Elasticity (physics)
 |
This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. Please help to improve this article by introducing more precise citations. (February 2012) |
| Continuum mechanics |
|---|
 |
In physics, elasticity is a physical property of materials which return to their original shape after the stress that caused their deformation them is no longer applied.
Contents |
[edit] Hooke's law
For small deformations, most elastic materials, such as springs, exhibit linear elasticity. This means that they are characterized by a linear relationship between stress and strain (the relative amount of deformation). This idea was first formulated by Robert Hooke in 1675 as a Latin anagram, "ceiiinossssttuu". He published the answer in 1678: "Ut tensio, sic vis" meaning "As the extension, so the force",[1][2] a linear relationship commonly referred to as Hooke's law. Although the general proportionality constant between stress and strain in three dimensions is a 4th order tensor, systems that exhibit symmetry, such as a one-dimensional rod, can often be reduced to applications of Hooke's law. However, most materials are elastic only under relatively small deformations, and so several conditions must be fulfilled so that Hooke's law is a good approximation. Because Hooke's law neglects higher order terms (so only the linear term dominates), in certain cases, such as rubbery materials, these conditions may not hold.
[edit] Transition to inelasticity
Above a certain stress known as the elastic limit or the yield strength of an elastic material, the relationship between stress and strain becomes non-linear. Beyond this limit, the solid may deform irreversibly, exhibiting plasticity. A stress-strain curve is one tool for visualizing this transition.
Furthermore, not only solids exhibit elasticity. Some non-Newtonian fluids, such as viscoelastic fluids, will also exhibit elasticity in certain conditions. In response to a small, rapidly applied and removed strain, these fluids may deform and then return to their original shape. Under larger strains, or strains applied for longer periods of time, these fluids may start to flow like a viscous liquid.
[edit] See also
[edit] References
- ^ Atanackovic, Teodor M.; Guran, Ardéshir (2000). "Hooke's law". Theory of elasticity for scientists and engineers. Boston, Mass.: Birkhäuser. p. 85. ISBN 9780817640729.
- ^ "Strength and Design". Centuries of Civil Engineering: A Rare Book Exhibition Celebrating the Heritage of Civil Engineering. Linda Hall Library of Science, Engineering & Technology. http://www.lindahall.org/events_exhib/exhibit/exhibits/civil/design.shtml.
