Search results

1 – 10 of 147
To view the access options for this content please click here
Article
Publication date: 1 March 1998

Vincent A. Handerek

Optical fibre multiplexed sensors are used to make measurements at multiple, discrete locations, usually by sending optical signals between each measurement location and a…

Downloads
651

Abstract

Optical fibre multiplexed sensors are used to make measurements at multiple, discrete locations, usually by sending optical signals between each measurement location and a conveniently positioned optical interrogation instrument. It is rapidly becoming practical to construct multiplexed optical fibre sensor arrays based on in‐fibre Bragg gratings. A Bragg grating can be produced in an optical fibre by writing a periodic variation in the refractive index of the fibre’s core along the axis, using ultra‐violet light. Multiplexing applications will appear ranging from the small scale, with only a few sensors, up to very large scales with hundreds of sensors.

Details

Sensor Review, vol. 18 no. 1
Type: Research Article
ISSN: 0260-2288

Keywords

To view the access options for this content please click here
Article
Publication date: 13 September 2011

Stephen J. Mihailov, Dan Grobnic, Christopher W. Smelser, Robert B. Walker, Ping Lu and Huimin Ding

The purpose of this paper is to present a review of research performed at the Communications Research Centre Canada on sensing applications of femtosecond infrared…

Abstract

Purpose

The purpose of this paper is to present a review of research performed at the Communications Research Centre Canada on sensing applications of femtosecond infrared laser‐inscribed Bragg gratings.

Design/methodology/approach

By using fibre Bragg gratings induced with ultrafast infrared radiation, inscription of high temperature stable sensors in standard and exotic optical waveguides is investigated for a variety of novel applications.

Findings

Generally, femtosecond laser‐induced gratings are effective sensors that can be applied in situations and environments where most fibre optic sensors are not effective.

Originality/value

The paper is a review of existing work already published in the literature and provides an overview of this technology to the reader.

To view the access options for this content please click here
Article
Publication date: 1 June 2005

Robert Bogue

This paper describes a recent collaborative project involving the development of a multiplexed fibre Bragg grating (FBG) sensor system for structural integrity monitoring.

Abstract

Purpose

This paper describes a recent collaborative project involving the development of a multiplexed fibre Bragg grating (FBG) sensor system for structural integrity monitoring.

Design/methodology/approach

The system is described and field trials on both conventional and novel composite bridges are discussed. A FBG sensor‐based structural monitoring system was developed, based on a fluorescent fibre as the optical source. It used a tuneable, fibre‐coupled, Fabry‐Perot filter, actuated by piezoelectric transducers and operated over the bandwidth of the source at up to 250 scans/second. Light from the source was filtered and reflected back from the Bragg gratings, through optical couplers, to eight photodiode detectors. These detected the resulting time‐domain spectra of the sensors in each of the serially connected sensor arrays. The system was tested at City University and then subjected to trials on the Mjosund road bridge in Norway and on West Mill bridge in Oxfordshire, UK, which is the first bridge to be fabricated from a new type of composite material.

Findings

During the Norwegian trials the system was arranged with four or five FBG sensors per channel giving a total of 32 measurement points with eight parallel channels. Twelve conventional foil strain gauges and a number of thermocouples were also installed. Different static and dynamic loads were applied over a period of 18 months and the results showed that the thermally compensated strain data obtained optically matched those from the resistive gauges to within <5 με. During the construction stage of the Oxfordshire bridge, sections of the decking and longitudinal composite support beams were instrumented with 40 FBG sensors with temperature compensation, placed at pre‐selected sites of maximum strain. These exhibited a resolution of ±5 με and an operating range of over ±2,000 με.

Originality/value

This research has shown that multiplexed, multi‐point FBG sensor systems can accurately and reliably monitor both static and dynamic strains in large structures over a range of temperatures and for extended periods of time.

Details

Sensor Review, vol. 25 no. 2
Type: Research Article
ISSN: 0260-2288

Keywords

To view the access options for this content please click here
Article
Publication date: 11 February 2021

Yongxing Guo, Min Chen, Li Xiong, Xinglin Zhou and Cong Li

The purpose of this study is to present the state of the art for fiber Bragg grating (FBG) acceleration sensing technologies from two aspects: the principle of the…

Abstract

Purpose

The purpose of this study is to present the state of the art for fiber Bragg grating (FBG) acceleration sensing technologies from two aspects: the principle of the measurement dimension and the principle of the sensing configuration. Some commercial sensors have also been introduced and future work in this field has also been discussed. This paper could provide an important reference for the research community.

