Masters Theses

Abstract

"In order to ensure the continued safe and reliable operation of various civil structures, such as dams, bridges, and buildings, in situ strain monitoring is of great importance, especially for structures that may experience large strains. A new coaxial cable Bragg grating (CCBG) is developed as a strain sensor and the sensor's capacity for large range strain measurement is demonstrated for the first time. The sensor device is comprised of regularly spaced periodic discontinuities along a coaxial cable. The discontinuities are fabricated using a computer numerical controlled (CNC) machine to drill holes in the cable. Each discontinuity generates a weak reflection to the electromagnetic wave propagating inside the cable. Superposition of these weak reflections produces a strong reflection at discrete frequencies that can be explained by Bragg grating theory. A positive feedback oscillation system is also developed to enhance the measurement accuracy. The Q-factor was enhanced by 3500 times in this case. By monitoring the resonant frequency shift of the sensor's reflection or transmission spectra using the oscillation system, strain measurement sensitivity of 20με and a dynamic range of 50000με (5%) were demonstrated for axial strain measurements. The temperature responses of various types of CCBGs have also been investigated. The experimental results show that the CCBG sensors perform well for large strain measurement needed in structural health monitoring (SHM)"--Abstract, page iii.

Advisor(s)

Xiao, Hai, Dr.

Committee Member(s)

Fan, Jun, 1971-
Tsai, Hai-Lung

Department(s)

Electrical and Computer Engineering

Degree Name

M.S. in Electrical Engineering

Sponsor(s)

National Science Foundation (U.S.)

Publisher

Missouri University of Science and Technology

Publication Date

2012

Pagination

viii, 37 pages

Note about bibliography

Includes bibliographical references (pages 33-36).

Rights

© 2012 Jie Huang, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Subject Headings

Coaxial cables -- Testing
Bragg gratings
Electromagnetic compatibility
Electronic circuits -- Noise

Thesis Number

T 10554

Print OCLC #

903643283

Electronic OCLC #

903650630

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