Relative Axial Strain

Published: November 7, 2019 | Last updated: July 5, 2023

What Does Relative Axial Strain Mean?

Relative axial strain in a material refers to the strain in the direction of the applied load. It is an important component of Poisson's ratio which is the ratio of the relative lateral strain to the relative axial strain. Poisson's ratio varies with the material. The axial strain is positive in tension and negative in compression.

Trenchlesspedia Explains Relative Axial Strain

When an axial bar is subjected to a tensile force, it elongates by a certain length. Assuming the bar is of length L and cross-sectional area A, and the change in length is ΔL, the strain (ε) is given by:

ε = ΔL / L (change in length divided by original length)

The strain in the direction of the load is called axial strain, and is associated with an increase in length. The axial strain is positive in tension i.e. if ΔL is greater than zero, ε is less than zero. Since strain is very small or fractional, it has a non-dimensional length and is given as a percentage by multiplying by 100%.