Elastic fatigue:

When the piece of material is stretched and then allowed to return to its original shape multiple times, the molecules in the material begin to deform and the bonds between them gets weaken. After a while, the material can even break. This is fatigue of elastic. When a wire is made to vibrate for the long time, it is found that the wire gets tired because of continuous vibrations which are known as elastic fatigue. It is loss of strength of the material because of repeated alternating stress to which the material is subjected is called as elastic fatigue.