Numerical analysis of pitting corrosion fatigue in floating offshore wind turbine foundations

Behrooz Tafazzoli Moghaddam, Ali Mahboob Hamedany, Ali Mehmanparast, Feargal Brennan, Kamran Nikbin, Catrin Mair Davies

Research output: Contribution to journalConference article

Abstract

The mooring system of offshore floating wind foundations, which anchors the floating foundations to the seabed, sustains large dynamic loads during operation. The mooring chains are connected to the floating foundation below the water level through fairleads and chain-stoppers. The corrosive marine environment and the cyclic loading make the mooring connection prone to corrosion pitting and fatigue crack initiation and propagation from the pits, particularly in the weld zones. In this study, a finite element analysis of the crack growth from corrosion pits has been performed and the results are presented in order to provide an estimate of the extent of damage after the crack is detected. A Python script have been developed which generates the pit profiles based on a non-uniform random distribution of pit dimensions. 3D pits and elliptical cracks are embedded at critical points of weldment on the mooring point and analysed using ABAQUS XFEM. The Walker's model has been applied in the model to examine the effect of realistic R ratios in floating structures on pitting corrosion fatigue crack propagation along with direct cyclic solver. The numerical results obtained from this study are discussed in terms of the corrosion pitting effects on fatigue crack propagation behaviour in Spar-type floating offshore wind turbine foundations.

Original languageEnglish
Pages (from-to)64-71
Number of pages8
JournalProcedia Structural Integrity
Volume17
Early online date25 Aug 2019
DOIs
Publication statusE-pub ahead of print - 25 Aug 2019
Event3rd International Conference on Structural Integrity, ICSI 2019 - Funchal, Madeira, Portugal
Duration: 2 Sep 20195 Sep 2019

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Keywords

  • corrosion fatigue
  • extreme value statistics
  • floating offshore wind turbine
  • rainflow cycle counting
  • XFEM

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