| Bridges:
Short--term health monitoring of a MSS formwork
Case study of optical monitoring system on the Gi-Heung 1 bridge in Korea. (read
entire article) Copyright
2008; posted with permission. Health
Monitoring of Rehabilitated Concrete Bridges Using Distributed Optical Fiber Sensing
by Wei Zhang, Junqi Gao, Bin Shi, Heliang Cui, Hong Zhu (2006) Click
here to read full article in Computer-Aided Civil and Infrastructure Engineering
FBG Bending Gauge on bridges –
An effort towards standardization of bridge structural health monitoring
By I-Wen Wu, Chung-Yue Wang, Ming-Hung Chen, Hao-Lin Wang, Allen Cheng, Patrick
Tsai, David Wu, Hung-Wei ChangChien, Hentai Shang "The
FBG bending gauge developed by POFC is applied in several situations involving
bridge safety/health monitoring. Under static loading conditions, the FBG bending
gauge serves as an excellent tool to deduce an overall deflection curve on the
bridge section under study. The gauge also works well in dynamic situations where
instantaneous vertical deflections of bridge structures resulting from a cruising
dump truck were accurately measured.."(read
entire article) Copyright
2006; posted with permission of POFC. Troubleshoot
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to top The Application of FBG Sensing
in Monitoring Hulanhe Bridge in Heilong Jiang Province
By Dr. Zhi Zhou,
et.al., School of Civil Engineering "Fiber
Bragg Gratings (FBG) sensors have been deployed in many engineering applications
in the international arena, ranging from bridges, aerospace vehicles, composite
materials, concrete, high-voltage transmission lines, to bio-chemistry. Although
domestic research and development in FBG sensors have made significant progress,
there is yet a comprehensive report on their engineering applications. In a province-wide
effort to motivate the use of FBG sensors in bridge engineering, the Heilong Jiang
Department of Transportation, with the support of Heilong Jiang Road and Bridge
Company, established a FBG application program in the Harbin Institute of Technology
(HIT) with the specific objective to develop bridge monitoring testbeds..."(read
more) Copyright 2005 Harbin
Institute of Technology. Used with permission of the authors. Troubleshoot
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to top The Application of FBG Sensing
in Monitoring Ebian Daduhe River Bridge in Sichuan Province
By Dr. Zhi
Zhou, et.al., School of Civil Engineering "The
Ebian Daduhe bridge in Sichuan province...was constructed in 1995, spanning 138m.
Due to pollution from an up-stream sulfur processing plant, the bridge suffered
serious corrosion. From October 2004 to October 2005, the bridge under went extensive
maintenance construction and repair. The design on the new suspension cables requires
continual health monitoring.."(read
more) Copyright 2005 Harbin
Institute of Technology. Used with permission of the authors. Troubleshoot
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to top The Maturing of Optical Sensing
Technology for Bridges, Dams, Tunnels, Reservoirs and other Commercial Applications
By A. Csipkes, S. Ferguson, T.W. Graver, T. C. Haber, A. Méndez, J. W. Miller "In
this paper, we present a brief overview on the latest advances on optical fiber
sensors and instrumentation for structural health monitoring (SHM) applications.
