Question

What is elastic fatigue?

Answer 1

- Hint: The name itself suggests that it involves elastic exertion due to repetitive moments. It is a property of an elastic body due to which it becomes less elastic as it has been subjected to repetitive deforming forces alternatively.

Complete step-by-step solution -

Elastic fatigue happens when a body is subjected to repeated strains or deforming forces, even within elastic limits. Under such circumstances a body loses its property of elasticity.
Let us take two wires A and B of the same material. We will subject the wire A to repetitive deforming force for several days and leave the wire B untouched. Now, after several days if we give similar vibrations to both the wires it is observed that the vibrations in the wire A would die sooner and the wire B would vibrate for a longer time. The wire B is observed to have more elasticity and the wire A has undergone elastic fatigue.
Example- It is suggested that after a certain time the bridges must be demolished and reconstructed as they might have developed elastic fatigue.

Additional Information:
Elastic fatigue can be considered similar to the physical fatigue in human beings. If a person is tired for a few days, taking one day off might relieve his stress and relieve him from fatigue and he would regain his productivity, similarly if a body is not subjected to deforming forces, it can be relieved of the elastic fatigue.

Note: Students must remember that if a body is subjected to a deforming force beyond its elastic limit it will get permanently deformed. Elastic limit is the maximum extent up to which a deforming force can be applied without permanent alteration of the shape of a body.