Interest in the use of composite materials is increasing due to the urgent need to improve and harden our infrastructure, combined with the pending infrastructure bill. Pilot and prototype efforts demonstrate the advantages of factory-produced rapidly-installed lightweight composite bridge decks. The composite technology and the fabrication method facilitate structural health monitoring using low-cost embedded sensors and fiber optics. This session will detail installation of the first composite bridge deck in Tennessee. Results of the project will be presented, with a focus on the ongoing structural health monitoring, embedded sensors, and the outlook for standard installation.
Recent advancements in fiber optic manufacturing, sensor design, and fiber optic interrogators have provided significant opportunities towards the development of cross-cutting fiber optic sensing solutions across the nuclear industry. The addressable harsh nuclear environment markets include Gen II, II+ and IV nuclear reactors, fusion reactors, and accelerator systems. In this work the authors present a series of developments towards the implementation of singlefiber, multipoint, temperature and pressure sensors, test results in high-temperature and high-radiation environments, cryogenic environments, material compatibility studies for sensor packaging, and future development needs to address technical challenges towards sensor commercialization.
In the nuclear industry, there is a need for sensors that are resistant to both high temperatures and radiation. Fiber Bragg gratings inscribed into radiation resistant fibers are a potential solution to this as the femtosecond-infrared laser can inscribe Bragg gratings into fibers without a photosensitive core. In order for these gratings to be used for sensing, they need to be characterized to determine their temperature and radiation response and sensitivity. This paper characterized three commercially available fibers for use in high heat and high radiation environments. There are six fiber variants examined in this study. Three basic fiber designs are investigated: a germanium doped core, a germanium doped core with fluorine cladding, and a fluorine doped core and cladding. For each fiber design, normal and pre-irradiated versions are investigated. The fibers were tested for thermal response by heating them to 1000C and holding for 24 hours, and for radiation resistance by irradiating with gamma radiation. The germanium core doped fibers were more resistant to thermal effects but still had a wavelength shift during the 24-hour soak. The fluorine-doped fibers either had the gratings partially or completely erased during the thermal hold at 1000°C, but showed suitability for short term excursions to this temperature. The radiation data showed significant shifts in some cases, but there was not enough data to form a definitive conclusion. It appears that radiation introduces variability in the response of the Fiber Bragg Gratings (FBG).
Optical Frequency Domain Reflectometry (OFDR) is the basis of an emerging high-definition distributed fiber optic
sensing (HD-FOS) technique that provides an unprecedented combination of resolution and sensitivity. We examine
aerospace applications that benefit from HD-FOS, such as for defect detection, FEA model verification, and structural
health monitoring. We describe how HD-FOS is used in applications spanning the full design chain, review progress
with sensor response calibration and certification, and examine the challenges of data management through the use of
event triggering, synchronizing data acquisition with control signals, and integrating the data output with established
industry protocols and acquisition systems.
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