Design/methodology/approach

This review is to present the state of the art for FBG acceleration sensing technologies from two aspects: the principle of the measurement dimension (one-dimension and multi-dimension) and the principle of the sensing configuration (beam type, radial vibration type, axial vibration type and other composite structures).

Findings

The current research on developing FBG acceleration sensors is mainly focused on the sensing method, the construction and design of the elastic structure and the design of a new information detection method. This paper hypothesizes that in the future, the following research trends will be strengthened: common single-mode fiber grating of the low cost and high utilization rate; high sensitivity and strength special fiber grating; multi-core fiber grating for measuring single-parameter multi-dimensional information or multi-parameter information; demodulating equipment of low cost, small volume and high sampling frequency.

Originality/value

The principle of the measurement dimension and principle of the sensing configuration for FBG acceleration sensors have been introduced, which could provide an important reference for the research community.

Details

Sensor Review, vol. 41 no. 1
Type: Research Article
ISSN: 0260-2288

Keywords

To view the access options for this content please click here
Article
Publication date: 18 January 2013

Jiang Qi

The purpose of this paper is to compare the sensing characteristics of uniform fiber Bragg grating (FBG) and tilted fiber Bragg grating (TFBG) by presenting a detailed…

Abstract

Purpose

The purpose of this paper is to compare the sensing characteristics of uniform fiber Bragg grating (FBG) and tilted fiber Bragg grating (TFBG) by presenting a detailed research review. Temperature, axial strain, bending, vibration and refractive index measurands of FBG and TFBG sensor are presented and some significant differences are found.

Design/methodology/approach

Theoretical analysis and practical application in engineering are investigated and compared from other authors' research papers and self analysis. Spectra behavior of both FBG and TFBG are discussed.

Findings

There are found to be significant differences in temperature, axial strain, bending, vibration and refractive index sensing characteristics of FBG and TFBG.

Originality/value

The paper's analysis is comprehensive and clear and provides readers with the sensing characteristics of FBG and TFBG in detail.

To view the access options for this content please click here
Article
Publication date: 1 March 2005

Robert W. Bogue

To describe a new technique, developed in Korea, which extends the operational length of fibre Bragg grating strain and temperature sensors to approximately 50 km. It is…

Abstract

Purpose

To describe a new technique, developed in Korea, which extends the operational length of fibre Bragg grating strain and temperature sensors to approximately 50 km. It is based on distributed Raman amplification.Design/methodology/approach – The system uses a single pump source to achieve distributed Raman amplification in the transmission optical fibre and does not employ an additional broadband light source, as the residual pump power after the transmission fibre is recycled to generate broadband amplified spontaneous emission in an erbium‐doped fibre.Findings – The temperature and strain response of the system was tested by measuring changes in reflection from the sensor which were captured on an optical spectrum analyser, located at the end of a 50 km length of fibre. The thermal sensitivity was found to be 8.2 pm/°C over the range 30‐100°C and a strain sensitivity of 1.1 pm/με was exhibited between 0 and 1,700 με. The measurement resolutions of the system for temperature and strain were estimated at 0.7°C and 8.64 με, respectively. The signal‐to‐noise ratio was approximately 11 dB.Originality/value – This work has shown that the use of distributed Raman amplification can extend the operational length of fibre Bragg grating sensors from around 25 km to at least 50 km, whilst achieving good strain and temperature sensitivities.

Details

Sensor Review, vol. 25 no. 1
Type: Research Article
ISSN: 0260-2288

Keywords

To view the access options for this content please click here
Article
Publication date: 4 January 2019

Cansu Karatas, Boray Degerliyurt, Yavuz Yaman and Melin Sahin

Structural health monitoring (SHM) has become an attractive subject in aerospace engineering field considering the opportunity to avoid catastrophic failures by detecting…

Abstract

Purpose

Structural health monitoring (SHM) has become an attractive subject in aerospace engineering field considering the opportunity to avoid catastrophic failures by detecting damage in advance and to reduce maintenance costs. Fibre Bragg Grating (FBG) sensors are denoted as one of the most promising sensors for SHM applications as they are lightweight, immune to electromagnetic effects and able to be embedded between the layers of composite structures. The purpose of this paper is to research on and demonstrate the feasibility of FBG sensors for SHM of composite structures.

