Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Fitness-for-purpose assessment of cracked offshore wind turbine monopile
Abstract In this paper, the procedure for flaw acceptability assessment is examined through a case study of a semi-elliptical surface crack in an offshore monopile as it grows till it forms a through thickness crack. Using the procedure prescribed in an industrial standard (BS 7910), the fracture ratio, Kr is shown to increase monotonically with increasing crack depth. The load ratio, Lr, is initially insensitive to the crack depth. However, there is a rapid increase in Lr when the crack depth to thickness ratio exceeds 80%. Lr values obtained from detailed 3D FE limit analysis using elastic-perfectly-plastic material behaviour do not exhibit the asymptotic behaviour predicted by BS 7910 as the flaw transitions from deep crack to through-thickness crack. Furthermore, Kr predicted by BS 7910 is shown to be an over-estimation for the typical dimensions of offshore monopiles. The findings suggest that a structure with a deep flaw may be identified as unacceptable based on BS 7910 when it may still possess a non-trivial amount of structural residual life. This is a concern for monopiles where crack growth as a large flaw forms a significant part of the total life.
Highlights Evaluation of the acceptability of a known flaw in an offshore wind turbine monopile. Examination of crack behaviour at transition of surface crack to through thickness crack. Description of limit load finite element analysis for offshore wind turbine monopile. Comparison of BS 7910 flaw acceptability procedure to finite element analysis results.
Fitness-for-purpose assessment of cracked offshore wind turbine monopile
Abstract In this paper, the procedure for flaw acceptability assessment is examined through a case study of a semi-elliptical surface crack in an offshore monopile as it grows till it forms a through thickness crack. Using the procedure prescribed in an industrial standard (BS 7910), the fracture ratio, Kr is shown to increase monotonically with increasing crack depth. The load ratio, Lr, is initially insensitive to the crack depth. However, there is a rapid increase in Lr when the crack depth to thickness ratio exceeds 80%. Lr values obtained from detailed 3D FE limit analysis using elastic-perfectly-plastic material behaviour do not exhibit the asymptotic behaviour predicted by BS 7910 as the flaw transitions from deep crack to through-thickness crack. Furthermore, Kr predicted by BS 7910 is shown to be an over-estimation for the typical dimensions of offshore monopiles. The findings suggest that a structure with a deep flaw may be identified as unacceptable based on BS 7910 when it may still possess a non-trivial amount of structural residual life. This is a concern for monopiles where crack growth as a large flaw forms a significant part of the total life.
Highlights Evaluation of the acceptability of a known flaw in an offshore wind turbine monopile. Examination of crack behaviour at transition of surface crack to through thickness crack. Description of limit load finite element analysis for offshore wind turbine monopile. Comparison of BS 7910 flaw acceptability procedure to finite element analysis results.
Fitness-for-purpose assessment of cracked offshore wind turbine monopile
Fajuyigbe, A. (Autor:in) / Brennan, F. (Autor:in)
Marine Structures ; 77
31.01.2021
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
| Europäisches Patentamt | 2020
Seismic Analysis of Monopile Supported Offshore Wind Turbine
| British Library Conference Proceedings | 2018