Implementation and Verification of Cable Bending Stiffness in MoorDyn

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5 Scopus Citations

Abstract

The relatively large motions experienced by floating wind turbines and wave energy converters pose a challenge for power cables, whose internal components provide significant bending resistance and are sensitive to deformation. The behavior and associated design considerations of power cables in these highly dynamic applications make coupled analysis relevant for design. Bending stiffness capabilities have recently been added to the lumped-mass mooring dynamics model MoorDyn to enable simulation of dynamic power cables. MoorDyn is a common modeling choice for floating wind energy simulation (often coupled with OpenFAST) and floating wave energy converter simulation (often coupled with WEC-Sim) but the model's previous line elasticity formulation only considered axial stiffness. To properly capture the dynamics of power cables, a bending stiffness model has been added that approximates cable curvature based on the difference in tangent vectors of adjacent elements. The resulting bending moment is realized by applying forces on adjacent nodes, enabling cable modeling while leaving the underlying lumped-mass formulation unchanged. In this paper, the new bending stiffness implementation is verified in static conditions against analytical solutions and then in a dynamic power cable scenario in comparison with the commercial simulator OrcaFlex. The dynamic scenario uses prescribed motions and includes wave loadings on the cable. Results indicate correct implementation of bending stiffness and show close agreement with OrcaFlex.

Original languageAmerican English
Number of pages6
DOIs
StatePublished - 2021
EventASME 2021 3rd International Offshore Wind Technical Conference, IOWTC 2021 - Virtual, Online
Duration: 16 Feb 202117 Feb 2021

Conference

ConferenceASME 2021 3rd International Offshore Wind Technical Conference, IOWTC 2021
CityVirtual, Online
Period16/02/2117/02/21

Bibliographical note

See NREL/CP-5000-76968 for preprint

NREL Publication Number

  • NREL/CP-5000-80089

Keywords

  • Bending stiffness
  • Cable dynamics
  • Dynamic cable
  • Lumped mass
  • MoorDyn

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