Fiber optic sensors have been utilized as corrosion sensors by depositing metal coatings to the surface of the sensors. Three types of fiber optic sensors were investigated as candidates for corrosion detection: the extrinsic Fabry-Perot interferometer (EFPI), the absolute extrinsic Fabry-Perot interferometer (AEFPI), and the long period grating (LPG) fiber optic sensor. The corrosion monitoring technique used with the EFPI and AEFPI sensors exploits the ability of a thick coating of metal to maintain strain information in fiber optic strain sensors. The sensors are placed under tensile stress, and while in the resulting strained position, a thick coating of metal is applied. Due to an increase in the quantity of material, the sensor does not return to its original position upon release, and strain is maintained within the sensor element. As the metal thickness decreases due to corrosion, this residual strain is released, providing the sensing mechanism for corrosion detection. LPG fiber optic sensors have demonstrated their ability as bandstop filters, by coupling the fundamental guided mode to circularly symmetric cladding modes. The cladding modes are extremely lossy due to the fiber jacket and bending along the fiber. Losses at discrete wavelengths can be monitored to determine the onset and progress of metal corrosion. Background theory and experimental results are discussed and reported for EFPI, AEFPI, and LPG fiber optic corrosion sensors. The study is preceded with an overview of different corrosion sensor designs and methods which are used in the area of non-destructive evaluation. / Master of Science
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/74546 |
| Date | January 1995 |
| Creators | Schindler, Paul M. |
| Contributors | Electrical Engineering |
| Publisher | Virginia Polytechnic Institute and State University |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | ix, 71 leaves, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 34408904 |
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