Richard,
The equation we used for fatigue curve for
cuni is
Log10 (N) = c + ( m * Log 10(s))
where N= no of cycles
c = constant = 13.5014
m = constant = -5.0268
S = allowable stress in MPa
K.R.Srinivasan
Pipe stress consultant
Singapore.
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K. R. SRINIVASAN