Underwater acoustic emission monitoring – Experimental investigations and acoustic signature recognition of synthetic mooring ropes

Imran Bashir, Jodi Walsh, P. R. Thies, Sam Weller, Philippe Blondel, Lars Johanning

Research output: Contribution to journalArticle

5 Citations (Scopus)
117 Downloads (Pure)

Abstract

Mooring ropes are essential components of offshore installations, and synthetic ropes are increasingly preferred because of their favourable cost to weight ratios. In-service condition of these materials is traditionally monitored through costly visual inspection, which adds to the operating costs of these structures.
Acoustic Emissions (AE) are widely used for condition-monitoring in air, and show great potential underwater. This paper investigates the AE signatures of synthetic mooring ropes subjected to sinusoidal tension-tension loading in a controlled environment, using a large-scale dynamic tensile test rig. With a linear array of 3 broadband (20 Hz to 50 kHz) hydrophones, four main signatures are identified: low-to high frequency, low-amplitude signals (50 Hz to 10 kHz), low-amplitude broadband signals (10 kHz to 20 kHz), high amplitude signals (10 Hz to 48 kHz) and medium-amplitude signals (500 Hz to
48 kHz). These AE types are related to different stages of rope behaviour, from bedding-in to degradation and failure. The main findings are that the failure location and breaking load can be identified through the detection of AE. The occurrence of high amplitude AE bursts in relation to the applied tensile load allows the detection of an imminent failure, i.e. prior to the failure event. These initial results indicate that AE analyses can enable the integrity of synthetic mooring ropes to be monitored
Original languageEnglish
Pages (from-to)95-103
Number of pages9
JournalApplied Acoustics
Volume121
Early online date16 Feb 2017
DOIs
Publication statusPublished - Jun 2017

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Keywords

  • Acoustic Emissions
  • Mooring ropes
  • Wave Energy Converters
  • Condition monitoring
  • Reliability
  • Marine renewable energy
  • underwater acoustics

ASJC Scopus subject areas

  • Acoustics and Ultrasonics
  • Ocean Engineering
  • Renewable Energy, Sustainability and the Environment

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