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1999 | Buch

Fiber optic sensors in concrete structures: a review Kapitel lesen Erstes Kapitel lesen

Optical Fiber Sensor Technology

Applications and Systems

herausgegeben von: Professor K. T. V. Grattan, Professor B. T. Meggitt

Verlag: Springer US

Buchreihe : Optoelectronics, Imaging and Sensing

Enthalten in: Professional Book Archive

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Über dieses Buch

Systems and Applications in Optical Fiber Sensor Technology The essential technology which underpins developments in optical fiber sensors continues to expand, and continues to be driven to a very large extent by advances in optoelectronics which have been produced for the ever-expanding optical com­ munications systems and networks of the world. The steps forward in the technol­ ogy, often accompanied by a reduction in the price of associated components, have been, and continue to be, adapted for use in a wide variety of optical fiber sensor systems. These include, for example, the use of photoinduced gratings as fiber sensor components, coupled with the wider availability of shorter wavelength lasers, bright luminescent sources and high-sensitivity detectors which have opened up new possibilities for both novel fiber optic sensor applications and new sensing systems. This is to be welcomed at a time when, coupled with integrated optic miniaturized devices and detectors, real possibilities of systems integration, at lower cost and increased utility, can be offered. The fiber laser, and the expansions of the types and availability of the doped fiber on which it is based, offer further examples of the integration of the essential components of advanced optical sensor systems, fitted for a new range of applications.

