In-situ monitoring of braided composite tubes with optical fibres and piezoelectric sensors

In this work, damage monitoring is achieved by embedding a 10-metre long distributed optical fibre sensor (DOFS) between a thin shell composite tube and subsequent layers of over-braiding. The DOFS provides in situ, discrete strain measurements along its length, allowing full-field monitoring of the braiding, resin infusion, and curing processes. Piezoelectric wafer active sensors (PWAS) surface mounted on the cured composite tube facilitate acoustic emission (AE) monitoring during quasi-static flexural loading of the tube. The two sensing methods combined enable the early detection and recording of damage events in the tube, in real-time, while application of a clustering algorithm to AE data a posteriori shows potential in the classification of signals according to different damage mechanisms.