Strain

Strain

The ratio of change in the configuration of shape,length or volume to the original configuration of the body is called strain.

**Strain has no unit**

There are 3 types of strains:

• Longitudinal Strain

This type of strain is produced when the body is under the tensile tress or compressive stress.

It is defined as the  ratio of the change to the original length of the body.

∴Longitudinal Strain = Change in length  =  ΔL

                                       Original Length        L

• Volume Strain

This type of strain is produced when the body is under the bulk stress. It is defined as The ratio of change in volume to the original volume of the body.

∴Volume Strain = Change in Volume  = -  ΔV

                                Original Volume         V

**-ve sign shows that the volume decreses when the body is under bulk stress**

• Shear Strain

This type of strain is produced when the body in under the tangential stress. It is defined as The angle (𝛳 ) through which the face of a body, originally perpendicular to the fixed face is turned when it is under shearing stress.

Tan𝚹 = 𝔁   or  𝚹=  𝔁

               L                  L

**when 𝚹 is small, then tan𝚹 ≃ 𝚹**