Towards passive ultrasonic sounding of a steelconcrete-steel containment structure using embedded optical fibers
Résumé
We present a Steel-Concrete wall model equipped with several embedded fiber Bragg Gratings (FBGs) and several embedded and surface piezoelectric accelerometers (PZAs). We compare the performances of these embedded sensors for several ultrasonic sources disposed on the surface of the wall and emitting at frequencies between a few tens and a few hundreds of kilohertz. We observed that a significant part of the wave energy can be transmitted to the concrete through the surface liner, despite the high mechanical contrasts between steel and concrete. Using a collection of random hammer impacts applied on the steel surface, we further attempted to reconstruct empirical Green's functions between pairs of sensors buried into the structure using passive seismic methods.