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Distributed sensors for structural health monitoring of bridges and dams

on January 20, 2020

damsNowadays distributed fiber optic sensors remain a subject of great interest for constant structural health monitoring of huge structures, for instance, bridges or dams. Herewith, the more sensing points there are, the more effective monitoring the sensing system offers. Thus, newly improved distributed sensors with 1 million sensing points provide prominently faster detection of structural problems that are now accessible.

Fiber optic sensors allow accurately detecting erosion or cracking before a dam fails. Therefore, earlier detection of a problem by fiber optic sensing systems may lead to its possible prevention from later deformation or provision of sufficient time for evacuation procedures. Fiber sensors are considered to be perfect for controlling infrastructure since they suit for use in harsh environmental conditions and in areas that lack nearby power supply.

The operating principle of distributed sensors is based on “changes in the structure at any of the sensing points along the optical fiber that cause detectable changes in the light traveling down the fiber”. Despite the high popularity of distributed fiber optic sensors, the main applications of sensors include the detection of leaks in oil pipes and structural health monitoring for landslides along railroads.

It should be noted that the novel fiber optic sensing system enables tracing train and temperature changes from 1 million sensing points over a 10-kilometer optical fiber in less than 20 minutes, while strain parameter demonstrates deformation or mechanical stress on an object of interest. Herewith, the new distributed sensor is regarded as to be about 4.5 times faster than previous fiber sensors with 1 million sensing points. A larger number of sensing points require fewer optical fiber units for structural health monitoring of an entire structure resulting in cost reduction.

A large density of sensing points makes distributed fiber optic sensors suitable for such applications as avionics and aerospace, where every inch of a plane wing has to be controlled properly. According to researchers, the conventional technique of generating the continuous signal in fiber sensors undertakes distortions in the fiber optic system at higher laser powers. This problem has been solved by using the approach known as Brillouin optical time-domain analysis.

The fiber optic sensor has been already tested and showed the opportunity to measure the temperature of a hot spot to within 3 degrees Celsius from the end of a 10-kilometer long optical fiber. Additionally, it is planned to improve the distributed sensor and make it even faster resulting in the further reduction of the acquisition time. Future enlargement of sensing point density will promote the fiber sensors being used in new fields, for example, biomedical applications.

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editorDistributed sensors for structural health monitoring of bridges and dams

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