Strain & Types of Strain

Strain:

When a body is subjected to some external force, there is some change of dimension of the body. The ratio of change in dimension of the body to the original dimension is known as strain.

Or, The strain (ϵ) is the deformation produced by stress. Strain is dimensionless.

Types of Strain:

 

There are mainly four type of strain

• Tensile Strain

• Compressive Strain

• Volumetric Strain

• Shear Strain

Tensile Strain:

When a tensile load acts on a body then there will be a decrease in cross-sectional area and an increase in length of the body. The ratio of the increase in length to the original length is known as tensile strain.

ϵ_t= δL/L

The above strain which is caused in the direction of application of load is called longitudinal strain.

 
Another term lateral strain is strain in the direction perpendicular to the application of load i.e., δD/D.

Compressive Strain:
 

When a compressive load acts on a body then there will be an increase in cross-sectional area and decrease in length of the body. The ratio of the decrease in length to the original length is known as compressive strain.

ϵ_c= δL/L

Shear Strain:

When a body is subjected to two equal and opposite forces, acting tangentially across the resisting section, as a result of which the body teds to shear off the section, then the stress induced is called shear stress. The corresponding strain is known as shear strain and it is measured by the angular deformation accompanying the shear stress.

Volumetric Strain:

It is defined as the ratio between change in volume and original volume of the body and is denoted by ϵ_v.