Investigating polymer fibre optics for condition monitoring of synthetic mooring lines

Tessa Gordelier*, Phillip Rudolph Thies, Giovanni Rinaldi, Lars Johanning

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Synthetic mooring lines are becoming a popular alternative to conventional chain mooring systems. For marine renewable energy devices, they have been considered as an enabling technology for this nascent sector, given their reduced costs and ease of deployment. However, the extreme operating environment has led to an increased interest in the 'in-situ' condition monitoring of these mooring lines. This paper considers the use of polymer fibre optic technology and the optical time domain reflectometry (OTDR) technique for the condition monitoring of synthetic mooring lines. To establish the operating envelope of the fibres, Polymethylmethacrylate (PMMA) polymer optical fibres are mechanically tested. Additionally, an OTDR is used to monitor fibres whilst under elongation using a tensile test machine, and the sensitivity of the system in monitoring strain is established. At the lowest strain rate, the average proportional limit and yield points of the fibres are found at 1.16% strain and 5.41% strain, respectively. Fatigue exposure of fibres up to 1.25% strain identifies no measurable effect on fibres' proportional limit or yield point. The occurrence of significant creep is identified for fibres strained beyond 1.5%. The OTDR system is able to identify strains at and above 4%. The study identifies important criteria that should be considered in the integration of polymer optical fibres for mooring applications. Limitations are discussed and suggestions for progressing this technology are provided.

Original languageEnglish
Article number103
JournalJournal of Marine Science and Engineering
Volume8
Issue number2
DOIs
Publication statusPublished - 1 Feb 2020

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Water Science and Technology
  • Ocean Engineering

Keywords

  • Condition monitoring
  • OTDR
  • PMMA
  • Polymer optical fibre
  • Reliability
  • Synthetic mooring system

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