Poisson's ratio is
- the ratio of the relative contraction strain (or transverse strain) normal to the applied load - to the relative extension strain (or axial strain) in the direction of the applied load
Poisson's Ratio can be expressed as
μ = - εt / εl (1)
where
μ = Poisson's ratio
εt = transverse strain
εl = longitudinal or axial strain
Strain can be expressed as
ε = dl / L (2)
where
dl = change in length (m, ft)
L = initial length (m, ft)
For most common materials the Poisson's ratio is in the range 0 - 0.5.