Definition of Strain:

Within the use of metal for mechanical engineering reason, a provided state of stress commnly exists in a considerable volume of the material. A Reaction of the atomic structure will manifest itself on a macroscopic scale. Thus, while a stress (no matter how small) is applied to a metal, the proportional dimensional change or distortion have to take place.

Such a proportional dimensional change (intensity or degree of the distortion) is known as strain and is measured as the total elongation per unit length of material due to a few applied stresses. Equation described this proportion or distortion.

Strain =ε =δ/L

where:

ε = strain (in. /in.)

δ = total elongation (in.)

L = original length (in.)