| With the optimization of international energy structure, the proportion of various types of new energy in the energy consumption structure system is becoming larger and larger. At the same time, in the environment of the increasingly fierce competition in the marine resources, the measure of wave environment and the communication in far-reaching sea area is also more important. In the field of deep sea mooring system, the taut-wire mooring system based on polyester has been widely used, and this mooring material has special dynamic stiffness and fatigue characteristics. In this paper, based on the sufficiently exploring on the design status of deepwater mooring system and research method of fatigue reliability problems,the taut-wire and catenary mooring system are respectively designed for the communication platform which serves in South China Sea, integrate new energy and communication together. And then the fatigue life of the taut-wire and catenary mooring system as well as the fatigue reliability of the former are calculated, so as to obtain some useful conclusions.Firstly, the rain flow counting method has been write so as to handle the time domain data and gain the tension range and cycle times. After that, AQWA software is used to build the hydrodynamic model of platform and do time domain analysis,then the most dangerous direction of environment load and high damaged mooring line is chosen to simplify the calculation of fatigue life. Then iterative dynamic stiffness calculation of taut-wire mooring system to get the final value of stiffness,and calculate fatigue damage of polyester rope by time-domain method which is used in this case as well as joint spectrum method in the specification of API respectively and compare the results, the calculation shows that time domain method is workable to this case. Then under premise of the same relationship between tension and the distance to static equilibrium position close to the canal chock, the taut-wire mooring system as well as catenary mooring system are designed. After that, the total fatigue damage and fatigue life are calculated. Finally the results are compared and analyzed, it is considered the fatigue properties of synthetic fiber cable is greater than steel chain in this case.In fatigue reliability analysis, according to treatment methods in marine engineering fatigue analysis which is commonly used that the variables are assumed to obey the lognormal distribution, and obtain the stress of the mean square value and zero crossing rate according to the rain flow counting method to calculate the fatigue reliability index of the taut-wire mooring system. The study shows that thetaut-wire mooring system has a high reliability for 20 years’ design life. |
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