German did lot of damage to British
Liberty ships
Fracture Surface¶
- Ductile fracture
- Cup and cone
- Slow
- Brittle fracture
- Fast
Experiment: Fatigue Failure of a Paper Clip
The material responds to cyclic loading very differently from static loading. The failure mechanism is also different.
Fatigue Failure¶
Mechanical Fatigue¶
Fatigue failure of Jack Hammer
- Initiation point
- Beach marks (fatigue crack striations)
- overload
Thermal Fatigue¶
Fretting Fatigue¶
- contact stress \(\implies\) fretting fatigue
- max stress at subsurface