Knee KN

This point is found by bisecting the angle between the initial tangent and another tangent drawn to the curve beyond the knee region. The worth of this technique can be judged from the following considerations  

In view of these considerations, it is considered fruitless to attempt to define a precise point for any value between LL and KN. Fatigue, cyclic load, and environmental allowables will have to be determined in other ways. 

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