Successful, field-proven, installations and reliability studies that validate
the technology are also discussed. Emphasis is placed in reviewing actual commercially
available solutions and equipment.."(read
more) Copyright 2005 Micron
Optics, Inc. Troubleshoot
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to top Applications of FRP-OFBG Sensors
on Bridge Cables
By Zhi Zhou, Nianchun Deng, Zhichun Zhang, Xuefeng Zhao,
Dongsheng Li, Jinping Ou "It is still a practical
problem how to effectively install FBG sensors on bridge cables. In this paper,
a simple and effective solution is introduced to develop smart bridge cables using
FRP-OFBG bars developed in HIT (Harbin Institute of Technology). Here, the FRP-OFBG
bar acts as one component of the cable and shows force resistance and well-protected
sensors in service. The installation techniques and the sensing properties of
FBGs in three kinds of cables, FRP cables, common steel-wire cable and extruded-anchor
cable, are introduced and tested under dead load..."(read
more) Copyright 2005;
used with permission of the authors. This paper was presented at Smart Structures
& Materials/NDE Joint Conference in San Diego, USA, 2005 Troubleshoot
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to top Characterizing Aged
Bridge Response by Loading Test
Copyright 2005
POFC. This application note posted with permission of POFC Long
Term Structural Health Monitoring of the Hampden
Suspension Bridge
Copyright 2005 MOS. This application
note posted with permission of Monitor Optics Systems in Australia. Troubleshoot
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to top Remote Health Monitoring of a High Performance
Steel Bridge Using Fiber Optic Technology
by J.D. Doornink, B.M. Phares,
A. Abu-Hawash, T.J. Wipf, D.J. Hemphill, L.F. Greimann "In
early 2004, the Iowa Department of transportation (DOT) completed construction
of Iowa's first High Performance Steel (HPS) bridge ...the Bridge Engineering
Center at Iowa State University has developed a continuous Structural Health-Monitoring
(SHM) system to monitor and record the performance of the HPS bridge for a two-year
period. With this system, the bridge performance can be evaluated at any point
in time...(read entire article) Copyright
2004 BEC; posted with permission of the Bridge Engineering Center of the Iowa
State University Research Park. For more information regarding the Bridge Engineering
Center, go to their website /www.bec.iastate.edu/. Troubleshoot
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to top Structural Health Monitoring
of a Steel Railway Bridge using Optical Fibre Bragg Grating Sensors and Numerical
Simulation
By George J. Tsamasphyros, Elias A. Koulalis, George N. Kanderakis,
Nikos K. Furnarakis, Vangelis Z. Astreinidis "The
application of structural health monitoring techniques to a late 19th century
steel railway bridge located at Nea Peramos near Athens Greece, still under regular
usage, has been attempted using optical fiber Bragg grating sensors. As a first
step, one fiber Bragg grating sensor was placed in the middle of a secondary beam
section, exactly below the rail track on the one edge of the bridge and measurements
have been retrieved for trains..."(read
entire article) Copyright
2005; posted with permission of the authors. The
Application of FBG Sensors in Monitoring the Binzhou
Yellow River Bridge of Shandong Province
Copyright
2006 Harbin Institute of Technology (HIT). This application note posted with permission
of HIT Troubleshoot
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to top 
Civil
Structures & Engineering: Underwater
application of structural health monitoring at Fairview Cove Container Terminal
by V. Limaye; J. Gaudet; J. Newhook; D. Carter For
the full article, go to SPIE.org Standards
and guidelines - could they enhance user confidence in fibre sensor technology?
by Wolfgang R. Habel Different experience
from fibre sensor applications on-site has revealed the need of guidelines for
developers, manufacturers, suppliers as well as users. Although best knowledge
and well-founded experience are available in the fibre sensor community, a lack
of technical instructions for all persons involved can lead to unreliable measurement
results or even damage of sensing components. In contrast, manufacturing and application
procedures according to generally binding technical rules will ensure long-term
stable sensor systems and reliable measurement results. These rules have to include
definitions of particular terms to describe the sensor and sensor system characteristics
as well as methods to validate and use sensors properly.
