|The graph mentioned above is an example of S-N curve.
The lins is downward-sloping. We can see from this graph that the more
the number of cycles becomes,
The smaller stress even causes fatigue fracture.
However, we can find one line that it won't fracture by getting a load
as long as the load is one constant repeatitive stress.
It is called Fatigue Limit.
These are some new theories as follows these days and the research of them
has been proceeded.
"Is the fatigue limit which appeared until 107 times real one? "
"Fatigue fracture might actually happen if the test is continued to
Giga-cycle regime,that is , further than conventuional regime.
Several cases have been found to fracture.