Modelling of Synthetic Fibre Rope Mooring for Floating Offshore Wind Turbines
Fibre ropes offer beneficial properties for mooring of floating offshore wind turbines (FOWTs). However, the mooring line’s stiffness is both load-history and load-rate dependent. A quasi-static stiffness is observed for slow loading, with a higher stiffness related to rapid, cyclic loading (dynamic...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-01-01
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| Series: | Journal of Marine Science and Engineering |
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| Online Access: | https://www.mdpi.com/2077-1312/11/1/193 |
| _version_ | 1827624268215615488 |
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| author | Stian H. Sørum Nuno Fonseca Michael Kent Rui Pedro Faria |
| author_facet | Stian H. Sørum Nuno Fonseca Michael Kent Rui Pedro Faria |
| author_sort | Stian H. Sørum |
| collection | DOAJ |
| description | Fibre ropes offer beneficial properties for mooring of floating offshore wind turbines (FOWTs). However, the mooring line’s stiffness is both load-history and load-rate dependent. A quasi-static stiffness is observed for slow loading, with a higher stiffness related to rapid, cyclic loading (dynamic stiffness). Design standards provide different guidelines for how to combine these in the mooring analysis. This paper describes procedures for adapting laboratory test stiffness results to the Syrope and a bi-linear model and investigates the consequence of using the models for load calculations. The Syrope model accounts for the quasi-static and permanent rope elongation, while performing the analyses with the dynamic stiffness. The bi-linear model applies both the quasi-static and dynamic stiffness in the dynamic analyses. Based on fibre rope tests performed by Bridon-Bekaert, a Syrope model and two bi-linear models are adapted to the same fibre rope. Fatigue damage and ultimate loads on the mooring lines of Saitec’s SATH FOWT are calculated. The bi-linear model artificially reduces the tension ranges, particularly if there is a large difference between the quasi-static and dynamic stiffness of the fibre rope. This leads to a longer predicted fatigue lifetime. Differences in the extreme loads are caused by the permanent elongation of the Syrope model. This may be countered if the elongation is known and included in the bi-linear model. Finally, the bi-linear model introduces an amplitude-dependency in the horizontal natural periods. |
| first_indexed | 2024-03-09T12:05:22Z |
| format | Article |
| id | doaj.art-1db2d42e58ce419fb66a085301f54c0f |
| institution | Directory Open Access Journal |
| issn | 2077-1312 |
| language | English |
| last_indexed | 2024-03-09T12:05:22Z |
| publishDate | 2023-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Journal of Marine Science and Engineering |
| spelling | doaj.art-1db2d42e58ce419fb66a085301f54c0f2023-11-30T22:58:28ZengMDPI AGJournal of Marine Science and Engineering2077-13122023-01-0111119310.3390/jmse11010193Modelling of Synthetic Fibre Rope Mooring for Floating Offshore Wind TurbinesStian H. Sørum0Nuno Fonseca1Michael Kent2Rui Pedro Faria3SINTEF Ocean, NO-7093 Trondheim, NorwaySINTEF Ocean, NO-7093 Trondheim, NorwayBridon-Bekaert, Coatbridge ML5 2AG, UKBridon-Bekaert, Coatbridge ML5 2AG, UKFibre ropes offer beneficial properties for mooring of floating offshore wind turbines (FOWTs). However, the mooring line’s stiffness is both load-history and load-rate dependent. A quasi-static stiffness is observed for slow loading, with a higher stiffness related to rapid, cyclic loading (dynamic stiffness). Design standards provide different guidelines for how to combine these in the mooring analysis. This paper describes procedures for adapting laboratory test stiffness results to the Syrope and a bi-linear model and investigates the consequence of using the models for load calculations. The Syrope model accounts for the quasi-static and permanent rope elongation, while performing the analyses with the dynamic stiffness. The bi-linear model applies both the quasi-static and dynamic stiffness in the dynamic analyses. Based on fibre rope tests performed by Bridon-Bekaert, a Syrope model and two bi-linear models are adapted to the same fibre rope. Fatigue damage and ultimate loads on the mooring lines of Saitec’s SATH FOWT are calculated. The bi-linear model artificially reduces the tension ranges, particularly if there is a large difference between the quasi-static and dynamic stiffness of the fibre rope. This leads to a longer predicted fatigue lifetime. Differences in the extreme loads are caused by the permanent elongation of the Syrope model. This may be countered if the elongation is known and included in the bi-linear model. Finally, the bi-linear model introduces an amplitude-dependency in the horizontal natural periods.https://www.mdpi.com/2077-1312/11/1/193floating offshore wind turbinessynthetic mooring linesquasi-static stiffnessdynamic stiffness |
| spellingShingle | Stian H. Sørum Nuno Fonseca Michael Kent Rui Pedro Faria Modelling of Synthetic Fibre Rope Mooring for Floating Offshore Wind Turbines Journal of Marine Science and Engineering floating offshore wind turbines synthetic mooring lines quasi-static stiffness dynamic stiffness |
| title | Modelling of Synthetic Fibre Rope Mooring for Floating Offshore Wind Turbines |
| title_full | Modelling of Synthetic Fibre Rope Mooring for Floating Offshore Wind Turbines |
| title_fullStr | Modelling of Synthetic Fibre Rope Mooring for Floating Offshore Wind Turbines |
| title_full_unstemmed | Modelling of Synthetic Fibre Rope Mooring for Floating Offshore Wind Turbines |
| title_short | Modelling of Synthetic Fibre Rope Mooring for Floating Offshore Wind Turbines |
| title_sort | modelling of synthetic fibre rope mooring for floating offshore wind turbines |
| topic | floating offshore wind turbines synthetic mooring lines quasi-static stiffness dynamic stiffness |
| url | https://www.mdpi.com/2077-1312/11/1/193 |
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