In solid mechanics, elasticity is the property of materials which undergo reversible deformations under applied loads.

The deformation of a solid is part of the study of solid mechanics. In solid mechanics, a material behaves elastically if it changes shape due to an applied load, and that when the load is removed, recovers its original shape. In solid mechanics theory, every material changes shape when loads are applied to it, though very small loads produce very small deformations. Furthermore, most solid materials will undergo elastic deformation as long as the loads are kept under a certain limit. This limit is known as the elastic limit or the yield strength of the material, and is one way of defining its strength.

Elastic deformation can be either linear or nonlinear. In linear elasticity, the elastic deformation is directly proportional to the applied load. The elasticity of a solid is inversely proportional to its stiffness. Stiffness, when corrected for the dimensions of the solid, becomes modulus of elasticity, which is an intensive property of the material. The stiffness of a structure is of principle importance in many engineering applications, so modulus of elasticity is often one of the primary properties considered when selecting a material. A high modulus of elasticity is sought when deflections are undesirable, while a low modulus of elasticity is required when flexibilty is needed.

See also

• Elasticity (physics)