Dynamic Response of Different Types of Mooring Wire Ropes

Given that the torsion characteristics of rope have seen little research domestically,in this paper,tension-torsion models of different types of wire ropes were established. The basic characteristics of wire rope structure and steel wire material were analyzed,including the force of wire ropes in marine engineering. Based on reasonable assumptions,the stress distribution of wire ropes was simplified into a geometric problem,and the response characteristics of wire ropes under the joint action of tension and torsion were determined. In view of the different contact characteristics between steel wires,the Hertz contact theory was incorporated into numerical simulation of wire ropes,and the method of contact stress solutions of point and line contact was established. Based on the theory of nonlinear dynamics,the coupling terms of tension,bending and torsion were introduced into the stiffness of wire ropes,and the equations of dynamic equilibrium were derived. A model for the calculation of a mooring system was established to obtain the rope dynamic response under the external load. The influence of the torsion of the rope on the tension under axial load was analyzed. The influence of torsion on the internal force of the rope was also studied,and a law of tension variation was established. Study results showed that the response of different types of wire ropes,including the tension value,varied under the same axial load. Compared with the values obtained when torsion was neglected,the tension values calculated for the different rope types were larger and varied by rope type. Cross-sectional stress distribution was not uniform for the different types. The distribution of internal stress in wire rope was closely related to the type of rope,so it is very important to consider the specific type in the calculation of stress,especially in the analysis of contact stress. The 6×19 type had a lower response when subjected to external load due to the alternating arrangement of left and right twisting. © 2020, Editorial Board of Journal of Tianjin University(Science and Technology). All right reserved.