NSHT: New Smart Hybrid Transducer for Structural and Geotechnical Applications

Featured Application The proposed work provided a structural transducer able to continuously measure the strain on linear structures in time and space. The transducer has been realized connecting fiber-reinforced tapes and optical fiber sensors. It has been possible, then, to overcome some weaknesses of traditional optical fiber sensors, like fragility and critical positioning, in actual civil structures. The system has been tested in some real scale examples and was shown to satisfy the requirements of easy on-site applications. The feasibility of the sensor and the transducer allow for using it in connection with fiber-reinforced tapes as an integrated system for smart structural reinforcement as well those which can be used for the continuous health monitoring of structures consequent to restoration and repair. This work describes the application of a new transducer prototype for continuous monitoring in both the structural and geotechnical fields. The transducer is synthetically constituted by a wire of optical fiber embedded between two fiber tapes (fiberglass or carbon fiber) and glued by a matrix of polyester resin. The fiber optical wire ends have been connected to a control unit whose detection system is based on Brillouin optical time-domain frequency analysis. Three laboratory tests were carried out to evaluate the sensor's reliability and accuracy. In each experiment, the transducer was applied to a sample of inclinometer casing sets in different configurations and with different constraint conditions. The experimental collected data were compared with theoretical models and with data obtained from the use of different measuring instruments to perform validation and calibration of the transducer at the same time. Several diagrams can compare the transducer and highlight its suitability for the monitoring and maintenance of structures. The characteristic of the transducer suggests its use as a mixed system for reinforcing and monitoring, especially in the lifetime maintenance of critical infrastructures such as transportation and service networks, and historical heritage.