The document discusses major aircraft components and their functions, including the fuselage, wings, empennage, and engines, while emphasizing the significance of materials selection for aircraft design. It highlights the evolution of materials from high-strength aluminum alloys to advanced composite materials, which have become increasingly prevalent in both military and commercial aircraft for their weight-saving advantages. Additionally, it covers various materials used in aircraft manufacturing, such as titanium, aluminum, steel, and composites, and their specific properties and applications.

1. Major Aircraft
Materials and
Its
Classification
DR Karrar M. Hussein

2. Major Components of an Aircraft and Their Function
1.Fuselage
✓The fuselage is the main structural body of an aircraft which
carries the crew members, passengers, cargo, instruments,
and other essential equipment.
✓The fuselage has two major compartments. The upper
compartment is designated for the passengers, and the lower
compartment is structured for cargo storage and other
equipment for use by the aircraft

4. Major Components of
an Aircraft and Their
Function
2. Wing
• the wing is an airfoil-shaped
cantilever structure attached to
each side of the fuselage
• Wings provide the main lifting
surface from the bottom of the
wing and support the entire
weight of the aircraft in flight

5. Major Components of an Aircraft and Their
Function
3. Empennage
• The empennage includes the entire tail portion of the
airplane, consisting of vertical and horizontal
stabilizers
• The rudder is connected with the fixed vertical
stabilizer. The rudder is used to control yaw, the
horizontal movement of the aircraft.
• The elevators are connected to the two horizontal
stabilizers to control the vertical rotation, pitch of the
aircraft.

6. 4. Engine
• The aircraft is powered by the engines attached most to the leading edge of both the wings
• The engines provide the thrust to move the airplane forward after overcoming the total drag
of the aircraft.
• The engines also provide power to other units to generate electricity, hydraulic, and
pneumatic power to run instruments and move other devices including landing gear, flight
control wing surfaces, etc.
Major Components of an Aircraft and Their Function

7. Materials Selection
• Materials selection for the design of aerospace structure
depends on major critical requirements:
1.Environmental resistance (temperature and corrosion)
2.Stiffness
3.Static and dynamic loads
4.Durability (fatigue and damage tolerance including crack
growth and residual stress)

8. • Since the early 1920, the airframe structures have been built mainly with high
strength aluminum alloys (2xxx, 7xxx series). The overall compositions started
changing when high- performance polymer matrix composites were developed
during mid-1960s and early 1970s. Military aircrafts were the first applications of
composites materials. The earliest aircraft usages of composites were on the
empennages of the F-14 and F-15 military fighter jets in 1975. The usage of
composites, mainly carbon/epoxy, continuously increases in military applications
from 2% to 25% approximately by the early 1980s. The areas of application include
wing, forward fuselage and the horizontal stabilizer, with a typical weight savings of
approximately 20%. In the commercial aircraft industry, the application of composites
has accelerated in pace. Airbus started earlier (1972), using composite materials for
horizontal stabilizers and vertical fins for their A300 series aircrafts with great
success. However, Boeing has recently made significant changes in the commercial
aviation industry by using more than 50% composite materials in their new light
weight fuel efficient 787 series airplanes rolled out in 2007

9. Materials Selection
Major metals and materials used to manufacture aircrafts are as follows:
➢Aluminum
➢Magnesium
➢Titanium
➢High strength steels
➢Super alloys (nickel, iron-nickel, and cobalt based)
➢Composites (polymer, ceramic, and metal matrix)
Major structural metal components are made using various metal product forms
including sheet, plate, extrusion, and forging.

10. Major Aircraft Materials and Its Classification
• Major aircraft materials are classified according to their specific application in the aircraft.
These classifications could be structural, semi-structural, or non-structural, and for interior
applications. The primary aircraft structure can be broken into the following major
components as shown in:
1. Fuselage
2. Wing
3. Vertical stabilizer
4. Horizontal stabilizer
5. Engine
6. Landing gears
• In each major component of the airplane, the selection of materials is a critical part to ensure
the best design advantage of high strength-to-weight ratio.

