Fracture
Separation of a solid into more than 1 parts under load or stress.
Based on the type of load:
- Tensile fracture
- Compressive fracture
- Shear fracture
- Fatigue fracture
- Creep fracture
Characterized into 2:
- Ductile fracture
- Brittle fracture
Ductile fracture
Materials show significant amount of plastic deformation prior to fracture. Fracture surface gives cup & cone appearance. Aka. cup-and-cone fracture.
Steps:
- Specimen forms a neck
- Cavities start to form within the neck
- Cavities join with each other and form a crack
- Crack propagates towards surface perpendicular to stress
- Direction of crack changes to
Brittle fracture
Little or no plastic deformation prior to fracture. Fracture surface is smooth.
More dangerous than ductile fracture.
- No warning sign
- Crack propagates at very high speeds
- No need for extra stress during crack propagation.