Aircraft make use of all sorts of materials in manufacture. Although principally a metal aircraft, composite materials play an increasing role in construction due to their impact on overall weight.
2024 aluminium alloy is the basic aluminium alloy used for such parts as fuselage frames and stringers, empennage and flight control skins.
7075 aluminium alloy is primarily used for fuselage skins, cabin floor frames and things like flap spars.
7475 aluminium alloy is a high corrosion resistant alloy with good toughness qualities. It is used for fatigue and fracture critical components such as the wing rear spar.
7050 aluminium alloy is a high strength, stress corrosion resistant alloy. It has higher fracture toughness qualities than other high strength alloys. It is used on some aircraft for the upper wing skin.
TITANIUM has excellent high strength and low weight characteristics. It is used primarily for engine mounts, windshield bolts and cabin floor screws. Its high cost prevents its widespread use.
KEVLAR is DuPont Company's registered trademark for its aramid fibers which are excellent fibers for the reinforcement of plastics. Kevlar is yellow-brown in colour and in its dry (non-impregnated) state is very similar to fiberglass cloth.
This composite material is used in non and semi-structural components such as fairings, radome, tailcone, cowlings, ducting, etc
Kevlar has several excellent characteristics:
Lightweight (about one half the weight of aluminium).
High strength.
Stiffness (modulus) (but not as stiff as graphite).
Specific tensile strength (highest of any commercial reinforcing fibers or metals)
High stress tension fatigue resistance.
Vibration damping.
Due to its high-strength and low weight properties, many aircraft components are made from this material.
GRAPHITE EPOXY, also called Carbon Fibre Reinforced Plastic (CFRP), is a composite material that uses carbon fibre matting to reinforce plastic. It is several times stiffer than regular glass fibre material and is jet black in colour. Some characteristics of graphite epoxy are:
High strength
Low co-efficient of thermal expansion
Good friction and wear properties
Excellent fatigue life
Conductivity to heat and electricity
Graphite epoxy is very light; about half the weight of aluminium alloy. Some aircraft use graphite epoxy for fuel tank access panels, wheel discs etc. empennage top, centre and aft dorsal fairings.
It is also used as a hybrid with Kevlar with NOMEX honey-comb for the cabin floor panels
General repairs to these materials are covered in the Structural
Repair Manual for the specific aircraft.
Hope this helps
Regards
The Doc
Ref. Various course notes, and books etc.