Theory 25/Offshore & Marine Engineering
Mooring Fatigue Is a Period Ratio
The claim
Mooring line fatigue is set by the ratio of wave period to the line's natural period rather than by wave height, so a moderate sea near resonance can do more damage than a storm off it.
01Mechanism
Dynamic amplification peaks when forcing matches the line's natural period; tension ranges, and therefore fatigue, follow the amplification.
02Predictions
- P1Damage should peak at a period ratio of one.
- P2Wave height alone should mispredict.
03Refutation
Damage tracking wave height would remove the resonant term.