Distributed damage detection of offshore steel structures using plastic optical fibre sensors

• Graded index POF distributed sensor used for crack detection in tubular steel tubes.
• Choice of adhesive affects POF crack sensitivity.
• Serpentine configuration of POF sensor able to monitor crack growth.
• Location of crack site detectable to within 10 mm accuracy.

In this paper, results demonstrating the potential application of plastic optical fibre (POF) sensors for damage detection of offshore steel structures are summarized. Graded-index perfluorinated plastic optical fibre (GIPOF) was used for crack detection in tubular steel specimens. A high-resolution photon-counting optical time-domain reflectometer (ν-OTDR) was used for interrogating the optical signal. The study will show that the technique adopted in this study is able to determine the position of the crack in the host structure with high accuracy and repeatability. The technique was also found to be capable of monitoring crack growth in the steel specimens used based on a serpentine sensor configuration.