(Read entire article) Copyright
2007; posted with permission of the author. This paper was presented at EWOFS
2007 in Naples , Italy. Troubleshoot
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to top An Industrial Perspective on
the Applications of Optical Sensing Technology in Selected Fields
by Allen
Cheng, David Wu, Vincent Chang Chien, Patrick Tsai, and I-Wen Wu A
brief take on the optical sensing technology is provided in this paper with a
main focus on the FBG technology. This work discusses the components that are
required to assemble a proper FBG optical sensing system, namely the sensors,
interrogators, signal transmission lines/cables, custom software, and most importantly,
the installation work. A few key examples of work done by POFC and collaborators
will be presented and discussed.(Read
entire article) Copyright
2006 POFC; posted with permission of Prime Optical Fiber Corporation. For more
information regarding POFC, go to their website at www.pofc.com. A
novel ice-pressure sensor based on dual FBGs
By Zhi Zhou, Chunguang Lan,
Taiming Lin, Jinping Ou Ice pressure is
one of the most important loads in high-latitude area. It is challengeable to
build a durable and stable real-time structural health monitoring system for ice-pressure
under such aggressive environment as windiness, coldness, and even vibrating,
which can not be met by strain gauge based sensors, whereas FBG fits it well due
to its great advantage of corrosion resistance, absolute measurement, high accuracy,
electro-magnetic resistance, quasi-distribution sensing, absolute measurement
and so on. In this paper, a novel FBG based ice-pressure sensor has been developed.
(Read entire article)
Copyright 2005; used with permission of the authors. This paper
was delivered at Smart Structures & Materials/NDE Joint Conference: Sensors
and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems,
SPIE, San Diego, USA, 2005 Troubleshoot
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to top Development of FBG Sensors
for Structural Health Monitoring in Civil Infrastructures
Zhi Zhou and
Jinping OU In recent years, FBG (Fiber Bragg
Grating) has been accepted as a new kind of sensing element for structural health
monitoring (SHM) in civil infrastructures. Cost of FBG fabrication, high-quality
FBG demodulation system, practical encapsulation (package) techniques and indirect
FBG-based sensors, and practical applications are the cores for FBG to be widely
popularized in infrastructures. In this paper, firstly, the FBG fabrication and
demodulation system are briefly introduced and the practical needs from infrastructure
are pointed out; Secondly, the practical encapsulation (package) techniques and
indirect FBG based sensors from Harbin Institute of Technology (HIT), have been
conducted; Thirdly, some practical applications, taken as examples, are carried
out; Finally, the future studies and problems are also set forth. Researches and
practical applications show that FBG sensors have become one of the key sensors
in SHM instead of some conventional electrical sensors.
(Read
more) Copyright 2004;
used with permission of the authors. This paper was delivered at Proceeding of
North American Euro-Pacific Workshop "Sensing Issues in Civil Structural
Health Monitoring" , 2004, Waikiki Beach, Oahu ,Hawaii ,USA Troubleshoot
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to top Fiber Bragg Grating Sensing
for Structural Health Monitoring of Civil Structures
By J. D. Doornink,
T.W. Graver, JP Ou, B. M. Phares and Z. Zhou
Structural Health Monitoring (SHM) is fast becoming a highlight of both research
and applications in civil engineering. One key driver is the ever-improving function
and cost of fiber-optic sensing (FOS) systems. To date, FOS has been used on hundreds
of civil structures around the world. This paper focuses on two initiatives that
rely on FOS. Researchers from Iowa State University's Bridge Engineering Center
demonstrate a novel approach to SHM data management, analysis and presentation.
Preliminary results are shown and links to live data are provided. At the Harbin
Institute of Technology, civil engineers are studying local damage on large-span
bridges. Current work focuses on solving key practical challenges for several
existing and new large spans.
(Read
entire article) Copyright
2004. This paper was delivered at the International Symposium on Advances and
Trends in Fiber Optics and Applications October 11-14, 2004. Troubleshoot
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to top Growing Market Acceptance for
Fiber-Optic Solutions in Civil Structures
By T.W. Graver, D. Inaudi, J.
Doornink Owners must manage and ensure the
safety of their civil structures even as use of many structures extends well beyond
their design lifetime. Traditionally, most structures rely on strict maintenance
procedures, visual inspections, and very few sensors. But maintenance is very
expensive, visual inspections can miss critical problems, and conventional sensors
can fail in harsh environments. Can fiber-optic sensing (FOS) address these issues?
This is not a new question, but there are some new answers. This paper highlights
several structures where FOS is used, and describes the associated successes and
challenges for each application. Many successes are coupled to improved FOS tools:
better sensor packages, simpler and less expensive instrumentation, improved installation
techniques, and more efficient data analysis tools. Examples of each are provided.
