Elastic deformation is a physics term referring to the process an object undergoes where it retains it shape after deformation once pressure is removed. Sometimes also referred to as reversible deformation, linear elastic deformation (linear relationship between stress and strain) is governed by Hooke’s law of elasticity, which states that a spring’s extension is directly proportional to the applied load.

A sample of elastic deformation is a hard spring.  When normal pressure is applied to a hard spring it contracts, thereby changing its shape. However when that pressure is removed, the spring goes back to its original shape. The same happens when normal pulling is applied to the spring: once released it goes back to its original shape. To illustrate the opposite, take a block of brick. When adequate pressure is applied and the brick breaks, this is called plastic deformation because the object did not go back to its original shape once the pressure was removed.

Elastic deformation data is used in stress tests and tensile tests, which determines the maximum stress (stretching or compressing) a material can be put under until it achieves plastic deformation, or irreversible deformation, which is the opposite of elastic deformation. Some practical applications include determining the maximum load of an elevator, or the maximum load for a bridge.