What is the term for the ratio of lateral strain to longitudinal strain in materials?

The term that describes the ratio of lateral strain to longitudinal strain in materials is Poisson's Ratio. This ratio is an important material property that indicates how a material deforms in directions perpendicular to the applied force. Specifically, when a material is stretched or compressed along one axis, it tends to expand or contract in the perpendicular direction; Poisson's Ratio quantifies this behavior.

For example, in a tensile test where a rod is pulled, it elongates in the direction of the applied force (longitudinal strain), while simultaneously exhibiting a reduction in diameter (lateral strain). The value of Poisson's Ratio helps engineers predict how a material will behave under various loading conditions, which is critical for structural analysis and design.

Other choices like Young's Modulus and Modulus of Elasticity relate to the material's stiffness, describing the relationship between stress and strain in the linear elastic region. Elasticity Coefficient is not a standard term used in material science, making it less relevant to the question. Understanding Poisson's Ratio is essential in fields such as civil engineering, materials science, and mechanical engineering, as it influences design decisions to ensure safety and performance of structures.