The Transient Strain Measurement on Wedges of Three Dimensional Solids Using the Fiber Bragg Grating Sensor
Date Issued
2012
Date
2012
Author(s)
Wang, Chun-Yao
Abstract
Recently, Fiber Bragg Grating has become a popular sensor to all walks of life for its excellent transmission characteristics and mechanical properties. And its static and dynamic, especially with power modulation, measurement ability has been recognized as well. Different from other sensors such as strain gauge and piezoelectric file, optical fiber has slender geometric characteristic that can apply to some tricky positions, which other sensors failed to achieve.
The thesis is to discuss the result by using FBG’s slender geometric characteristic to measure the dynamic strain behavior on edge and vertex of a three-dimensional solid. The experiments will be divided into two parts, the measurement of one-dimensional transient strain on solid edge and the measurement of three-dimensional transient strain on solid vertex. First, by using free fall steel ball to impact the structure, a long time response will be generated. Transferring the long time response to get the resonant frequency by using Fast Fourier Transform, then compare with the simulate result by using finite element method. After confirming the resonant frequency is correct, I use PVDF sensor to measure the force history of the impact of free fall steel ball. With the force history, we can simulate the transient wave propagation result by using finite element method and compare with the measurement result by using Fiber Bragg Grating sensor. After getting the dynamic characteristic of solid in the air, the next step is to analysis the problem of the solid-liquid coupling. Put the solid into the water and measure the change of time response and resonant frequency under different water levels.
Subjects
Fiber Bragg Grating, PVDF film sensor, power modulated sensing system, force history, finite element method, three-dimensional structure dynamic strain sensing, transient wave propagation, solid-liquid coupling
Type
thesis
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