Poisson’s ratio of Soda Lime Glass and Borosilicate Glass

Poisson's ratio of a material defines the ratio of transverse strain (x direction) to the axial strain (y direction)

Inmaterials scienceandsolid mechanics,Poisson's ratio is a measure of the Poisson effect, thedeformation(expansion or contraction) of a material in directions perpendicular to the specific direction ofloading. The value of Poisson's ratio is the negative of the ratio oftransverse strainto axialstrain. For small values of these changes, is the amount of transversalelongationdivided by the amount of axialcompression. Most materials have Poisson's ratio values ranging between 0.0 and 0.5. For soft materials, such as rubber, where the bulk modulus is much higher than the shear modulus, Poisson's ratio is near 0.5. For open-cell polymer foams, Poisson's ratio is near zero, since the cells tend to collapse in compression. Many typical solids have Poisson's ratios in the range of 0.2-0.3. 

The ratio is named after the French mathematician and physicist Siméon Poisson.