This paper reports on an experimental program of work which investigates the reliability, durability, and packaging of fiber Bragg gratings （FBGs） for application as distributed strain sensors during structural fati...This paper reports on an experimental program of work which investigates the reliability, durability, and packaging of fiber Bragg gratings （FBGs） for application as distributed strain sensors during structural fatigue testing of military platforms. The influence of the FBG fabrication process on sensor reliability is investigated. In addition, methodologies for broad-area packaging and surface-mounting of FBG sensing arrays to defense platforms are developed and tested.展开更多
The ability to operate despite failure will become increasingly important as the use of optical sensor networks grows, and the amount of sensing information to be handled by a sensor network is increasing, especially ...The ability to operate despite failure will become increasingly important as the use of optical sensor networks grows, and the amount of sensing information to be handled by a sensor network is increasing, especially for safety and security applications. In this review, the four categories of protection to allow service to be reestablished after a failure （dedicated/shared and line/path） are thoroughly discussed. This paper also presents an overview of the most representative robust fiber-optic sensor systems, discussing their schemes, pros and cons.展开更多
This paper investigates the application of distributed optical fiber strain sensors to civil engineering structures, because no other tool can satisfactorily detect the location of the unpredictable phenomenon. In fac...This paper investigates the application of distributed optical fiber strain sensors to civil engineering structures, because no other tool can satisfactorily detect the location of the unpredictable phenomenon. In fact, the locations of cracks in the concrete structure are unknown a priori; therefore, a fully distributed sensor is necessary to detect them. The Brillouin optical correlation domain analysis （BOCDA）, which offers high spatial resolution by using stimulated Brillouin scattering along the whole length of the optical fiber, is used in a wide range of civil engineering applications, and the same has undergone significant development over the last decade. In this paper, it is demonstrated how a BOCDA-based strain sensor can be employed to monitor cracks in concrete. Crack monitoring on the surface of the concrete member provides useful information for evaluating stiffness and durability of the structure, particularly for early detection of tiny cracks, which is essential for preventing crack growth and dispersion. The crack-induced strain distribution was analytically investigated, and it was proved that BOCDA can identify even a small crack before its visual recognition by a beam test. Moreover, periodical crack monitoring was successfully executed on a pedestrian deck for five years.展开更多
Hydrogen is one of the next generation energies in the future, which shows promising applications in aerospace and chemical industries. Hydrogen leakage monitoring is very dangerous and important because of its low ig...Hydrogen is one of the next generation energies in the future, which shows promising applications in aerospace and chemical industries. Hydrogen leakage monitoring is very dangerous and important because of its low ignition energy, high combustion efficiency, and smallest molecule. This paper reviews the state-of-art development of the fiber optic hydrogen sensing technology. The main developing trends of fiber optic hydrogen sensors are based on two kinds of hydrogen sensitive materials, i.e. palladium-alloy thin films and Pt-doped WO3 coatings. In this review work, the advantages and disadvantages of these two kinds of sensing technologies will be evaluated.展开更多
We proposed two schemes of generating and localizing dynamic gratings in optical fibers： one is based on the gain saturation in erbium-doped fiber; the other is based on Brillouin scattering in the fiber. By using th...We proposed two schemes of generating and localizing dynamic gratings in optical fibers： one is based on the gain saturation in erbium-doped fiber; the other is based on Brillouin scattering in the fiber. By using these dynamic gratings, fully distributed strain/temperature sensors have been demonstrated. In this presentation, we review the principles, basic schemes, and experimental demonstrations of the novel dynamic grating techniques.展开更多
文摘This paper reports on an experimental program of work which investigates the reliability, durability, and packaging of fiber Bragg gratings （FBGs） for application as distributed strain sensors during structural fatigue testing of military platforms. The influence of the FBG fabrication process on sensor reliability is investigated. In addition, methodologies for broad-area packaging and surface-mounting of FBG sensing arrays to defense platforms are developed and tested.
文摘The ability to operate despite failure will become increasingly important as the use of optical sensor networks grows, and the amount of sensing information to be handled by a sensor network is increasing, especially for safety and security applications. In this review, the four categories of protection to allow service to be reestablished after a failure （dedicated/shared and line/path） are thoroughly discussed. This paper also presents an overview of the most representative robust fiber-optic sensor systems, discussing their schemes, pros and cons.
文摘This paper investigates the application of distributed optical fiber strain sensors to civil engineering structures, because no other tool can satisfactorily detect the location of the unpredictable phenomenon. In fact, the locations of cracks in the concrete structure are unknown a priori; therefore, a fully distributed sensor is necessary to detect them. The Brillouin optical correlation domain analysis （BOCDA）, which offers high spatial resolution by using stimulated Brillouin scattering along the whole length of the optical fiber, is used in a wide range of civil engineering applications, and the same has undergone significant development over the last decade. In this paper, it is demonstrated how a BOCDA-based strain sensor can be employed to monitor cracks in concrete. Crack monitoring on the surface of the concrete member provides useful information for evaluating stiffness and durability of the structure, particularly for early detection of tiny cracks, which is essential for preventing crack growth and dispersion. The crack-induced strain distribution was analytically investigated, and it was proved that BOCDA can identify even a small crack before its visual recognition by a beam test. Moreover, periodical crack monitoring was successfully executed on a pedestrian deck for five years.
基金This work is finically supported by the project of the National Science Foundation of China, NSFC （Number： 60908020, 61290311） and program for the New Century Excellent Talents in University （NCET-10-0664）. Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author（s） and source are credited.
文摘Hydrogen is one of the next generation energies in the future, which shows promising applications in aerospace and chemical industries. Hydrogen leakage monitoring is very dangerous and important because of its low ignition energy, high combustion efficiency, and smallest molecule. This paper reviews the state-of-art development of the fiber optic hydrogen sensing technology. The main developing trends of fiber optic hydrogen sensors are based on two kinds of hydrogen sensitive materials, i.e. palladium-alloy thin films and Pt-doped WO3 coatings. In this review work, the advantages and disadvantages of these two kinds of sensing technologies will be evaluated.
文摘We proposed two schemes of generating and localizing dynamic gratings in optical fibers： one is based on the gain saturation in erbium-doped fiber; the other is based on Brillouin scattering in the fiber. By using these dynamic gratings, fully distributed strain/temperature sensors have been demonstrated. In this presentation, we review the principles, basic schemes, and experimental demonstrations of the novel dynamic grating techniques.