Particular attention is given to the economics of instrumenting civil structures
- when and how it pays. Conclusions include recommendations for future developments
that will further accelerate FOS acceptance and use. (Read
entire article) Copyright
2004 Micron Optics. This paper was delivered on October 27, 2004 at Optics East
in Philadelphia, PA, USA. Recent
Progress on Structural Health Monitoring by Fibre Optic Sensor In Civil Engineering
By Hong-Nan LI, Liang Ren view
presentation Copyright
2005. This paper was delivered at the 3rd China-Japan-US Symposium on Structural
Health Monitoring and Control (Dalian, China, October 13-16, 2004) Posted with
permission of the author. Troubleshoot
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Concrete
Beams: Smart FRP-OFBG Bars and their Application
in Reinforced Concrete Beams
by Z. Zhou, J.P. Ou & B. Wang "Fiber
Reinforced Polymer (FRP) has become more and more popular as construction material
in civil engineering due to its advantages of corrosion-resistance, high strength,
nonmagnetic, fatigue-resistance... Optical Fiber Bragg Grating (OFBG) is now widely
accepted as [a] smart sensor due to its advantages of electric-magnetic resistance,
small size, distributing measurement, durability, and so on. Combined the strength
properties of FRP with the sensing properties of OFBG, a new kind of smart FRP-OFBG
composite bars has been developed.... The
experiment of FRP-OFBG reinforced
concrete beams under static load has been done, and ....(read
entire article) Copyright
2004 HIT; posted with permission of the Harbin Institute of Technology in China. Troubleshoot
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Energy:
Fundamentals for Remote Structural Health
Monitoring of Wind Turbine Blades - a PreprojectAnnex A - Cost-Benefit for
Embedded Sensors in Large Wind Turbine Blades
by Lars Gottlieb Hansen and
Lars Lading For the full article, go to the
Risø National Laboratory's website
Intelligent Monitoring System With High Temperature
Distributed Fiberoptic
Sensor For Power Plant Combustion Processes
by
Kwang Y. Lee, Stuart S. Yin, and Andre Boehman For
the full article, to to OSTI
website Troubleshoot
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to top Temperature monitoring of nuclear
reactor cores with multiplexed fiber Bragg grating sensors
by Alberto F.
Fernandez; Andrei I. Gusarov; Benoit Brichard; S. Bodart; K. Lammens; Francis
Berghmans; Marc C. Decreton; Patrice Megret; Michel Blondel; Alain Delchambre To
purchase this article, go the SPIE
Digital Library Back to top
Geotechnical: Applications
of Optical Fiber Sensor on Local Scour Monitoring
By Yung Bin Lin, Kuo
Chun Chang, Jihn-Sung Lai, I-Wen Wu "Scour
is one of the major causes for bridge failure. A real-time optical fiber sensory
system for bridge scour, using fiber Bragg grating (FBG) sensors, has been developed
and tested. These optical fiber sensors, especially the FBG scour-monitoring system,
can measure both the process of scouring and the variation of water level change.
