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Distributed Fibre Optic Sensors for Stiffened Skin Panels Strain Monitoring and Failure Mode Detection



Three composite stiffened panels of 1300 mm x 600 mm manufactured by Resin Liquid Infusion were tested until failure. Two of these panels are representative of a wing skin reinforced with stringers and were tested under compression. The third panel, with two stringers and a manhole, was tested under tension and compression loads. In order to perform the structural tests, each panel is instrumented with strain gauges and advanced methods for strain monitoring, such as photogrammetry and optical fiber sensors. The distributed sensing technique has been chosen because it allows a huge number of sensors along the fiber length with high spatial resolution and strain accuracy. Several optical fibers were bonded onto the surface of the stringer covering the full surface and the stringers in order to analyze the strain fields. The strain all along the fiber length was obtained with the OBR and compared with strain gages. In order to identify the failure mode each distributed measurement line is analyzed to localize failure initiation points. From the obtained results it has been shown that the distributed measurement technique can be used to locate the initiation point before fatal failure of the panel.

doi: 10.12783/SHM2015/380

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