Coaxial Cable Bragg Grating Sensors for Structural Health Monitoring

Abstract

In situ strain monitoring is critical to ensure the continued safe and reliable operation of various civil structures, such as dams, bridges, and buildings. In situ strain monitoring is especially important for structures that may experience large strains. In this project, 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 the Bragg grating theory. By monitoring the resonant frequency shift of the sensor's reflection or transmission spectra, strain measurement sensitivity of 20µε and a dynamic range of 50000 µε (5%) were demonstrated for axial strain measurements. The experimental results show that the CCBG sensors perform well for the large strain measurement needed in structural health monitoring (SHM).

Department(s)

Electrical and Computer Engineering

Sponsor(s)

National Science Foundation (U.S.)

Comments

This material is based upon work supported by the National Science Foundation under Grant No. 1100185.

Keywords and Phrases

Bragg grating sensors; Civil structure; Computer numerical controlled; Discrete frequencies; Drill hole; Dynamic range; Grating theory; In-situ; Large strains; Measurement sensitivity; Reliable operation; Resonant frequency shift; Sensor device; Strain sensors; Transmission spectrums, Bragg gratings; Cables; Coaxial cables; Electromagnetic wave propagation; Natural frequencies; Strain; Strain measurement; Structural health monitoring; Sensors; Coaxial cable bragg grating; Large strain sensor

International Standard Serial Number (ISSN)

1996-6814; 1997-1400

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2012 Chinese Society of Pavement Engineering, All rights reserved.

Publication Date

01 Sep 2012

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