When a body is subjected to some external force, we observe some change in dimension of the body. The ratio of change in dimension to the original dimension of the body is known as "Strain". Strain is Dimensionless quantity.
Strain is classified into:
1. Tensile strain
2. Compressive strain
3. Volumetric strain
4. Shear strain
If there is some increase in length of a body due to some external force, then the ratio of increase in length to the original length of the body is known as Tensile strain. But if there is some decrease in length of the body, then the ratio of decrease in length to the original length of the body is called as Compressive strain.
The ratio of change in volume to the original volume of the body is called Volumetric strain.
The strain produced by the shear stress is known as Shear strain.
Credits: Mechanical engineers