Detecting Structural Faults Sooner With Fiber Optics
Among those who presented technical papers at OFC/NFOEC 2006 were University of Ottawa physicists who have demonstrated an optical system that detects problems in important structures, including natural-gas pipes and concrete columns, more precisely than before.
Called the distributed brillouin sensor (DBS), the system uses fiber optics to detect deformation, cracks and bending in structures under real-world conditions. Already being considered for commercial production, the new system can catch much earlier signs of costly and dangerous structural failures than previously possible.
In one demonstration, conducted with civil engineers at the University of Ottawa, the researchers tested the DBS system on a concrete column encased with fiber-reinforced rods and sheets. Subjecting the column to simulated seismic forces such as those that would occur in an earthquake or tsunami, the researchers could detect signs of debonding (in which the concrete detached from the fiber casing) and the crushing of concrete as a result of compression forces. Unlike competing techniques, the system could readily tell the difference between debonding and crushing.
The Ottawa researchers said DBS can prevent potentially life-threatening and environmentally damaging accidents and multimillion-dollar repairs. Unlike present structural health analysis, which is done on a spot-by-spot basis, DBS can detect problems over all points in the entire structure and pinpoint them to within 5 centimeters, while detecting mechanical strains as low as 20 microstrains, exceeding the 1-meter resolution and 50 microstrain levels that the construction industry has wanted and expected. In addition, the technique can improve the testing of structures and materials by providing valuable information during the testing process. (Paper OTuL7, "Distributed Brillouin Sensor Based on Brillouin Scattering for Structural Health Monitoring")
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