Draw S-N curve for steels and show endurance limit on it.

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 S - N curve

In S-N curve, 'S' stand for "Stress" arising out of repetitive load and 'N' stands for "Number of cycles to failure".

The fatigue strength more appropriately termed the endurance limit is usually determined from a polished specimen subjected to reversed bending.




The graph mentioned above is an example of S-N curve. The line is downward-sloping. Where the endurance limit is shown. Endurance limit is the stress level below which a specimen can withstand cycle stress indefinitely without exhibiting fatigue failure. But failure will occur often a diminishing number of cycle as the range increases above this limiting value. The endurance limit for more of steels is found to be roughly half of the ultimate tensile stress.






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