What is similitude of fatigue Explain the fatigue growth beh

What is similitude of fatigue? Explain the fatigue growth behavior in metals.

Solution

Answer 1:

Structural Testing is used to verify the static strength or fatigue strength of a component by applying measured loads to the test item. The cost and time involved in testing of big structure like an aircraft is very high.

The “Similitude Concept” is used in the fatigue analysis of various structures. According to this concept engineers can relate the behaviour of small test specimens result obtained under carefully controlled conditions, to the likely performance of real structures subjected to variable amplitude fatigue loads under either simulated or actual service conditions.

The Similitude Concept states that if the instantaneous loads applied to the ‘test’ structure (Skin with hole) and the test specimen (Small plate with hole) are the same, then the response in each case will also be the same and can be described by the material’s S-N curve. Due account can also be made for stress concentrations, variable amplitude loading etc.

This will significantly reduce the cost and time involved in the resting of structures.