Stress is P/A and Strain is δ/L.

Here, c is considered is constant.

For the mild steel, and for the semi ductile there are some important factors important as –

• The suspended load is axial and thus it must generate a uniform stress.
• The homogeneous material is required.
• Cross-section of the specimen must be constant.

In the above diagram, you can see a number of fundamental concepts related to the curve and it is very important to understand each factor –

• Proportional Limit (A) –

A is the exact point in the diagram where stress ∝ strain.

• Elastic Limit (B) –

In the diagram of stress – strain, B is the elastic limit that indicates that elastic material regains its exact position like before without fixing up any permanent set.

• Yield Point as C or C’ –

Without increasing of stress there is an appreciable deformation. In this diagram, you can see two different points as C and C’ and they are known as yield points.

• Ultimate Stress (D) –

Stress –Strain diagram this is the highest Ordinate.

• Rupture Stress (E) –

At the point where the material or the object breaks is known rupture stress.  Calculation of the stress is very important for a proper and nominal diagram. Moreover, it is also important for you to understand that E will be lower than the value of ultimate stress (D).

• Actual Rupture Stress (F) –

It can easily be calculated on the basis of the actual area and this can be taken as the narrow down or the necking phenomena.