12. • To satisfy the design requirements for any part of the major
components, the type of raw material, basic raw material
manufacturing process, and finally the producibility aspects of the
materials are considered to meet the customer requirements.
• Materials selection for the design of aerospace structure is the most
important factor to consider to satisfy the critical design factors
including structural stiffness, static and dynamic load-bearing capacity,
and durability (environmental resistance, fatigue, and damage
tolerance including crack growth and residual stress).

13. Major Aircraft Materials
•The major raw materials commonly used to build
aircraft structure are classified into two distinct
categories—metal structures and non-metal
structures. Primary metals are classified into two
groups including non-ferrous and ferrous alloys,
whereas non-metals like composite materials are
classified mainly into polymer, metal, and ceramic
matrices as explained in the tree diagram

14. Non-ferrous metals
• Aluminum alloys
• Titanium alloys
• Nickel alloys
Ferrous metals
• High strength alloy steel
• Stainless steel
Non-metals
• Composite materials

15. • A primary metal producer’s goal is to develop the material properties
to satisfy the following basic design requirements of aircraft
manufacturers:
1. Higher mechanical properties
2. Higher fracture toughness and damage tolerance
3. Improved corrosion resistance
4. Lower density
5. Product mix including sheet, plate, extrusion, forging, and tube

16. • Aerospace manufacturers will look to satisfy the following major
requirements before introducing the metal in the airplane structure:
✓Meet engineering design allowable values
✓Cost of raw materials
✓Meet producibility and quality requirements in terms of:
✓Formability
✓Cold and hot forming trials of extrusion, plate and sheet products
✓Effect of working strain on the final properties of metal structural
component
✓Machinability
✓Chemical finish
✓Corrosion and environmental effects

18. Aluminum
• Aluminum alloys have been the backbone of manufacturing aircraft just prior to 1920.
• Most of the advanced alloys are simply variants of 2024, which was introduced in
1921, and 7075 that was introduced in 1943.
• The 2024 alloy was first introduced in DC 3 aircraft in 1935. After a very long gap of
nineteen years, the first 7xxx series alloy 7075 was introduced in the Boeing 707
jetliner.
• Since then, the continuous development of both 2xxx and 7xxx series alloys by the
primary metal producers continued to meet the design needs of the aircraft.

23. • The aluminum alloys used for military aircraft are like those
on commercial aircraft, primarily 7075, 7175, and 2124
alloys.
• The 2124-T81851 thick plate materials are used to make
major bulkheads of F-16 and F-22 aircraft. In addition to
that, 7075-T76, 7475-T761 and 2024-T81, 2124-T81 are
used for sheet applications.
• The 2124-T81 plate product is also used for heavy structural
applications. The 6013 sheet also has potential for future
applications because of its improved formability as
mentioned earlier, excellent exfoliation corrosion resistance,
and lower cost.

24. • Aluminum–lithium (Al–Li) alloys were developed primarily for reducing
the weight of aircraft and aerospace structures. Al–Li alloys have
decreased density because of the very low density of metallic lithium.
• Addition of 1% lithium results in decreasing density of the alloy by 3%
and increases modulus by 6%. In addition to the main element lithium
(Li), copper (Cu), magnesium (Mg), zirconium (Zr), and silver (Ag) are
used as other alloying elements.
• Like other aluminum alloys, Al–Li alloys are heat treatable. Al–Li alloys
possess increased modulus of elasticity, high specific stiffness,
increased fatigue strength, and cryogenic strength.

25. • Alloys containing silver also have good weld ability. Addition of zirconium to
the alloy controls grain structure during heat treatment. The major
development work started in the 1970s, when aluminum producers
accelerated the development of Al–Li alloys as replacements for traditional
airframe 2xxx and 7xxx alloys.
• The development work led to the introduction of commercial alloys 8090,
2090, and 2091 in the mid-1980s.
• Several Al–Li alloys including 2055, 2060, 2098, 2195, 2198, and 2099 are
currently being used in modern aircraft. The cost of Al–Li alloys is typically
three to five times higher than that of the conventional aerospace alloys due
to relative high cost of lithium and high processing and handling cost. It is a
challenge to the aerospace industry to make proper trade study comparisons
with the Al–Li alloys to compete with the recent trend of using light carbon
fiber composite materials in the airframes.
• There is a positive trend to increase using Al–Li alloys in the fuselage and
wing structures of new commercial aircraft.

