Beryllium Copper. The ratio is named after the French mathematician and physicist Siméon Poisson. It is denoted by the symbol μ. For rubber its value varies from 0.45 to 0.50. It means that when a material is loaded within elastic limit than the ratio of lateral strain to the longitudinal strain gives us a constant called poisson’s ratio. Poisson's Ratio Equation & Definition. Mathematically Aluminum, 2024-T4. 0.35. For small values of these changes, $${\displaystyle \nu }$$ is the amount of transversal elongation divided by the amount of axial compression. 0.32. 0.285. Most materials have Poisson's ratio values ranging between 0.0 and 0.5. Value of Poisson ratio for stable, isotropic materials should lie in between -1.0 to 0.5. With Poisson's ratio for aluminum 0.334 - the contraction can be calculated as. The value of poisson’s ratio varies from 0.25 to 0.33. Aluminum, 6061-T6. 0.32. Aluminum alloy. In materials science and solid mechanics, Poisson's ratio $${\displaystyle \nu }$$ (nu) is a measure of the Poisson effect, the deformation (expansion or contraction) of a material in directions perpendicular to the direction of loading. The value of Poisson's ratio is the negative of the ratio of transverse strain to axial strain. Incompressible materials, such as rubber, have a ratio near 0.5.