Ch 2 - Wing Structural Details Flashcards
Wing structural details
What are the 4 main structural wing components
Spars, ribs, skin and stiffeners
What proportion of a wing is taken up by: main structural box, flaps ailerons & othe rlift control devices, and the slats/services etc?
~40%, ~40%, ~20%
What is a stringer?
Spanwise component that runs the length of the wing and transfers aerodynamic loads from the skin to the structure. Positioned between the ribs and the skin.
Name 5 considerations that dictate wing structure design.
Strength Durability Stiffness Aerodynamic forces Subsystems
What aerodynamic requirements are there on the wing structure?
To maintain shape under aerodynamic loading
What strength requirements are there on wing structure?
Span & chord wise inertial & aerodynamic loads without failure
What durability requirements are there on wing structure?
Must be able to endure all operational load cycles with no risk of catastrophic fatigue damage
What subsystems requirements are there on wing structure?
Fuel storage, under carriage, flaps and control surfaces, fuselage coupling and supporting engines
What stiffness requirements are there on wing structure?
Resist undue deformation (elastic instabilities)
What is the main function of a spar?
To carry vertical shear forces and direct bending stresses. They form part of the wing torsion box.
What is the main function of ribs?
Hold the skin in the correct shape
Transfer aero forces to spars
Carry shear force, bending moments and in plane tension & compression
Provide support for stringers
What is the main function of skin?
Provide smooth aerodynamic shape
Resist pressure / suction without distortion
Resist internal fuel pressure and inertial loads
Carry direct compressive & tensile stresses
Carry shear stresses during wing twist
Resist fatigue failure from cyclic loading
Give two examples of the cross section of widely used built up stringers.
Z section J section (upside down capital J)
Give two examples of integral stringer cross section shapes.
Integral Z section
Integral blade section (single upright piece)
That is the main function of stiffeners?
Attach spanwise members to the skin
Resist compressive buckling
Ribs supporting stringers increases the buckling load
Explain what a doubler is.
A piece of material that overlays an access port or similar, bonding to the skin surrounding the port and to the port itself.
Explain what a crank stopper strap / reinforcing flange is.
Strip of material bonded to another component which acts to hold the main component together if a crank attempts to propagate through it. Wing stringers can act and crack stoppers. sometimes fail-safe straps are bonded to the skin between ribs.
The 787 Dreamliner is comprised of how much composite material by weight?
50%
List 5 advantages of composite materials in aviation. What do these advantages lead to?
- Allow for lighter structures
- Allow for simpler structures
- Easier to visually inspect
- Does not corrode or fatigue
- Damage can be repaired in less than 1 hour
- Resist impacts better
- Reduced scheduled maintenance
- Resists crank propagation
These advantages mean:
- Increased efficiency
- Reduced fuel consumption
What do thermoplastic CFRPs offer over theermoset CFRPs?
They can be re-melted for easy recyclability whilst maintaining their composition.
Do composites have higher or lower stiffness to weight ratio?
Higher - intrinsically
How can composites be tailored to improve aeroelasticity?
Unidirectional laminates can be used in wing construction to stop wing twist, instead the will will bend upward.
Disadvantages of composite structures?
Delamination from out f plane loads, compressive loads. This is normally internal so hard to visually inspect.
A detailed understanding of the load path of the structures is required which isnt required for metals.
Imbalance of deformation between composites and metals leads to joint failure.
Drilling holes breaks fibres,