26. Titanium
• The use of titanium in aerospace applications is growing due to its high strength,
excellent corrosion resistance, and elevated temperature properties and also having
lower density by 40% than that of steel and nickel-based alloys.
• Owing to initial high cost of raw materials followed by costly forming and machining
operations, the use of titanium is generally limited. But some primary benefits must be
considered to justify on a part-by-part basis against the added cost. The primary benefits
for the gradually increasing use of titanium in the aerospace industry include:
1)Weight savings
2)Space limitations: Replacement of aluminum alloys. Volumetric constraints provide the
opportunity for some of the largest titanium components such as landing gear beams.
3)Operating temperature: Replacement of aluminum, nickel, and steel alloys.
4)Corrosion resistance: Replacement of aluminum and low-alloy steel.
5)Composite compatibility: Replacement of aluminum alloys.

27. • Titanium alloys used in aircraft cover the entire range of commercially produced
conventional alloys including commercially pure (CP) Ti, Ti-3Al-2.5V, and Ti-6Al-4V, Ti-
6Al-2Sn-4Zr-2Mo, Ti-10V-2Fe-3Al, Ti-15V-3Cr-3Al-3Sn, and more. CP titanium with
formability and corrosion resistance has driven its use from α or super-α type alloys such
as Ti-6Al-2Sn-4Zr-2Mo for high temperature applications to α/β alloys such as Ti-6Al-4V,
which is widely used in the aerospace industry, and β alloys such as Ti-10V-2Fe-3Al. Ti-
6Al-4V was developed in the late 1950s and still represents approximately 80% of the
aerospace market.
• It is a moderate strength alloy with minimum ultimate strength (UTS) of about 130 ksi and
can be utilized for every product shape including sheet metal, extrusion, forging, and in
tube form. Since the application of titanium is growing faster, the aerospace industries
are exploring more to manufacture wide variety of parts used for aerospace vehicles
including fixed wing aircrafts, rotary aircrafts, and also jet engines.

28. Steel
•The structural steel alloys used in the commercial
aircraft are mainly the high strength low-alloy steels
such as 4340, 4330, and 4340 M.
•These alloys are used when very high strength (275–
300 ksi) requirements are needed to satisfy the
working stress of the parts such as landing gear and
flap tracks.

29. • But the protective finishes are required to address general corrosion
and stress corrosion issues.
• More recent commercial models and their derivatives have started
using high strength corrosion-resistant steels such as 15-5PH
wherever possible.
• Relative to high strength low-alloy steel, 15-5PH steel reduces
manufacturing flow time and costs in production.
• The only limitation of 15-5PH steel is the range of the maximum UTS
(180–200 ksi).

30. Composite Materials
• Gross weight of an aircraft is a big concern to make it fuel-efficient. Weight-to-power ratio
needs to be optimized to make the aircraft more efficient. The demand for low-density
composites and other non-metals have continued to go up to make the aircraft lighter.
• Carbon fiber composites have been used in applications for some structural and mostly
semi-structural parts for quite some time. Continuous improvements in the technology of
fabricating large structural carbon fiber composite parts have given a new direction to the
aircraft manufacturers to explore many different designs to make the aircraft more fuel-
efficient as delivered to the airline or military customers. Molding technology helps to
make an integral or one-piece part to avoid many joining processes with many metal
fasteners.

31. The most revolutionary
commercial aircraft to date,
the Boeing 787, introduced
in 2011, is made with 50%
composite materials

32. There is also a continuous growth of use of
composite materials in military applications

33. • The trend of increased use of composite materials in the
airframe structure is also being pursued by the other prime
aerospace manufacturing companies including Airbus for
their new A350.