A Global Shape Function Method for Dynamic Analysis of Mooring Systems

A new global shape function (GSF) based dynamic analysis method for mooring systems of floating structures is proposed, aiming at securing a robust solution to the existing trade-off issue between accuracy and efficiency. Distinguished from the widely used methods, the GSF method is initially derived from Hamilton’s principle, and then the global stiffness matrices are directly constructed under the consideration of global nonlinear strain with the capability of high-computational efficiency, owing to the unemployment of transformation matrices. Each mooring line is discretized into elements using Lagrangian shape functions, which deliberately consider both the Morison forces and the time-varying global stiffness matrices in a set of control equations. The accuracy of the proposed GSF method is firstly verified by experimental results published. Results show that the GFS method has the ability to achieve more accurate results than the solutions of the rod theory applicable to dynamic analysis of the mooring system. Furthermore, an OC4 floating wind turbine is employed to demonstrate at least 35% efficiency improvement than the results by the rod theory, while maintaining the same accuracy. This study sheds light on potential applications in marine engineering.