Definition(s)
S-N Curve
Quantitative relationship between the fatigue stress, S, and the number of cycles, N, corresponding to a specific probability of failure for a detail, derived from test data.
Source: API Technical Report 17TR7, Verification and Validation of Subsea Connectors, First Edition, April 2017. Global Standards
S-N Curve
A plot of stress range (S) against the number of cycles (N) to failure obtained by cycling specimens to failure.
Source: API Standard 2RD, Dynamic Risers for Floating Production Systems, Second Edition, September 2013. Global Standards
S-N Curve
Graphical presentation of the dependence of fatigue life, N, on fatigue strength, S. NOTE It is also known as the Wöhler curve.
Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards