Poisson's Ratio

The Poisson's ratio, also known as the transverse contraction coefficient, is a dimensionless material constant that describes the ratio of the relative transverse strain to the relative longitudinal strain of a material under uniaxial tensile or compressive loading. When a material is stretched or compressed in one direction, a corresponding transverse contraction or transverse strain occurs perpendicular to the direction of loading. The Poisson's ratio is defined by the formula ν = -εₜ/εₗ, where εₜ is the transverse strain and εₗ is the longitudinal strain.

For most metallic materials, the Poisson's ratio is typically between 0.27 and 0.30. For stainless steel, especially austenitic alloys such as material 1.4301 (X5CrNi18-10), the Poisson's ratio is approximately 0.30. This ratio is important for calculating deformations and stresses in components, as it provides information about the three-dimensional deformation behaviour of the material. A precise understanding of the Poisson's ratio is therefore essential for the accurate design and analysis of stainless steel structures.