The ratio of change in configuration to the original configuration is called strain. It has no dimensions and units.
Strain are of three types :
(1) Linear strain : Linear strain
Linear strain in the direction of deforming force is called longitudinal strain and in a direction perpendicular to force is called lateral strain.
(2) Volumetric strain : Volumetric strain
(3) Shearing strain : It is defined as angle in radians through which a plane perpendicular to the fixed surface of the cubical body gets turned under the effect of tangential force.
φ = x/L
When a beam is bent both compression strain as well as an extension strain is produced.
