Poisson's Ratio

ν = - ε_{lat} / ε_{long}

Lateral strain over axial strain (opposite sign, hence the minus). Elastic isotropic: ν between 0 and 0.5. Steel ≈ 0.27–0.30; rubber near 0.5 (incompressible); cork near 0. Concrete ≈ 0.2. Shear modulus G = E / [2(1+ν)].

$ν$: Poisson's ratio
$ε_{long}$: Axial strain
$ε_{lat}$: Lateral strain

Step-by-step solved example

Bar stretched ε_long = 0.001, ν = 0.30. Lateral strain?

Axial stretch and lateral contraction: ν = −ε_lat/ε_long.

1. Definition
ε_lat = −ν ε_long = −0.00030 (contraction).
$ε_{l a t} = - 3.0 \times 1 0^{- 4}$

Answer: −3.0×10⁻⁴ (contraction)

10 practice questions

0/10 correct

1.ν for steel is nearest

2.ν = 0.5 means the material is

3.G in terms of E and ν is

4.If ν = 0, stretching causes

5.Axial tension produces lateral

6.Volume strain εv ≈

7.Concrete ν is typically about

8.E = 200 GPa, ν = 0.3. G ≈

9.ν is dimensionless because it is

10.Plane strain (εz = 0) develops σz =