Investigation On Snap Tension And Fatigue Damage Of Taut-wire Mooring Lines In Deep Water

With the increasing energy demand of human society,it is an irreversible trend to face the development of land resources,energy development from the inland to the deep sea is an irreversible trend.At present,the competition for marine resources is becoming more and more fierce.In order to maintain the high speed development of society,economy and science and technology,the technology of energy exploration and development can not be left behind.This paper introduces two types of mooring system,the scope of application,advantages and disadvantages of cable material characteristics and makes a contrast for anchoring-taut wire mooring system system adapted to the field of deep-sea mooring mooring tension properties and fatigue reliability studies.Study of using the lumped mass method of discrete mathematical model of mooring lines,the cable will be discrete for multi sections connected mass unit.The simulation of motion process by single sine method,to study the trajectory of the cable,the cable tension of three kinds of linear and nonlinear motion condition to do a comparative analysis,effect of elastic modulus of tension,excitation frequency,excitation amplitude,damping coefficient,drag cable and three type mooring in the upper and lower ends of the steel chain length and other factors on the dynamic tension and impact load.The results show that: only in taut slack state will appear under the impact load,the nonlinear and the cable tension is much larger than the linear tension,while the other two conditions are similar,the impact load cable only in considering the nonlinear characteristics of cable and meet certain conditions will occur;found in no impact occurs when a the linear relationship between the elastic modulus of the cable tension and the dynamic excitation amplitude and cable,and impact load,the relation is nonlinear;also found that only the density close to the density of seawater,the dynamic tension of mooring line will appear in the impact load.Based on ANSYS simulation software,a semi submersible platform model was built with "offshore oil 981" as an example,and the Aqwa module was designed to design a taut mooring system with a water depth of 1500 m.In the short term sea No.44 as an example,the motion response of the semi submersible platform and cable tension parts are studied,based on the MATLAB program is developed to calculate fatigue fatigue damage analysis of mooring cable theory,and with the help of this procedure to calculate the fatigue damage of polyester fiber cable hybrid cable in the top.