ABSTRACT
The mooring system is a system for maintaining a floating object such as a ship in a fixed position. For the design of the mooring system, the dynamic, coupled analysis of the ship and the mooring system should be performed in advance. Traditionally, the FEM (Finite Element Method) has been adopted to model the mooring system connected to a single body such as the ship. However, it is not applicable for a multibody system such as two ships in tandem offloading. In this study, mooring lines are modeled by one-dimensional flexible body which is composed of several nodes and elements. Also, the flexible multibody dynamics is used to solve the equations of motion of the multibody system (ships, mooring lines, etc.) without any iteration. Furthermore, the interactions between the system such as collision and friction are considered. For the collision, the non-interpenetration constraints are adopted, and the holding power of an anchor is also taken into account. Finally, the dynamic, coupled analysis of the mooring system connected to an LNG FPSO and an LNG carrier in tandem offloading is performed. As a result, we obtained the optimized design of the mooring system which is satisfied with the guidelines for the mooring design such as OCIMF (Oil Companies International Marine Forum).
