An enhanced stiffness model for elastic lines and its application to the analysis of a moored floating offshore wind turbine

Lin, Zi and Sayer, Philip (2015) An enhanced stiffness model for elastic lines and its application to the analysis of a moored floating offshore wind turbine. Ocean Engineering, 109. pp. 444-453. ISSN 0029-8018

Lin_Sayer_OE_2015_An_enhanced_stiffness_model_for_elastic_lines_and_its_application_to_the_analysis.pdf - Accepted Version
Available under License Creative Commons Attribution Non-commercial No Derivatives 4.0.

Download (1MB) | Preview
Official URL:


The performance of a polyester mooring line is non-linear and its elongation plays a significant role in the dynamic response of an offshore moored structure. However, unlike chain, the tension–elongation relationship and the overall behavior of elastic polyester ropes are complex. In this paper, by applying an enhanced stiffness model of the mooring line, the traditional elastic rod theory has been extended to allow for large elongations. One beneficial feature of the present method is that the tangent stiffness matrix is symmetric; in non-linear formulations the tangent stiffness matrix is often non-symmetric. The static problem was solved by Newton–Raphson iteration, whereas a direct integration method was used for the dynamic problem. The computed mooring line tension was validated against the proprietary OrcaFlex software. Results of mooring line top tension predicated by different elongations are compared and discussed. The present method was then used for a simulation of an offshore floating wind turbine moored with taut lines. From a comparison between linear and non-linear formulations, it is seen that a linear spring model under-estimates the mean position when the turbine is operating, but over-estimates the amplitude of the platform response at low frequencies when the turbine has shut down.

Item Type: Article
Uncontrolled Keywords: Dynamic response, Motion response, Mooring system, Finite element method, Elastic rod theory, Large extension
Subjects: H100 General Engineering
H300 Mechanical Engineering
H500 Naval Architecture
H900 Others in Engineering
Department: Faculties > Engineering and Environment > Mechanical and Construction Engineering
Depositing User: Rachel Branson
Date Deposited: 05 Aug 2020 08:53
Last Modified: 31 Jul 2021 12:05

Actions (login required)

View Item View Item


Downloads per month over past year

View more statistics