Fibre Bragg Grating-Based Acoustic Sensor Array for Improved Condition Monitoring of Marine Lifting Surfaces

Abstract

This paper discusses a novel approach to monitor marine lifting surface conditions through using arrays of Fibre Bragg Grating (FBG)-based acoustic sensors in a marine rudder. Results from these optical sensor arrays are then cross compared with those from conventional piezoelectric (PZT) sensors. A successful proof-of-concept evaluation of the optical sensor approach was, however, first undertaken by using cascaded FBGs integrated into a glass plate, monitoring the response to dropping a standard metal ball at different locations. Data obtained were compared with colocated conventional PZT sensors acoustic sensors for comparison using triangulation to determine the location of the excitation source (a sonotrode). The results obtained verify the excellent performance of the FBG-based sensors due to the excellent agreement between these different sensor types. This gives confidence to the next-stage to scale-up the FBG sensor arrays for other marine structures, with early identification of the initiation of cavitation erosion an important priority for better operational reliability and scheduling of maintenance of marine vessels.