Application of the Fiber Bragg Grating on Pressure Sensor Design and Manufacturing and Measurement of Transient Strains
Date Issued
2015
Date
2015
Author(s)
Ko, Ping-Liang
Abstract
Recently, the optical fiber sensors, especially the fiber Bragg grating (FBG) sensors, have been rapidly developed due to the advantages such as excellent mechanical properties, thin geometries, high sensitivity and electromagnetics immunity. It can be applied to static analysis by demodulating the FBG central wavelength or dynamic measurement by power modulated system, and both of them can measure multiple points in the same time with wavelength division multiplexer. On the other hand, digital image correlation (DIC), which is a non-contact and full field measurement technique, has also been used widely for measurement of displacement and strain problems. Both of them are developed in our laboratory and this thesis is going to use these techniques to design the high precision pressure sensors and improve these developed measurement techniques. The main object of this research is focused on the application of FBG on measuring small pressure changes due to the disturbance of fluid. We also use the theory of thin plate and the coupled mode theory to design FBG pressure sensors. The FBG pressure sensor we designed and manufactured can be used for measuring not only the air pressure but also the water pressure. It can detect the small pressure change by the I-MON system or the dynamic pressure change from power modulated system. Then we compared the signals, which include the water pressure, the pressure change of the loudspeaker system and the fan system, with the commercially available pressure sensors. We also compared the sensitivity and response of the FBG pressure sensor with theoretical simulation. In terms of the FBG measurement techniques, we did a series experiments and compared to other measurement system to confirm the accuracy of the signals acquired by the I-MON system. We also introduced a wide bandwidth tilted fiber Bragg grating as the filter in power modulated system to measure the high amplitude and dynamic signals. Furthermore, we evaluate the feasibility of the application of FBG on the turning tools monitoring by comparing the experiment results with the dynamometer.
Subjects
Fiber Bragg Grating
Digital Image Correlation
strain
power modulated method
pressure sensors
coupled mode theory
transient wave propagation
Type
thesis
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