What Is Poisson ’s Ratio ? Poisson ’s ratio is “the ratio of transverse contraction strain to longitudinal extension strain in the direction of the stretching force.” Poisson ' s ratio is a measure of the deformation of a material in directions perpendicular to the loading. Learn about its origin, values, applications, and examples of materials with positive, negative, or auxetic Poisson ' s ratio . Poisson ' s ratio is the ratio of lateral strain to axial strain in a material under uniaxial loading. It ranges from -1 to 0.5 and depends on material composition, temperature, strain rate, loading conditions, and anisotropy. Poisson's ratio is the ratio of expansion along one axis to contraction along the opposite axis when a material is subjected to tensile or compressive forces. Applying tensile strain to a rubber band, for example, causes it to elongate axially and contract in the transverse direction, becoming thinner as it simultaneously becomes longer.
