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Structural Health Monitoring Using Distributed Fiber Optic Sensors.
Recent advancements in Fiber optic sensing technology make it possible to acquire the strain profile in a structure in a distributed manner. Rayleigh Based Fiber Optic sensing provides higher spatial resolution in a normal communication fiber. Low cost of the fiber and large number of sensing points in a single fiber make it a promising choice for detecting local variations in strain produced by structural damages in composites such as disbonds and delaminations. At present, the sampling rate and instrumentation are suitable only for ground-based applications. However, it is expected that with advances in fiber optic and photonic technologies like OFDR and draw tower FBG techniques, flightworthy distributed sensing instrumentation will become a reality soon.
Specifications:
Distributed Fiber Optic system based on Rayleigh scattering ODiSiB form LUNA (100 Hz, 5mm spatial resolution 10 m sensing length)
Major milestones / results of this technique
Extensive composite test box level studies were carried out and detection of disbond (location and Size of the disbond) was demonstrated, where disbonds were simulated by removing the fasteners between spar and skin. Algorithms were developed to detect disbonds from strain profile acquired from a composite box structure.
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Strains Response from Healthy structure |
Strains Response from structure with Disbond |
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Top view of Test Box |
Two disbonds detected using algorithm |
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Software implementation |
Results for disbond estimation (dotted line indicate the actual disbond and the dots indicate the location estimated at different loads) |
