Tension-torsion Coupled Dynamic Response Characteristics And Fatigue Strength Analysis Of Mooring Wire Rope

Under the action of wind,wave and current,floating structures in the ocean move violently and endanger the safety of the operation.The mooring system is the key to ensure the stability and safety of the structure.Due to its own structural characteristics,the wire rope will produce torsion effect and affect the fatigue life.Therefore,it is of great significance for ensuring the safety of mooring and realizing the normal operation of the floating structure to comprehensively consider the tension-torsion coupling characteristics of wire rope.It is significant for studying the mechanical properties of mooring wire rope and analyze the fatigue life under dynamic response.At present,only the tension is considered in the current study,but there are few studies on the tension-torsion coupling characteristics.In this paper,based on the theory of solid mechanics and considering the structural characteristics of the rope,the mechanical balance equation of the rope under the tension-torsion is established.The hertz contact theory is applied to the simulation of wire rope,the solution method of point contact and line contact forces and contact stress is established,the response of different wire ropes under axial load is analyzed,and the relationship between torque and axial force is studied.The fine finite element model of rope is established,the stress and deformation distribution under axial strain are analyzed,and the effect of twist angle on stress is studied.Based on the dynamics theory,the equations of rope dynamics are established by considering the action of wave currents and the bending,stretching and torsion of the rope.The law of torsion effect on the dynamic internal force of the rope is studied.The S-N curve is used to analyze the fatigue life of the rope.The influence of programming type and different excitation conditions on the life is studied.The influence of rope breakage is analyzed,and the failure mechanism of the rope under extreme load is explored.Based on a large number of numerical simulation and research work,put forward the suitable for preparation of different type of analytical model and finite element model of wire rope under tension-torsion coupling obtained characteristics of the dynamic response of the mooring line,and considering the incentive effect,it is concluded that the structural type of influence on fatigue life,the paper conclusion for the paper work for ocean engineering in the mooring has guiding significance for design and fatigue analysis.