Health monitoring of marine composite structural joints using fibre optic sensors

This paper describes a methodology for the health monitoring of composite marine joint structures based on strain measurements under operational loading using embedded fibre Bragg grating sensors. Finite element modelling indicated that the presence of a disbond significantly altered the bond-line longitudinal strain distribution. This was verified qualitatively through an experimental test program. The experimental results are examined in relation to the FE predictions and the implications for a practical strain-based SHM system are discussed. A technique is developed, based on novel signal processing and statistical outlier detection. This enables the sensor measurements to be used for damage detection without reference to a high-fidelity numerical model of the structure which is often difficult and resource-intensive to generate. The technique is shown to provide successful damage diagnoses with an acceptable level of accuracy. Further improvement in diagnostic accuracy may be achieved by increasing the sensor density.