# Elongation Percentage

on . Posted in Classical Mechanics

Elongation percentage, abbreviated as E_p, a dimensionless number, also called percentage elongation or percent elongation, is a measure of the extent to which a material stretches or deforms under tensile forces.  It quantifies the increase in length of a material specimen when subjected to tensile testing.  In tensile testing, a standardized specimen is subjected to an applied tensile load until it fractures.  During this process, the specimen undergoes deformation, and its length increases.  The elongation percentage provides a measure of how much the material elongates or stretches before failure.

The elongation percentage is an important mechanical property used to assess the ductility or malleability of a material.  Ductile materials, such as metals and some polymers, exhibit significant elongation before fracture, indicating their ability to deform plastically without breaking.  Brittle materials, on the other hand, typically exhibit low elongation percentages, as they tend to fracture without significant plastic deformation.

### Elongation Percentage Formula

$$E_p = ( l_f - l_i ) \; 100 \;/\; l_i$$     (Elongation Percentage)

$$l_f = l_i + ( l_i \; E_p \;/\; 100$$

$$l_i = 100 \; l_f \;/\; E_p \; 100$$

Symbol English Metric
$$E_p$$ = elongation percentage $$dimensionless$$
$$l_f$$ = length of fracture $$ft$$ $$m$$
$$l_i$$ = initial length $$ft$$ $$m$$

Tags: Strain and Stress