The Theoretical Analysis of Fiber Bragg Grating Sensors in Strain Gradient Measurement and The Applications in Shape Memory Alloy
Date Issued
2011
Date
2011
Author(s)
Chen, Ya-Fang
Abstract
Since optical fiber has several excellent properties of optical propagation, it has been noticed in the signal processing and communication field for a long time. With fiber grating’s development, fiber is also utilized to mechanical measurement, and Fiber Bragg grating (FBG) sensor is one of the most applications. The essay will discuss the advantage foe FBG sensor that other sensors are hard to achieve.
In mechanical measurement field, FBG sensor most applies on uniform strain field or specific point measurement by measuring FBG sensor’s reflect peak wavelength. This essay is using FBG sensor to measure the linear strain gradient by calculating the area of reflected spectrum, and the results are highly consistent with the simulation of coupled-mode theory. Through power meter, we can obtain the spectrums’ area size without post processing to measure the variance of strain gradient immediately.
Since FBG sensors are thin (in diameter) and flexible, we utilize it to measure the string structure with even smaller diameter than FBG sensor which is hard to be measured by other contact sensor. The result shows that FBG sensor not only can measure thin string structure but also has high sensitivity of small strain variance by power modulated sensing system. We extend FBG sensor’s application to measure shape-memory alloy (SMA) with collocation, since SMA’s self-sensing model is hard to build and the accuracy is easy to effect by environment
Subjects
FBG sensor
strain gradient
area of reflect spectrum
SMA
Type
thesis
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