Detection of Ceramic Cracks Using a Distributed High-Resolution Brillouin Fiber Optic Sensor

A distributed sensor system is highly desirable for detecting, locating, and monitoring fine cracks at unknown locations in advanced ceramics. This paper presents a distributed high-resolution fiber optic sensor based on the Brillouin scattering principle, and its application in ceramic crack detection for the first time. The existence of cracks, together with their locations, is identified by measuring the strain distribution on a sensing fiber bonded to the ceramic surface. By employing the innovative coherent probe-pump interaction technique, the Brillouin sensor developed in this study achieves a high spatial resolution (100 mm) and measurement accuracy. Capable of detecting and locating fine cracks less than 40 μm, the efficacy of the distributed Brillouin fiber optic sensor is demonstrated through experiments

Brillouin spectral deconvolution method for centimeter spatial resolution and high-accuracy strain measurement in Brillouin sensors

This paper was published in Optics Letters and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/abstract.cfm?URI=ol-30-7-705. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.Shahraam Afshar V., Xiaoyi Bao, Lufan Zou, and Liang Che

Dependence of the Brillouin frequency shift on strain and temperature in a photonic crystal fiber

This paper was published in Optics Letters and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/abstract.cfm?URI=ol-29-13-1485. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.Lufan Zou, Xiaoyi Bao, Shahraam Afshar V., Liang Che

Subpeaks in the Brillouin loss spectra of distributed fiber-optic sensors

This paper was published in Optics Letters and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/abstract.cfm?URI=ol-30-10-1099. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under lawYidun Wan, Shahraam Afshar V., Lufan Zou, Liang Chen and Xiaoyi Ba

Novel Fiber Optic Technology Monitors In-Slot Vibration and Hot Spots in an Air-Cooled Gas Generator

Technical BriefsGas-fired and air-cooled generators are subjected to continuous start-stop-load cycles related to thermal/mechanical stresses, and continuous vibration. The machines are designed to run at highly efficient material use and close to its design limit. One big concern relates to hot spots in the stator core where thousands of insulated carbon steel laminates are tightly pressed and clamped together. Damaged insulation can cause large Eddy currents to flow leading to core damage or machine shut down

Novel Fiber Optic Technology Monitors In-Slot Vibration and Hot Spots in an Air-Cooled Gas Generator

Technical BriefsGas-fired and air-cooled generators are subjected to continuous start-stop-load cycles related to thermal/mechanical stresses, and continuous vibration. The machines are designed to run at highly efficient material use and close to its design limit. One big concern relates to hot spots in the stator core where thousands of insulated carbon steel laminates are tightly pressed and clamped together. Damaged insulation can cause large Eddy currents to flow leading to core damage or machine shut down

Demonstration of the detection of buckling effects in steel pipelines and beams by the distributed Brillouin sensor

We conducted the strain measurements to monitor steel pipe buckling for the first time using distributed Brillouin sensor system. Two specimens (steel pipeline and beam) were prepared by locally thinning the inner wall to provoke buckling. Fibre was laid along the external walls of the specimens. Strain gauges were glued in thinned wall area. An axial load was applied to the specimens and increased while compressive strain was measured by both Brillouin sensor and the strain gauges. The Brillouin sensor measurements showed the convolution of the all the strain distribution within the spatial resolution, the fitting Brillouin peak corresponds to the average strain over the spatial resolution, hence its reading can be smaller than the strain gauge reading depending on the location. With the Brillouin sensors, we observed compression in the whole specimens while elongation was detected in the neighbourhood of the thinned wall at onset of the buckling for the first time. The buckling was identified and localized with the Brillouin sensor measurement

Pipeline buckling detection by the distributed Brillouin sensor

We conducted strain characterization experiment to monitor steel pipe buckling for the first time using distributed Brillouin sensor system. One specimen was prepared by locally thinning the inner wall to initiate buckling. An axial load was applied to the specimen and increased while compressive strain was measured by both Brillouin sensor and the strain gauges. With the Brillouin sensors, we observed compression in the whole specimen while elongation was detected in the neighbourhood of the thinned wall at onset of the buckling for the first time. The buckling was identified and localized with the Brillouin sensor measurement

Detection of buckling in steel pipeline and column by the distributed Brillouin sensor

We conducted a strain characterization experiment to monitor steel pipe and column buckling for the first time using a distributed Brillouin sensor system. Two specimens (steel pipe and column) were prepared by locally thinning the inner wall to initiate buckling. An axial load was applied to the specimens and increased while compressive strain was measured by both Brillouin sensor and strain gauges. With the Brillouin sensor, we observed compression on the whole specimens while elongation was detected in the neighborhood of the thinned wall at onset of the buckling. Both tension and compression are measured simultaneously from the same spectrum. This capability to extract both informations at the same time makes the Brillouin sensor a unique tool for structural health monitoring. The buckling was identified and localized thanks to this original approach