what is poisson effect
The Poisson Effect When a tensile stress is applied to a material, the material elongates in the direction of the applied stress, and contracts perpendicular to the direction of the applied stress. This relationship, called the Poisson effect, is a natural response to applied stress that occurs with all materials, but is particularly apparent with ductile materials. For example, when a metal bar is pulled in a tensile test, it stretches out and necks down on. the sides.