Poisson’s Ratio

Poissons ratio

It has been found experimentally that when a body is stressed within elastic limit, the lateral strain bears a constant ratio to the linear strain, Mathematically,

Lateral strain/Linear strain= Constant

This constant is known as Poisson’s ratio and is denoted by 1/m or μ.
Following are the values of Poisson’s ratio for some of the materials commonly used in engineering practice.

Values of Poisson’s ratio for commonly used materials.
Table 1 Values of Poisson’s ratio for commonly used materials.

Poisson’s Ratio (υ) = – lateral strain / Axial strain

= – εx/εz

= -εy/εz

= – [∆d / do] / [∆l/ lo]

εx =εy = – υ εz               The negative sign is added to yield a positive value for υ

Poissons ratio
Fig. 1 Poissons ratio


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