Fatigue Analysis of the Taut-Wire Mooring System Applied for Deep Waters

• Published in: China ocean engineering Vol. 25; no. 3; pp. 413 - 426
• Main Author: 黄维 刘海笑 单桂敏 胡存
• Format: Journal Article
• Language: English
• Published: Heidelberg Chinese Ocean Engineering Society 01.09.2011; School of Civil Engineering, Tianjin University, Tianjin 300072, China
• Subjects: Coastal Sciences; Deep water; Dynamical systems; Dynamics; Engineering; Fatigue (materials); Fatigue failure; Fatigue life; Fluid- and Aerodynamics; Marine; Marine & Freshwater Sciences; Mooring; Numerical and Computational Physics; Oceanography; Offshore Engineering; Polyester resins; Simulation; 动态刚度; 应用; 深海; 疲劳分析; 疲劳寿命预测; 系泊系统; 紧线; 线路故障; fatigue analysis; T-N curve; dynamic stiffness; one-line failure; taut-wire mooring system; pre-tension
• ISSN: 0890-5487; 2191-8945
• DOI: 10.1007/s13344-011-0034-5

Precisely predicting the fatigue life of taut-wire mooring systems has become an interesting and important problem for scientists and engineers since there are still difficulties in the inspection and maintenance of mooring lines in a rough sea environment especially in deep waters. In this paper, a comprehensive fatigue analysis is performed for a polyester taut-wire mooring system of an FPSO based on the time domain dynamic theory, rainflow cycle counting method and linear damage accumulation rule of Palmgren-Miner. Three influential factors in the fatigue analysis including the pre-tension, dynamic stiffness and T-N curve are investigated in detail. Two polyester T-N curves, one is from the DNV- 0S-E301 and the other is from the API-RP-2SM, are adopted in the calculation. The fatigue analysis of the mooting system after one-line failure is also carried out. The calculation results indicate that the fatigue life is significantly affected by the T-N curve. The fatigue life decreases with increasing pre-tension, and is largely reduced if taking into account the dynamic stiffness caused by cyclic loading. The analysis also proves that one-line failure has remarkable effects on the fatigue lives of other mooting lines. The present parametric and comparative study is believed to be meaningful to further understanding of the taut-wire mooting system for deepwater applications.