Question

define poisson's ratio

Answer 1

the ratio of the proportional decrease in a lateral measurement to the proportional increase in length in a sample of material that is elastically stretched.

Answer 2

Poisson's ratio is a material constant that relates stress in one direction to elastic strain in another.
*Stress describes an external force applied to a material
*Strain measures the change in shape as a result of that force.

μ = - εt / εl

where

μ = Poisson's ratio

εt = transverse strain (m/m, ft/ft)

εl = longitudinal or axial strain (m/m, ft/ft)