Damage assessment and monitoring of composite ship joints

This paper describes the research activities associated with the damage assessment of maritime structures, conducted within the Cooperative Research Centre for Advanced Composite Structures, which aims to develop the capability to predict the criticality of typical damage in a ship joint and to develop and test techniques for its structural health monitoring (SHM). The research is focused on modelling and testing of a typical monolithic glass fibre reinforced polymer composite T-joint, which is subjected to disbonds at various interfaces. Methods for determining critical disbond sizes and two semi empirical methods have been evaluated. Embedded optical fibre Bragg grating sensors have been assessed for SHM. Issues have been addresses, involving embedding optical fibres into the joint interface and a technique has been developed for successful embedding and positioning of sensors. The performance of embedded Bragg grating sensors in such joints has been shown to be satisfactory and the effects of artificially induced disbonds on the strain distribution have been determined via finite element modelling and have been experimentally verified. The use of the random decrement signature of the structural response to turbulence has been assessed for SHM. Models and experiments involving typical joints with artificially induced disbonds have indicated that this technique could be successfully used to detect and characterise damage.