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Optical Structural Health Monitoring DeviceThis non-destructive, optical fatigue detection and monitoring system relies on a small and unobtrusive light-scattering sensor that is installed on a component at the beginning of its life in order to periodically scan the component in situ. The method involves using a laser beam to scan the surface of the monitored component. The device scans a laser spot over a metal surface to which it is attached. As the laser beam scans the surface, disruptions in the surface cause increases in scattered light intensity. As the disruptions in the surface grow, they will cause the light to scatter more. Over time, the scattering intensities over the scanned line can be compared to detect changes in the metal surface to find cracks, crack precursors, or corrosion. This periodic monitoring of the surface can be used to indicate the degree of fatigue damage on a component and allow one to predict the remaining life and/or incipient mechanical failure of the monitored component. This wireless, compact device can operate for long periods under its own battery power and could one day use harvested power. The prototype device uses the popular open-source TinyOS operating system on an off-the-shelf Mica2 sensor mote, which allows wireless command and control through dynamically reconfigurable multi-node sensor networks. The small size and long life of this device could make it possible for the nodes to be installed and left in place over the course of years, and with wireless communication, data can be extracted from the nodes by operators without physical access to the devices. While a prototype has been demonstrated at the time of this reporting, further work is required in the system s development to take this technology into the field, especially to improve its power management and ruggedness. It should be possible to reduce the size and sensitivity as well. Establishment of better prognostic methods based on these data is also needed. The increase of surface roughness with fatigue is closely connected to the microstructure of the metal, and ongoing research is seeking to connect this observed evidence of the fatigue state with microstructural theories of fatigue evolution to allow more accurate prognosis of remaining component life. Plans are also being discussed for flight testing, perhaps on NASA s SOFIA platform.
Document ID
20100024428
Acquisition Source
Armstrong Flight Research Center
Document Type
Other - NASA Tech Brief
Authors
Buckner, Benjamin D.
(MetroLaser Irvine, CA, United States)
Markov, Vladimir
(MetroLaser Irvine, CA, United States)
Earthman, James C.
(California Univ. CA, United States)
Date Acquired
August 24, 2013
Publication Date
July 1, 2010
Publication Information
Publication: NASA Tech Briefs, July 2010
Subject Category
Man/System Technology And Life Support
Report/Patent Number
DRC-007-065
Report Number: DRC-007-065
Distribution Limits
Public
Copyright
Public Use Permitted.
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