FATIGUE%20

1
FATIGUE FAILURESVARIOUS MECHANICAL COMPONENTS
Cracks in bicycle frame
Helical gear
Spring
Steering arm
Pedal
Stub axle
Bolt
Shaft - torsion
Source The Open University - http//materials.ope
n.ac.uk/mem/mem_mf.htm
2
AEROSPACE INDUSTRY
December 19, 2005, off Miami Beach, Florida,
Grumman G73T Turbo Mallard seaplane Fatigue
cracks in the right wing.
Lading gear fatigue failure
Aloha Airlines Flight 243 - April 28,
1988 Cracks in the fuselage
3
SHIPS
USS Tanker ship fractured in January 1943

• Liberty ship - USS Carlos Carillo
• 2,751 built between 1941-1945
• Built from welded sections
• 1500 instances of significant brittle fractures
• 19 ships broke in half without warning
• Steel embrittlement
• Cracks initiated from stress concentrators
• Crack propagation along weld lines
• (source www.wikipedia.com)

4
STRESS ANALYSIS FINITE ELEMENT METHOD
Airplane wing spar
5
NOTCHED SPECIMENS DUCTILE FRACTURE STUDIES
Finite element analyses
Scanning electron microscopy