Numerical study of rope materials of the mooring system for gravity cages.

A numerical model is developed to compare the performances of mooring materials for a gravity cage system. At first, a small-scale model is built and it is validated by the previous experiments. With the same method, a full-scale gravity cage model is built to study the performance of different mooring materials. Link elements are used to model the wire ropes to consider the weight, and nonlinear spring elements are used to model the composite fibre ropes to consider the nonlinear stiffness. High-tenacity polyester multifilament fibre has the best performance. It can reduce the average value and amplitude of the mooring forces, which also contributes to reducing the stress concentration on the collar. At last, the mooring forces at specific locations in Portugal are calculated and the distributions of mooring force amplitudes are analysed. • A numerical model is developed to compare the performances of mooring materials for a gravity cage system. • A small-scale model is built and it is validated by the previous experiments. • With the same method, a full-scale gravity cage model is built to study the performance of different mooring materials. • Wire ropes and composite fibre ropes are studied and are modelled considering the nonlinear stiffness. • High-tenacity polyester multifilament fibre has the best performance as it can reduce the mooring forces. [ABSTRACT FROM AUTHOR]