Question

Draw a typical Stress-Strain curve for a metal. Mention yield point and fracture point.

Answer 1

Point B is yeild point

Point F fracture point

The graph shows variation in stress and strain of a metal wire.

Some points about the graph are-

1. The line between the point O to B is straight which shows that the metal wire is elastic in nature and can retain its original shape.
2. After putting stress on the metal wire the stress increase upto point E .
3. The stress gradually increase upto point F which is not able to retain its original shape.
4. After point F if the stress is increased the strain starts  to decrease and the wire get break there so it is known as breaking or fracture point .

Answer 2

B Yield point

E Fracture Point

Detailed Answer :

• The stress is proportional to strain upto point, where, Hooke's law is fully obeyed. Point A is known as proportional unit.
• When stress is increased beyond A, then for a small stress there in large strain in the wire upto B. When the load is reduced between points O and B, then the wire comes back to its original position.
• The wire regains its original position only when load applied is less than or equal to certain limit. This limit is called elastic limit. The point B on the curve is known as elastic limit or yield point.
• But, if the stress is increased beyond B, the strain further increases and the wire does not come back to its original position after removing load. It is deformed permanently.
• As the stress in further increased beyond C, there is a large strain in the body and the wire breaks at point E called fracture point.