Elasticity

Elasticity is the ability of a material, which under stress, recovers its original shape after the removal of the external load. If the material regains its original shape then it is said to be perfectly elastic. Steel, copper, aluminium, etc., may be grouped under perfectly elastic materials within certain limits of deformation. Thus, for each material, there is a critical value of load, generally known as the elastic limit, which makes for the partial breakdown of elasticity. Loading the material beyond this point leads to permanent deformation.