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An embedded Fiber Bragg Grating (FBG) strain sensor and an FBG temperature sensor have been shown to be able to accurately monitor the industrial composite cure process of a glass/ epoxy plate devoted to aeronautical applications. The internal absolute strain level in the plate was determined, free of temperature effect thanks to a differential method. After curing, a residual compression strain of about -0.22% was observed, which represents a short part of the range in compression for a single mode fiber. Later on, the embedded FBG strain sensor could be used as a smart sensor for the health monitoring of composite structures, e.g. for impact or layer delamination detection.

Embedded distributed micro/macro-bending multimode optical fiber transducers multiplexed in the time domain (photon counting, optical time domain reflectometry) and quasi-distributed embedded in-fiber Bragg grating (FBG) filters based on wavelength measurement and demultiplexing encoding have been used for damage detection assessment in a radome sandwich structure. Both methods are well suited for detection and localization of permanent damage induced by impacts of energy ranging from 8-20 J. Optical fiber sensor measurements have been compared to those given by classical health monitoring methods using ultrasonics and shearography, as well as infrared thermography.

The main purpose of the experiments described here is the analysis of the mechanisms of radome protection with lightning diverters of various types and sizes. A high voltage arrangement and associated diagnostics have been implemented to perform a quantitative study of the inception and propagation mechanisms of the corona and leader discharges that precede the final breakdown. It is shown that ambient humidity plays a significant role on the discharge process and that the nature of the discharge initiated from the strip is very different depending on the strip type. Segmented strips are more likely to allow energetic discharges to propagate from an internal antenna leading to radome puncture.