Inhaltsverzeichnis

Frontmatter
1. Fiber optic sensors in concrete structures: a review
Abstract
The overall deterioration of the national civil infrastructure due to aging and usage beyond the anticipated loads and lifetimes for which it was designed, combined with the increasing cost of maintenance and repair, has resulted in the need for improved techniques for non-destructive evaluation of the structural health of reinforced concrete. A recent review of the available statistics reveals that almost 40% of United States bridges are ‘structurally deficient’ or ‘functionally obsolete’ [1]. New reinforced concrete constructions would also benefit from in situ structural monitors which could detect a decrease in performance or imminent failure, thereby optimizing lifetimes without compromising safety. Finally, although modeling the behavior of some structures made from well-characterized materials is fairly accurate, the use of new materials, unusually complex designs, or variability in strength-related factors such as void fraction or moisture content can lead to unexpected structural weakening, damage or failure. The inadequacy of the nation’s highways, bridges, etc. prompted the initiation in 1993 of a National Science Foundation program, with the goal of developing new technologies aimed at ‘prolonging the life and enhancing the capacity of our existing and future civil infrastructure systems’ [2]. In response to the increased need, various techniques are being developed, and some of the most promising are based on the use of fiber optic sensors (FOS).
C. I. Merzbacher, A. D. Kersey, E. J. Friebele
2. The application of optical fiber sensors in advanced fiber reinforced composites. Part 1: Introduction and issues
Abstract
Advanced fiber reinforced composites (AFRCs) are a class of materials which are made up of a reinforcing phase and a matrix phase. The reinforcing phase can be short fibers or continuous fibers. Typical examples of fibers which are used include carbon, glass, silicon carbide and polyaramid. The matrix phase can be a thermoplastic, thermoset, ceramic or metal. A summary of selected properties for engineering materials is presented in Table 2.1. With reference to Table 2.1, it is readily apparent that the specific properties (property of interest divided by the density) of AFRCs are superior to those of other engineering materials. This makes AFRCs ideal materials for primary and secondary load-bearing applications where weight is at a premium. Hence there is extensive utilization for aerospace and other transport-based applications. The drive to reduce the overall weight of AFRCs has resulted in the development of hollow glass and carbon fibers.
G. F. Fernando, P. A. Crosby, T. Liu
3. The application of optical fiber sensors in advanced fiber reinforced composites. Part 2: Cure monitoring
Abstract
Optical-fiber-based cure monitoring in composites or resin systems used in the production of composites can be classified into qualitative or quantitative techniques. In the qualitative approach, correlation is sought between a specified property of the resin as a function of processing time and conditions. For example, the change in the refractive index of the resin system as a function of cure.
P. A. Crosby, G. F. Fernando
4. The application of optical fiber sensors in advanced fiber reinforced composites. Part 3: Strain, temperature and health monitoring
Abstract
The virtues of advanced fiber-reinforced composites (AFRCs) were highlighted in the previous chapters. A major concern with the use of AFRCs is the detection of damage within these materials. AFRCs can sustain significant internal damage before the nature of the damage is visible on the surface. In general, this is because it is the surface which is opposite to the impact surface, i.e. the tensile face which sustains the bulk of the damage. With reference to aerospace structures, impact damage can be induced by bird-strikes, damage from debris and accidental impacts from tools being dropped on the structure. In the case of fatigue damage, the design criteria which are used for these materials ensure that the operating loads are well below those required to initiate damage. However, an issue to note is that aerospace structures may be under a state of dynamic stress when the impact event takes place. There is sufficient evidence now to suggest that the damage mechanics when a composite is impacted under load are different, and the degree of damage is more significant, when compared with conventional impact testing [1]. It is also worth bearing in mind that expensive sensor systems may not be a prudent investment if the sensor is damaged when it receives the first impact.
T. Liu, G. F. Fernando
5. Mathematical techniques in fiber optic sensor applications
Abstract
There is a continuing need for high quality and repeatable measurement techniques for application in a wide variety of industries, and with that the requirement for reliable and trustworthy instrumentation. Fiber optics have a significant part to play in achieving this goal and could result in an opportunity for cost savings, which increases the competitive potential, with benefits being passed on to the customer. Further, the meeting of increased legislative requirements world-wide are often seen to be driving the field, especially in safety and environmental matters. The technology has developed rapidly in recent years, and is now being used by physicists, chemists, engineers and biologists, as well as those comparatively untrained in the fundamentals of the subject. With the wide variety of techniques (which include optical fiber systems) available to these investigators, it is essential that there is a clear understanding of the appropriate guidelines for the selection and use of any particular method of instrumentation, and its limitations as well as its desirable features. Also, the degree to which it is ‘user friendly’ can considerably influence its acceptability for any specific application.
K. T. V. Grattan, B. M. A. Rahman
6. Polarimetric distributed optical fiber sensing
Abstract
Distributed optical fiber sensing (DOFS) is a technique which utilizes the very special properties of the optical fiber to make simultaneous measurements of both the spatial and temporal behavior of a measurand field [1, 2]. As such, it provides an extra dimension in the measurement process, leading to finer monitoring and control, and to a new level of understanding, especially in regard to the behavior of large structures. Thus, we may expect to measure spatial distributions with a resolution 0.1–1 m over a distance of 100 m, to an accuracy of ~1%.
A. J. Rogers
7. Optical current sensor technology
Abstract
The principles of optical and optical fiber current sensor technology have been known for some considerable time, and some of the earliest papers on optical fibre measurement techniques have considered this topic. The general advantages of the use of optical technology were discussed by Rogers [1] in an earlier volume, in which the essential principles of the methods available and a description of some of the essential technologies were described. This builds upon that introduction, and discusses in some detail the optical current sensor devices and technology advances which have been developed in recent years. Optical current sensors (OCSs) show several important features when compared with conventional current transformers (CTs), such as their having highly effective isolation from high line potentials offered by the dielectric nature of the optical fibers, freedom from the saturation effect which may be observed in conventional transformers, the potential to make measurements in high voltage and/or high magnetic induction noise fields, a high linear response over a wide frequency bandwidth, a remote, high-speed measurement capability for monitoring or metering purposes, and the fact that they are compact and light-weight measuring devices, available at potentially low cost.
K. T. V. Grattan, Y. N. Ning
8. Microbend fiber optic sensors
Abstract
The microbend sensor was one of the earliest fiber optic sensors. Microbend losses have always been a curse to the fiber optic cable designer, but it is this very same microbend loss effect in optical fibers which was exploited by the microbend sensor designer who adapted the microbend effect to the measurement of many physical parameters and physical variables such as temperature and pressure.
John W. Berthold III
9. Intrinsic position sensing using optical fiber and coherence domain polarimetry
Abstract
Detection of the physical position of an object is one of the most important sensing applications in industry and engineering. Not only is the gauging of physical dimensions with such position sensor systems important in its own right, but the monitoring of many operational and control parameters in engineering applications can also be converted into position sensing by use of various transducer systems.
S. Chen, B. T. Meggitt
10. Commercial activity in optical fiber sensors
Abstract
In a dynamic field such as that of optical fiber sensing (OFS) and measurement, it is particularly important for the researcher, instrumentation developer, manufacturer, supplier and end user to be fully aware of the existence of, and potential for the use of, the rapidly developing technology that is available. It is effectively impossible to attend all the relevant meetings, conferences, trade shows and exhibitions, and at the same time conduct normal business, and synopses of data and developments are particularly useful. Thus their essential value is seen as providing a summary of the information required on developments and trends, and presenting the data in an accessible and quickly digestible form.
Z. Y. Zhang, K. T. V. Grattan
Backmatter
Metadaten
Titel
Optical Fiber Sensor Technology
herausgegeben von
Professor K. T. V. Grattan
Professor B. T. Meggitt
Copyright-Jahr
1999
Verlag
Springer US
Electronic ISBN
978-1-4757-6077-4
Print ISBN
978-1-4419-4736-9
DOI
https://doi.org/10.1007/978-1-4757-6077-4