Structural health monitoring has become more and more popular in application of damage diagnosis and safety assessment. Optical fiber sensors, as one of the most efficient sensing elements, for the superior advantages of long-term stability and durability, good geometrical shape-versatility, corrosion resistance and anti-electromagnetic interference, are widely used in diverse technological fields. Measurement precision of the sensor is thus emphasized and strain transfer analysis put forward to explain the action mechanism and improve the test accuracy. Theoretical derivation on strain transfer error analysis of optical fiber sensor applied to structure with local debonding interface is carried out in this paper. Cases that optical fiber sensors are bonded on the surface of structure and embedded in structure are discussed, respectively, and related error modification functions are provided. The research is meaningful for improving the precision of optical fiber sensors applied to structures with the existing of local debonding interface, which will be ultimately serve for showing true mechanical state of structures.
The large span and heterogeneous components of multi-layered pavement structure usually bring about stochastic damage, and many modern approaches, such as ground penetrating radar, integral imaging and optical fiber sensing technology, have been employed to detect the degeneration mechanism. Restricted by the cost and universality, novel elements for pavement monitoring are in high demand. Optical fiber sensing technology for high sensitivity, long stability, anti-corrosion and resistance to water erosion then is considered. Therefore, a movable FBG sensor located in flexible pipe is developed, which has long stroke inside inner wall of the hollow pipe, and a full-scale shape of the structure could be sketched just with one FBG. Theoretical and experimental methods about establishing the relationship between wavelength variable and curvature have been provided, and function about reconfiguring the coordinate is converted to a mathematic question. Move over, transfer error modification has been taken into account for modify related error. Multi-layered pavement model embedded with this sensor will be accomplished to inspect its performance in later work. The work in the paper affords a feasible method for shape monitoring and would be potentially valuable for the maintenance and inverse design of pavement structure.
Technology on pavement monitoring has been paid more and more attention by government, engineers
and scholars. Conventional methods, such as artificial inspection and core sampling, have defect in low
efficiency and limited coverage, and modern technologies, such as spectrum analysis and integral
imaging, have poor resistance to external interference and high cost, which reveals that common
approaches have fallen behind the development of road engineering. Therefore, a novel raw
material-encapsulated FBG strain sensor is put forward, thinking over outstanding advantages of fiber
Bragg grating and perfect incorporation between coating layers and host layers. Numerical analysis and
experiments have been done to inspect behavior of the sensing system. Results indicate that it can well
detect the actual performance of pavements, and the sensor presents a high-precision, real-time and
long-term monitoring, owning function of road disaster warming, which promise it an extensive future
in pavement monitoring.