Design/methodology/approach

Applications on thin composite beams intended for SHM studies are presented. The sensor system, which includes FBG sensors and related interrogator system, and manufacturing of the beams with embedded sensors, are detailed. Static tension and torsion tests are conducted to verify the effectiveness of the system. Strain analysis results obtained from the tests are compared with the ones obtained from the finite element analyses conducted using ABAQUS® software. In addition, the comparison between the data obtained from the FBG sensors and from the strain gauges is made by also considering the noise content. Finally, fatigue test under torsion load is conducted to observe the durability of FBG sensors.

Findings

The results demonstrated that FBG sensors are feasible for SHM of composite structures as the strain data are accurate and less noisy compared to that obtained from the strain gauges. Furthermore, the convenience of obtaining reliable data between the layers of a composite structure using embedded FBG sensors is observed.

Practical implications

Observing the advantages of the FBG sensors for strain measurement will promote using FBG sensors for damage detection related to the SHM applications.

Originality/value

This paper presents applications of FBG sensors on thin composite beams, which reveal the suitability of FBG sensors for SHM of lightweight composite structures.

Details

Aircraft Engineering and Aerospace Technology, vol. 92 no. 3
Type: Research Article
ISSN: 1748-8842

Keywords

To view the access options for this content please click here
Article
Publication date: 1 June 2000

L. Everall, A. Gallon and D. Roberts

This paper describes state‐of‐the‐art optical technology, employing Bragg gratings, which has been used to develop an Optical Fibre Strain Sensing System. This system is…

Abstract

This paper describes state‐of‐the‐art optical technology, employing Bragg gratings, which has been used to develop an Optical Fibre Strain Sensing System. This system is capable of providing actual strain and temperature information for new and existing structures. The sensors, written into the core of standard single mode optical fibre, are embedded into the composite material, or surface bonded on to the structure for load monitoring. The system can be used as a design tool for engineers, for composite cure‐monitoring, setting up of rigs etc., or can be used as a health monitoring tool to periodically monitor loading of bridges, buildings and pipelines.

Details

Sensor Review, vol. 20 no. 2
Type: Research Article
ISSN: 0260-2288

Keywords

To view the access options for this content please click here
Article
Publication date: 1 June 2002

Xiaoming Tao

Deals with the optical responses of fibre Bragg grating (FBG) sensors under different modes of deformation. It derives both the polarisation states and reflection spectra…

Abstract

Deals with the optical responses of fibre Bragg grating (FBG) sensors under different modes of deformation. It derives both the polarisation states and reflection spectra of FBGs based on coupled mode equations by considering the deformation perturbations. It conducts numeric simulations, finds that the experimental results agree well with the simulated ones for normal germano‐silicate FBGs under different individual modes of deformations.

Details

International Journal of Clothing Science and Technology, vol. 14 no. 3/4
Type: Research Article
ISSN: 0955-6222

Keywords

To view the access options for this content please click here
Article
Publication date: 28 March 2008

Dimitrios Karalekas

The objective of this study is to investigate the use of a fibre Bragg grating (FBG) sensor for measuring of curing strains that develop during the solidification of a…

Abstract

Purpose

The objective of this study is to investigate the use of a fibre Bragg grating (FBG) sensor for measuring of curing strains that develop during the solidification of a photocurable resin used in 3D microfabrication.

Design/methodology/approach

The followed approach consists of embedding a 1,300 nm FBG into a cylindrical specimen, fabricated into a transparent mould, being exposed to ultraviolet laser light. The further development of the cure induced strains under thermal treatment was also studied by post‐conditioning the cylindrical specimen in an oven at 70°C.

Findings

The experimental results demonstrate the capability of the FBG sensor to provide useful information on the strain build‐up during laser solidification and their post‐cure evolution under the presence of a thermal environment.

Research limitations/implications

Future work should involve the use of smaller diameter FBG sensors in microstereolithography built parts.

Practical implications

It is shown that considerable cure strains are developed at the end of the photo‐polymerisation process that eventually can affect the structural resolution of final parts fabricated by microstereolithography.

Originality/value

The presented method can be used to investigate other photopolymers used in micro‐stereolithography.

Details

Rapid Prototyping Journal, vol. 14 no. 2
Type: Research Article
ISSN: 1355-2546

Keywords

1 – 10 of 147