Slide 1 Flashcards
Aluminium
- Most used Material for the fuselage,wing and supporting structures
- Properties are controlled by their alloy composition and heat treatment
Reasons for aluminium usage :
- Low cost
- Easy fabrication
- Light
- Good Stiffness, strength and fracture toughness
Problems with using aluminium alloys:
- Damage by Corrosion
- Low Fatigue Resistance
Titanium
- in Airfram Strc. and jet engine components
- Fan blades low pressure comp. parts and plug and nozzle assemblies in exhaust
- Used in most heavily loaded strc. that must occupy minimum space like landing gear, wing- fuselage connections
- Weight of titanium in commercial airliners under 10% ,in fighter aircraft app. 25-35%
Reasons
- High Stiffness,strength toughness fatigue resistance
- Excellent corrosion resistance
- High Temperature Resistance
Problems
- Expensive
- Heavier than Al
Magnesium
ONE OF THE LİGHTEST METALS
Problems
- high cost
- lower stiffnes and strength compared Al alloys
- Low Corrosion resistance
- 2% in modern aircraft and helicopter
- use in non-gas turbine engine parts and apps include gearboxes and gearbox housings of piston engine aircraft and the main transmission housing of helicopters
Steel
alloyed and Heat treated for very high strength
5-10% in total
Good Choice for Safety critical Strc. Comp.
Reasons
- High Strength
- High Elastic Modulus
- Good Fatigue Resistance
- High Fracture Toughness
Problems
- High Density
- High corrosion for some alloy types
Super Alloys
- A Group of Ni, iron- nickel and cobalt alloys used in jet engines
- Most important >nickel-based material with high con Cr Fe Ti Co and other alloying el.
- Ni superalloys can operate for long periods of time at 800-1000 C
- Using in High Press. Turbine blades, discs, combustion chamber, afterburners and thrust reversers
Reasons
- Dimensional Stability at high temperatues Stiffness toughness strength
- Good Corrosion and oxidation resistance at high T
Fibre-Polymer Composites
- Made of Continuous fibres in a polymer matrix
- Carbon fibre composites are used in major strc. of aircraft like wings fuselage empennage and control surfaces
- Glass Fibres are used in randomes and semistructural components like fairings
- Aramid fibres used in the cooler part of jet engines lik inlet fan blades to reduce Weight
Reasons
- Light
- High stiffnes strength and fatigue resistance
Problems
- high cost
- low impact damage resistance
Fibre-Metal Laminates
- consisting of thin bonded sheets of metal and fibre- polymer composie
- Most common FML is Glare Al alloys + fibregass comp
Reasons
- Lighter, higher in strength nd more fatigue resistant than monolithic metals
- Better impact strength and damage tolerance than compsites
Strength
is the resistance offered by a material when subjected tı external loading
Elasticity
is power of coming back to its original position after deformation when the load is removed
Plasticity
is ability to undergo some degree of permanent deforemation without failure
Ductility
Enables a metal to draw out into thin wire on app of load
Malleability
is ability to be flattened into thin sheets without cracking by hot or cold working
Conductivity
is ability to conduct heat and electricity
Toughness
is ability to withstand both plstic and elastic def.
hardness
is ability of material to resist scratching abraison indentation or penetration
