scholarly journals Interrogation of fibre Bragg gratings through a fibre optic rotary joint on a geotechnical centrifuge

2016 ◽  
Author(s):  
Ricardo Correia ◽  
Stephen W. James ◽  
Alec Marshall ◽  
Charles Heron ◽  
Sergiy Korposh
Keyword(s):  
Bragg Gratings ◽  
Fibre Optic ◽  
Geotechnical Centrifuge ◽  
Rotary Joint ◽  
Fibre Bragg Gratings

Leak detection on water pipelines in unsaturated ground by discrete fibre optic sensing

2019 ◽  
Vol 19 (4) ◽  
pp. 1219-1236 ◽  
Author(s):  
Schalk Willem Jacobsz ◽  
Sebastian Ingo Jahnke
Keyword(s):  
Unsaturated Soil ◽  
Ground Deformation ◽  
Bragg Gratings ◽  
Leak Detection ◽  
Bragg Grating ◽  
Fibre Bragg Grating ◽  
Fibre Optic ◽  
Temperature Changes ◽  
Water Leak ◽  
Fibre Bragg Gratings

The article describes a study using discrete fibre optic sensing as a means of leak detection on water distribution pipes installed in unsaturated ground. A short length of pipe fitted with artificial leak points was installed, to which a fibre optic cable with fibre Bragg gratings was attached. An optical fibre with fibre Bragg gratings was also installed in the ground parallel to but separate from the pipe. Thermistors were installed at selected locations to measure temperature changes independent of strain. It was found that a simulated water leak resulted in clearly detectable temperature changes and thermally induced fibre Bragg grating wavelength changes in the ground around the pipe. However, significantly larger deformation-induced fibre Bragg grating wavelength changes were measured on the pipe walls and also in the initially unsaturated ground in response to leaks. A wetting front originating from a water leak propagating through unsaturated soil is associated with significant effective stress changes because the infiltrating water alters the ambient matric suction in the soil. This effective stress change is associated with significant ground deformation resulting in a fibre Bragg grating response which significantly exceeds the thermal response associated with (usually) colder water leaking into unsaturated soil. The study illustrates advantages of measuring ground deformation-induced fibre Bragg grating wavelength changes over pure temperature changes as an efficient means of leak detection in unsaturated ground. However, due to the limited number of fibre Bragg gratings that can be monitored along a single optical fibre, a leak detection system suitable for practical implementation should be based on distributed fibre optic strain sensing, an aspect requiring further research.

Temperature-Insensitive Fibre-Optic Acceleration Sensor Based on Intensity-Referenced Fibre Bragg Gratings

2008 ◽  
Vol 25 (10) ◽  
pp. 3593-3596 ◽  
Author(s):  
Sun Li-Qun ◽  
Dong Bo ◽  
Wang Yong-Xin ◽  
Evan LALLY ◽  
Wang An-Bo
Keyword(s):  
Bragg Gratings ◽  
Fibre Optic ◽  
Acceleration Sensor ◽  
Fibre Bragg Gratings

scholarly journals Dual Measurement of Strain and Temperature Using the Combination of Er3+ -Doped Fibre Fluorescence Lifetime and a Fibre Bragg Grating

2001 ◽  
Vol 34 (6) ◽  
pp. 175-178 ◽  
Author(s):  
S.A. Wade ◽  
D.I. Forsyth ◽  
Q. Guofu ◽  
X. Chen ◽  
T. S. Chuan ◽  
...  
Keyword(s):  
Fluorescence Lifetime ◽  
Bragg Gratings ◽  
Bragg Grating ◽  
Fibre Bragg Grating ◽  
Fibre Optic ◽  
Erbium Doped ◽  
Fibre Bragg Gratings ◽  
Dual Measurement

Fibre optic sensing devices have been produced for the dual measurement of strain and temperature using the combined properties of fibre Bragg gratings and the fluorescence lifetime of erbium-doped fibre. Two different sensors were constructed with the fibre Bragg grating written in normal fibre and also written directly in the Er3+-doped fibre. Results obtained indicate that this technique can be used to measure strains and temperatures with accuracies of approximately 1.2°C and 20.4 με

A new fibre optic sensor independent of temperature variations and fabricated with fibre Bragg gratings

2004 ◽  
Author(s):  
J. C. Roig ◽  
R. Garcia ◽  
S. Sales ◽  
Jose Capmany ◽  
Beatriz Ortega ◽  
...  
Keyword(s):  
Bragg Gratings ◽  
Fibre Optic ◽  
Temperature Variations ◽  
Fibre Optic Sensor ◽  
Optic Sensor ◽  
Fibre Bragg Gratings

Fibre Bragg Gratings in Harsh and Space Environments: Principles and applications

2019 ◽  
Author(s):  
Brahim Aissa ◽  
Emile I. Haddad ◽  
Roman V. Kruzelecky ◽  
Wes R. Jamroz
Keyword(s):  
Bragg Gratings ◽  
Space Environments ◽  
Fibre Bragg Gratings
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