The fractional change in configuration is called strain.
Strain = Change in the configuration / Original configuration,It has no unit and it is a dimensionless quantity.
According to the change in configuration, the strain is of three types
(1) Longitudinal strain= Change in length / Original length
(2) Volumetric strain = Change in volume / Original volume
(3) Shearing strain = Angular displacement of the plane perpendicular to the fixed surface.
