Strain
• Definition: It is the change in length per unit length.
• It represents the relative deformation of an object that is subjected to stress.
• It may be elastic, plastic or both elastic and plastic.
• It is denoted by “ε”.
• Designated as ΔL / L. So, it is unitless.
• Strain(ε)= Deformation/Original length
.When the force is applied, the rod's length changes from its original length L0, to the extended length L1. The resulted strain, É›, is given by
É› = (L1- L0)/ L0
strain
In an object subjected to stress
Stress-Strain Relationship
• If a bar of material is subjected to an applied force, F, the magnitude of the stress and the resulting deformation (É›) can be measured.
• This is done with tensile, compressive or shear loading of samples using universal testing machine.
• Graph representing stress (or load) and strain (elongation) can be obtained.