Several test runs have been conducted in the laboratory and in-site bridge to
demonstrate the applicability of the FBG system. The results have shown that the
system has the potential to be applied in the field to a real-time monitoring
application for bridge scouring.."(Read
entire article) Copyright
2006; posted with permission of POFC. Troubleshoot
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to top Establishment [of] the Bridge
Scour Safety Monitoring System by Using Fiber Bragg Grating Sensors Introduction
By Yung Bin Lin, Kuo Chun Chang "... Scouring
at a bridge pier in the river can be caused by general scour, contraction scour
or local scour. Among them, local scour is the most critical and generally caused
by the interference of the structures with river flow. In the present study, it
is shown that the FBG sensors have demonstrated the capability to measure the
water level, scour depth and deposition height at the Dadu Bridge. The field results
indicate that the real-time monitoring system using FBG sensors have the potential
for real world applications."(Read
entire article) Copyright
2006; posted with permission of POFC. Troubleshoot
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to top Long-term Monitoring
of Seismic Changes of a Key Fault
Copyright 2005
POFC; posted with permission of Prime Optical Fiber Corporation. Real
Time Subsea Monitoring and Control Smart Field Solutions
by D. Brower
and N. Prescott A new method to monitor and
control subsea pipelines and facilities is in development. The new method involves
the integration of the latest technology advancements in the industry coupled
with standard state-of-the-art pipeline technology. The result is a pipeline and
facilities system that is auto adaptive to the environment so that real-time problem
identification and corrective action can be implemented. Potential pipeline problems
will be mitigated to avoid costly down time and repair. The technology will significantly
reduce environmental contamination concerns. It is expected that years of trouble
free pipeline usage will be possible with an enhanced overall service life expectancy.(Read
entire article) Copyright
2004; posted with permission of Astro Technology Inc. Troubleshoot
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to top Real-time Flow Assurance Monitoring
with Non-intrusive Fiber Optics Technology
by D. Brower, N. Prescott,
J. Zhang, C. Howerter, D. Rafferty Flow assurance
is a key aspect of offshore, particularly deepwater developments. Tremendous progress
during the past two decades in the understanding of the issues and the required
technology has enabled the developments be designed and operated with low risk
of flow assurance problems. However, the problems have not been eliminated due
to system component failures or un-designed for operating conditions. Real time
monitoring of the production and transportation system can help significantly
reduce the occurrence and impact. The present paper discusses the use of non-intrusive
fiber optic technology for this purpose. (Read
entire article) Copyright
2005; posted with permission of Astro Technology Inc. Troubleshoot
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to top
Sensors:
Strain
Sensors Based on Bragg Gratings
By K. Haase Copyright
2007 HBM; posted with permission o fHBM, Inc. This paper was delivered
at the IMEKO 20th TC3, 3rd TC16 and 1st TC22 International Conference Cultivating
metrological knowledge 27th to 30th November 2007. Merida, Mexico Strain
Measurement with Fiber Bragg Grating Sensors
by Mandred Kreuzer Fiber
Bragg Grating Sensors (FBGS) are gaining increasing attention in the field of
experimental stress analysis. They are very well suited to the new materials of
glass and carbon fiber reinforced composites which are often used for highly stressed
constructions, e.g. in airplanes and wind power plants. This paper gives a short
introduction to FBG sensors, points out their special strengths and weaknesses
and describes a measuring system which enables strain gages and FBGS to be measured
simultaneously, providing all data processing functions originally developed for
the strain gages also for the FBGS signals, like signal conditioning, rosette
calculations, filtering, Fourier transformation, free definable mathematics etc.
(read entire article) Copyright
2007 HBM; posted with permission o fHBM, Inc. Troubleshoot
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to top
Volatile
organic compound sensing using a surface relief D-Fiber Bragg grating and a polydimethylsiloxane
layer
by Tyson Lowder, John Gordon, Stephen Schultz, and Richard Selfridge For
the full Article, please go to www.osa.org FlexPatch:
A Rugged Miniature FBG Strain Sensor
by Steve Ferguson, Don Snyder, Tom
Graver, Alexis Méndez "The design and
development of a novel opto-mechanical strain sensor—called FlexPatch (patent
pending)—based on the use of an optical fiber Bragg grating (FBG) mounted
into a custom-made miniature metallic flexure is reported. The FBG sensing element
is attached to a carrier flexure using proprietary bonding process which ensures
a linear, drift-free and repeatable strain response even under severe moisture
and temperature conditions. The sensor is uncompensated for temperature effects,
but has undergone extensive mechanical and environmental testing and is qualified
for use in a strain range of +/- 2,500 microstrain with a gage factor of 1.2pm/microstrain
over a temperature range from -40° to 120°C, and a fatigue life >100x106
cycles. The FlexPatch is intended for use in diverse sensing and monitoring applications
and can be installed onto surfaces by epoxy bonding or spot welding." (Read
entire article) Copyright
2007 Micron Optics, Inc. This paper was presented at SPIE NDE/Smart Structures
2007 in San Diego, CA USA. Troubleshoot
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to top Fiber Bragg grating multi-chemical sensor
by Patrick Boland, Gopakumar Sethuraman, Alexis Mendez, Tom Graver, Dmitry Pestov,
and Gregory Tait "Fiber optic-based chemical
sensors are created by coating fiber Bragg gratings (FBG) with the glassy polymer
cellulose acetate (CA). CA is a polymeric matrix capable of localizing or concentrating
chemical constituents within its structure. Some typical properties of CA include
good rigidity (high modulus) and high transparency. With CA acting as a sensor
element, immersion of the gratings in various chemical solutions causes the polymer
to expand and mechanically strain the glass fiber. This elongation of the fiber
sections containing the grating causes a corresponding change in the periodicity
of the grating that subsequently results in a change in the Bragg-reflected wavelengths.
