In a typical stress-strain curve, Which of the following is the elastic limit point?

CONCEPT:

• Stress-Strain Curve determines how a material behaves how it has a relationship between the strain and stress for a given material.
  • We apply a force on a material cylinder and record the change in length at various applied forces to cause the strain.

The curve for steel looks as follows:

• With the assistance of this curve, we can understand how the material behaves with increasing loads.
• Analysis of the Curve

1. The region between O and A, the curve is a straight line in this region. Hence, Hooke’s Law obeys in this region.
2. Region from A to B, the stress is not proportional to strain in this region. However, if we remove the load the body will return to its original dimension.
3. Point B for a typical stress-strain curve is the elastic limit or Yield Point and the stress at this point is the Yield Strength (Sy) of the material. This is the point upto which, when the load is removed, the body still returns to its original dimension.

EXPLANATION:

• Elastic limit point is the point up to which a material behaves as an elastic body i.e. when the load is removed the material comes to its original shape and size.

• From point O to point A, a material follows Hook's law.
• But up to point B the material follows elastic property.
• So up to point B, if the load is removed from the body it will come to its original shape.
• So point B is the elastic limit point.

• Hence the correct answer is option 2.