Aircraft Structures and Materials Flashcards

What is the purpose of anodizing aluminum aircraft parts?

Answer: To create a hard corrosion-resistant oxide layer on the surface

Anodizing electrochemically thickens the natural aluminum oxide layer, providing enhanced corrosion protection and a base for primers.

Which structural concept describes a design where the skin carries all structural loads with no internal framework?

Answer: Monocoque

A true monocoque structure relies entirely on the outer skin to carry all structural loads without an internal supporting framework.

When a metal is described as 'work hardened,' what has happened to it?

Answer: Its hardness increased due to plastic deformation from cold working

Work hardening (strain hardening) occurs when plastic deformation from cold working causes dislocation buildup, increasing hardness and strength.

What is the primary structural function of wing ribs?

Answer: To maintain the airfoil shape and transmit loads to the spars

Wing ribs maintain the airfoil cross-sectional shape and transmit aerodynamic loads from the skin to the spars.

What is the key characteristic of a thermosetting resin used in composite aircraft structures?

Answer: It permanently cross-links during cure and cannot be re-melted

Thermosetting resins (such as epoxy) form permanent cross-linked polymer chains during curing and cannot be re-melted or reshaped.

Fatigue cracks in aircraft metal structures most commonly initiate at what locations?

Answer: Stress concentrations such as holes, notches, and fastener holes

Fatigue cracks almost always initiate at stress concentrations—holes, notches, grooves, or fastener locations—where local stress is highest.

What is the 'safe-life' structural design philosophy?

Answer: A structure is retired at a defined service life before fatigue failure is expected

Safe-life design retires structural components after a calculated service life before the probability of fatigue failure becomes significant.