium oxide. A few
mechanical testing were done on the composites and as result the samples that are made with epoxy
resin have higher strength compared with the one made with polyester resin. It means that composite
with epoxy resin have higher strength compared from composite with polyester.
For a polymer matrix composite (PMC) consists of a thermosetting or thermoplastic resin with
fibers, which increases very much stronger and stiffer than the matrix. PMC are attractive because
they lighter, stronger and stiffer than conventional unreinforced polymers or metals, with the added
advantage that their properties and can be met to the needs of a particular application. High-fiber
reinforcements are of the greatest interest for military and aerospace composite applications such as
carbon fibers. Were developed as a high-performance carbon fibers, their high cost limits their use
on high value military aerospace systems. The result of the early military composite development
programs can be seen in system fielded by each of the military services today. For example, more
than 350 parts of the F-22 Raptor, a share of 25 percent of the structural weight, are carbon-epoxy

16. composites. Furthermore, the development Joint Strike Fighter 25-30 percent will be composite
weight. The army now uses carbon thermoplastic composites in large-scale production of clogs for
the M829A3 ammunition. Carbon fibers is expected that an even greater role in the aerospace industry
application system of the future to play.