A high-resolution tunable fiber ring laser interrogator is used to obtain room-temperature
reflectance spectrograms from two fiber gratings at two different wavelengths
– 1540nm and 1550nm..." .(read
entire article) Copyright
2007; posted with permission of the authors Troubleshoot
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to top Fiber
Sensors Lay Groundwork for Structural Heath Monitoring
Copyright
2006 Laser Focus World,
February 2006 issue Combined
Static and Dynamic Monitoring of Civil Structures with Long-gauge Fiber Optic
Sensors
By D. Inaudi, J.W. Miller, and T.W. Graver
Abstract: Long-gauge SOFO® sensors have been in use for the last 10 years
for the monitoring of civil, geotechnical, oil & gas and other structures. More
than 3500 sensors have been installed worldwide in a number of different structure
types. The original demodulation system is based on low-coherence interferometry
and is particularly suitable for the monitoring of long-term static deformations.
This paper reports the development and testing of a new sensing system based on
Fiber Bragg Gratings and allowing the monitoring of both the static as the dynamic
response of structures. The sensors are based on the well-proven SOFO packaging
and allow the measurement of deformations over measurement basis of 2m, with a
resolution of 1 microstrain and a frequency of 250 Hz. The system is insensitive
to temperature variations, electromagnetic disturbances (electric power lines,
lightning) and has demonstrated excellent long-term stability and durability.
Each sensor also contains a temperature gauge, useful for the evaluation of the
ambient parameters. (Read entire
article) Copyright
2005 Smartec; used with permission. This paper was delivered at the IMAC XXIII
Conference & Exposition on Structural Dynamics, January 31 - February 3, 2005.
Troubleshoot
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to top Experimental Investigation of
Optical Waveguide-Based Multigas Sensing
By Wei Peng, Gary Pickrell, Fabin
Shen, and Anbo Wang Abstract: In
this letter, the results of an experimental investigation for simultaneous multiple
gas detection utilizing an optical fiber sensor are described. The optical fiber
system used for these experiments contained a section of hollow tubing and this
allowed a combination of gas molecular absorption with optical waveguide technology.
A fiber-optic sensing structure was designed and demonstrated which can monitor
multiple gases simultaneously. The experimental results demonstrate the characteristic
absorptions in the optical spectra corresponding to the narrow molecular absorption
