Fatigue Introduction

Question 1

Fatigue

Answer 1

Progressive deterioration of the strength of a material or structural component during service

Question 2

Types of Fatigue (5)

Answer 2

Thermal, Acoustic, High Cycle, Fretting, Corrosion

Question 3

High Cycle (HCF)

Answer 3

Aerodynamic excitation
Mechanical vibration
Airfoil flutter
Acoustic fatigue

Question 4

Cyclic Fatigue Load Actions (x7)

Answer 4

Pressure cabin load cycle
Ground-air-ground cycle
Manoeuvres and gust encounters
Landing jolt & taxiing
Fluctuations in thrust forces
Moving flaps induce stress cycle
Engines

Question 5

Safe-life

Answer 5

How long before catastrophic failure
End of safe-life must be replaced

Question 6

Fail-safe

Answer 6

Designed to withstand structural damage without compromising safety up to critical damage size which can be visually detected in inspections

Question 7

Safe-life components

Answer 7

Landing gear
Major wing joints
Hinge pin of an all-moving tail
Hinge pin of a variable-geometry tail

Question 8

Fail-safe components

Answer 8

Stiffened wing skins
Stiffened fuselage skins
Items amenable to inspection