1Materials For AIRCRAFTS

Presented by

Jabin Mathew Benjamin

13MY04

Dept. of Metallurgical Engineering

2Indian aviation industry

• Passenger traffic: 160 million in 2013

• Freight traffic: 2.2 million tonnes in 2013

• Aircrafts: fastest mode of transport

• Major role in defence

• Safety main concern• Environment and mechanical conditions

3MATERIALS FOR AIRCRAFTS

• Function• Carry passenger and cargo load via air route

• Constraints• Factor of safety (1.2 - 3)• Corrosion resistant

• Objectives• Maximize strength • Minimize mass

• Free variables• Material• Cost

4Material indices

Strength to weight ratio or specific strength

Maximize ( / s r)

5Screening

Source: Figure 4.4, Micheal F. Ashby, Materials selection in mechanical design, 3 rd edition, 2005 [1]

61903 - First Flight - The Wright Brothers

• Wood - natural composite - high strength to weight ratio

• Easy to work • Tough and flexible

• Moisture absorption• Anisotropic

[2]

71915 – First all-metal Junkers J-1

• Steel

• Weight – sluggish• Unmaneuverable in flight

• Wtal = 1/3 wts

[2]

8 1917 - Junkers J-7

• Duralumin – Al, 4% Cu, Mg and Mn

• Al – 2024, 7075

• Subsonic aircraft

• US Navy – Alclad• duralumin with pure aluminum coating

• Al-Li alloys • Airbus A350 - wings and fuselage

• Supersonic - elevated temperatures 

• Aluminium – low heat resistance

Source: Figure 4.4, Micheal F. Ashby, Materials selection in mechanical design, 3 rd edition, 2005 [1]

9Titanium

• High strength

• 40% lighter than steel

• Good creep properties

SR-71 Blackbird - highest flying, fastest aircraft(wings and fuselage – titanium)

10Composite

Fibreglass - Boeing 707 - 1950s – 2% of the structure• Weight reduction• High corrosion resistance• Good fatigue strength• Reducing operating costs - fuel• Improved efficiency

• GLAss-REinforced” Fiber Metal Laminate (FML)• Good impact and fatigue strength• Better corrosion resistance• Better fire resistance• Lower specific weight

112009 – Boeing 787 Dreamliner

Weight breakdown by material type:

 

50% composite (fuselage, wings, tail, doors and interior)

20% aluminum (wing and tail leading edges)

15% titanium (engines components)

10% steel (various locations)

5% other

• 80% composite by volume

• 20% more efficient than the 767

12The Tejas – India’s indigenous LCA

• CFC upto 45%• Fuselage (doors and skins)• Wings (skin, spars and ribs)• Tailfin, rudder, air brakes and landing gear

doors.• Fewer joints or rivets

• 40% reduction - number of parts

• Weight lowered by 21%

• Shorter time to assemble• 7 months as opposed to 11 months using an

all-metal airframe.

Source: http://www.tejas.gov.in/technology/composite_materials.html

13Reference

1. Micheal F. Ashby, Materials Selection In Mechanical Design, 3rd Edition, 2005

2. Peter L. Jakab, Wood To Metal: The Structural Origins of The Modern Airplane, Journal of Aircraft, Vol. 36, No. 6, November – December 1999\

3. Júlio C. O. Lopes, Material Selection For Aeronautical Structural Application, Ciência & Tecnologia Dos Materiais, Vol. 20, 2008

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