Research on the Viscoelasticity of Polyester Mooring Lines Using the Absolute Nodal Coordinate Formulation

Abstract

The taut mooring system using synthetic fiber ropes has overcome the shortcomings such as the large self-weight of the mooring lines and provides better mooring performance for the floating structures. The polyester rope has attracted much attention among numerous synthetic fiber rope materials due to its lightweight, low price, corrosion resistance, and high strength. Thus, the mooring characteristics of it are worth studying. Polyester mooring lines are flexible in deep water, when a marine structure is moored by them, the geometric nonlinearity such as large displacement, large stretch, and large bending deformation, and the material nonlinearity like viscoelastic of the polyester ropes become complex integrated problems to be studied. Considering the nonlinear phenomenon, the simulation and calculation of a polyester line were carried out by the absolute nodal coordinate formulation (ANCF) in this paper since the ANCF method has advantages in dealing with the significant deformation problems of the flexible structures. In addition, a chain mooring line was also simulated for comparison, and the results show that the polyester ropes reduce the self-weight of the mooring lines and provide sufficient mooring strength at the same time, and the nonlinear phenomenon of the polyester ropes is different from that of the chain mooring lines.

Keywords

Taut mooring / Polyester rope / Absolute nodal coordinate formulation / Viscoelasticity / Chain mooring line / Geometric nonlinearity / Material nonlinearity