lines of the gases tested, which included acetylene and carbon monoxide. For
the full paper, visit
http://ieeexploer.ieee.org ©
2005 IEEE. Reprinted, with permission, from IEEE Photon. Technol. Lett., vol.
16, no. 10, pp. 2317-2319, 2004 Troubleshoot
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to top In-Situ Failure Identification
in Woven Composites throughout Impact using Fiber Bragg Grating Sensors
By James Pearson, Mohanraj Prabhugoud, Mohammed Zikry, Kara Peters
Abstract: In this study, measurements from low-impact velocity experiments
and surface mounted optical fiber Bragg grating (FBG) sensors were used to obtain
detailed information pertaining to damage progression in two-dimensional laminate
woven composites. The woven composites were subjected to multiple strikes at 2m/s
until perforation occurred, and the impactor position and acceleration were monitored
throughout each event. From these measurements, we obtained dissipated energies
and contact forces. The FBG sensors were surface mounted at different critical
locations near penetration-induced damaged regions. These FBG sensors were used
to obtain initial residual strains and axial and transverse strains that correspond
to matrix cracking and delamination (read
entire paper). © 2006
North Carolina State University, Department of Mechanical and Aerospace Engineering,
Reprinted, with permission, from the authors. Troubleshoot
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to top Miniature Fiber-Optic Pressure
Sensor
By Yizheng Zhu, and Anbo Wang
Abstract: This letter presents a miniature fiber-optic pressure sensor fabricated
directly on the tip of a fiber. The sensor measures only 125 /spl mu/m in diameter.
A Fabry-Pe/spl acute/rot cavity and a thin silica diaphragm are fabricated by
simple techniques involving only fusion splicing, cleaving, and wet chemical etching.
Interference pattern of the sensor is analyzed and issues in sensor design are
discussed. The sensor has been tested for static pressure response, showing excellent
repeatability and no hysteresis. Its all-fused-silica structure lends it great
potential for high-temperature pressure measurements. Pressure testing results
at 530/spl deg/C are given. The sensor may also find uses in medical applications.
For the full paper, visit
http://ieeexploer.ieee.org ©
2005 IEEE. Reprinted, with permission, from IEEE Photon. Technol. Lett., vol.
17, no. 2, pp. 447-449, 2005 Troubleshoot
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to top Process for Mounting and Packaging
of Fiber Bragg Grating Strain Sensors for use in Harsh Environment Applications
By V.P. Wnuk, A. Mendez, S. Ferguson, and T.W. Graver
Abstract: Over the last few years, optical fiber sensors have seen an increased
acceptance as well as a widespread use for structural sensing and monitoring in
civil engineering, aerospace, marine, oil & gas, composites and smart structure
applications... However, one of the areas in need of further development and commercial
maturity is that of sensor packaging and installation technique... In
this paper, we report the development of a new bonding agent and method for the
surface mounting of optical fiber Bragg grating strain and temperature sensors
for use in harsh environments--where there is a presence of water, moisture, dust,
susceptibility to corrosion and/or elevated temperatures up to 500 °C. The compound
is based on a combination of ceramic fillers with an epoxy binder that is applied
with a brush technique. The mounting procedure will be discussed along with experimental
results on the sensor's strain and temperature response under controlled environmental
conditions. (Read entire
article) Note: this
paper was delivered at the 2005 Smart Structures/NDE conference in San Diego,
California, March 8-9, 2005. Troubleshoot
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to top Radiation and Cladding Modes
as Independent Measurements of Bragg Grating Sensor Integrity
By Mohanraj
Prabhugoud, James Pearson, Kara Peters, and Mohammed Zikry
Abstract: This article presents the use of Bragg reflection and cladding mode
measurements to independently measure axial strain and the integrity of a Bragg
grating sensor. While the Bragg reflection is known to be sensitive to applied
strain, the cladding modes are shown to be sensitive to expected damage within
the sensor such as microcracking and debonding from the host structure. This phenomenon
allows the intelligent self-testing of the Bragg grating sensor without additional
instrumentation and permits the separate identification of sensor failure from
the failure of the host structure. The growth of cladding modes during degradation
of a Bragg grating is experimentally demonstrated in controlled tension tests
with different fiber-host interface conditions.
