Effects of dynamic axial stiffness of elastic moorings for a wave energy converter
Journal
Ocean Engineering
Journal Volume
251
Date Issued
2022
Author(s)
Abstract
This work studies the effects of the dynamic axial stiffness of elastic moorings on the dynamic behaviour of a point absorber wave energy converter. Following two mooring analysis procedures, coupled dynamic analysis of a taut-moored WEC with three legs is performed using the FEM program DeepC in three irregular wave conditions. Two synthetic fibre rope materials are investigated, i.e. a normally stiff polyester and a wire-lay 3-strand nylon rope. The results of WEC motions and mooring tensions obtained from a quasi-static stiffness model and the dynamic stiffness model are compared and discussed. The former analysis applies the non-linear stiffness working curves of the ropes in the simulations, while the latter utilizes the dynamic stiffness expression with an iterative process following a practical mooring analysis procedure. For the nylon rope, the influence of the load amplitude on the dynamic stiffness and the WEC response is presented and analysed. It was found that the quasi-static stiffness model tends to underestimate the maximum mooring tensions, leading to 30%–40% lower results compared to the one accounting for the dynamic stiffness effects. For the studied WEC system, the nylon rope shows advantages over polyester, because of the lower mooring tensions and higher WEC motions. © 2022 Elsevier Ltd
Subjects
DeepC; Dynamic axial stiffness; Elastic cables; Wave energy converter
Other Subjects
Mooring; Mooring cables; Polyamides; Rayon; Rope; Stiffness; Axial stiffness; Deepc; Dynamic axial stiffness; Dynamic stiffness; Elastic cable; Mooring analysis; Mooring tension; Nylon ropes; Stiffness modeling; Wave energy converters; Wave energy conversion; amplitude; cable; dynamic analysis; mooring system; stiffness; wave energy
Type
journal article