Lecture 7 Flashcards
1
Q
Why is ductile failure preferable to brittle failure?
A
Ductile = lots of warning Brittle = sudden & catastrophic
2
Q
How does toughness relate to brittleness/ductility?
A
Low toughness = brittle
High toughness = ductile
3
Q
What is toughness?
A
A material’s ability to resist a crack
4
Q
What do brittle/ductile fractures look like?
A
Brittle: flat
Ductile: cup-and-cone
5
Q
What must be known about applied loads?
A
- Magnitude
- Static or cyclic
- Orientation (especially for anisotropic materials)
6
Q
What methods can be used to calculate loads?
A
- Analytical
- Numerical
- Experimental
7
Q
What is the critical load?
A
The smallest load which can cause failure
8
Q
What is included in ‘geometry’?
A
- Shape of the component
- Stress concentrations
- Size, shape and position of any defects
9
Q
What causes breakages at lower loads than expected after a long usage period?
A
Fatigue
10
Q
What are welds sensitive to?
A
Fatigue- they are fine under static loading
11
Q
Why are welds difficult to predict?
A
- Large number of different defects
- Not uniform in geometry
12
Q
What does critical load calculation depend on?
A
- Failure mechanism
- Fracture mechanics parameters
- Manufacturing defects