Note: this paper was delivered at the 2005 Smart Structures/NDE conference
in San Diego, California, March 8-9, 2005. Troubleshoot
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to top Review of Fiber Optic Accelerometers
By C. Baldwin, J. Niemczuk, J. Kiddy, and T.Salter
Abstract: Over the past decade, the proliferation of fiber optic sensors
and sensing systems has been ever increasing, especially the use of fiber Bragg
grating (FBG) based sensors. These sensors have been mainly relegated to research
applications with a few noted large-scale structural tests. The main sensing parameters
for these tests have been strain and/or temperature. This paper discusses the
development of accelerometers with FBG sensors as the measurement medium. The
discussion includes a brief overview of FBG sensors, the functionality of FBG
sensors as accelerometers, aspects of commercially available instrumentation for
monitoring the accelerometers, and experimental data from three commercially available
accelerometer designs. The purpose of this paper is to provide the modal analysis
community with an understanding of the current state-of-the-art in fiber Bragg
grating sensors for dynamic and vibration testing. (Read
entire article) Copyright
2005 SPA. This paper was delivered at the IMAC XXIII Conference & Exposition on
Structural Dynamics, January 31 - February 3, 2005. Used with permission of Systems
Planning and Analysis, Inc. For more information on SPA, go to their website www.spa.com/aedp.htm Troubleshoot
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to top Techniques of Advanced FBG sensors:
fabrication, demodulation, encapsulation
and their application in the structural
health monitoring of bridges
By Z. Zhou, T. W. Graver, L. Hsu, JP Ou
FBG(Fiber Bragg Grating) sensors have been more
and more accepted by engineers in structural health monitoring(SHM). This paper
has given a brief introduction on the practical techniques of fabrication and
demodulation on FBG sensors. Aiming at the practical applications in infrastructures,
the techniques of FBG encapsulation techniques are developed. And their applications
in the structural health monitoring of bridges are conducted. Finally, some problems
of FBG sensors when used in practical infrastructures are put forward and the
solutions are also suggested. (Read
entire article) Copyright
2004 Beijing Tricom LTD. Posted with permission of Beijing Tricom LTD in China Troubleshoot
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to top Optical Fiber Sensors as Mechanical
Strain Gauges: A Review
By A. Mendez, S. Ferguson, and T.W. Graver
...One of the most common applications
[of optical fiber sensors] is that of strain/stress sensing. A variety of discrete
fiber strain sensors based on Fabry-Perot cavities and fiber Bragg gratings, as
well as distributed techniques based on Brillouin scattering methods have been
developed along with pertinent interrogation electronics and instruments. However,
to many technical communities outside the field of optical fiber technology, the
actual operating principles of these devices and their potential utilization is
not well understood. This lack of familiarity and understanding is preventing
the adoption and diversification of the technology in fields where it can offer
significant functional and commercial benefits over conventional sensing means--
as is the case in the general area of experimental mechanics. In
this paper, we present an overview on the state-of-the-art of optical fiber strain
sensing technology and describe the operating principles and design of different
sensors and interrogation techniques. An analysis of the fundamental strain response
for fiber Bragg grating and Fabry-Perot strain sensors will be presented, and
compared to that of a conventional foil strain gauge. Factors affecting the strain
sensitivity and response of fiber devices such as bonding, sensor placement, strain
field and sensor host interplay will be described. Static and dynamic strain responses
and use in harsh environments will also be described. Note:
this paper was delivered at the 2005 SEM Annual Conference & Exposition on
Experimental and Applied Mechanics in Portland,Oregon, June 7-9, 2005. Back
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Transportation:
Strain survey of an F/A-18 stabilator
spindle using high density Bragg grating arrays
by Stephen McDonald and
Claire Davis For the full article, go to
the DSTO website Troubleshoot
PDF Viewing Back
to top Utilization of Fiber Optic
Bragg Grating Sensing Systems for Health Monitoring in Railway Aplications
By H.Y. Tam, T. Lee, S.L. Ho, T. Haber, T. Graver, A. Mendez
Abstract: We present results of a fiber optic structural health monitoring
(SHM) system on an operational passenger railroad in Hong Kong. The system is
based on a network of FBG sensors that measure strain and temperature in a multitude
of critical locations. The sensors are mounted on guiding rails as well as on
the undercarriage of passenger cars, using specially packaged strain sensors.
The system—which is fully operational and in present service use—is providing
invaluable and timely information about stresses experienced during service, both
static and dynamic, under different operational conditions...(read
entire paper). © 2007
Used, with permission, from the authors. Back to
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