Fatigue life prediction of mooring chains for a floating tidal current power station

Abstract

As a kind of clean and renewable energy, tidal current energy is becoming increasingly popular all over the world with the shortage of energy and environmental problems becoming more and more severe. A floating tidal current power station is a typical type of tidal current power transformers which can sustain the loads of wind, waves, and current, and even the extreme situation of a typhoon. Therefore, the mooring system must be reliable enough to keep the station operating normally and to survive in extreme situations. The power station examined in this paper was installed at a depth of 40 m. A 44 mm-diameter R4-RQ4 chain was chosen, with a 2 147 kN minimum break strength and 50 kN pretension. Common studless link chain was used in this paper. Based on the Miner fatigue cumulative damage rule, S-N curves of chains, and MOSES software, a highly reliable mooring system was designed and analyzed. The calculation results show that the mooring system designed is reliable throughout a 10-year period. It can completely meet the design requirements of American Petroleum institution (API). Therefore, the presented research is significant for advancing the design of this kind of power station.

Keywords

floating tidal current power station / mooring system / mooring chain / fatigue analysis