Measurement of the Thermal Expansion for Space Structures Using Fiber Bragg Grating Sensors and Displacement Measuring Interferometers

2008 ◽  
Author(s):  
Hong-Il Kim ◽  
Lae-Hyong Kang ◽  
Jae-Hung Han
Keyword(s):  
Fiber Bragg Grating ◽  
Real Time ◽  
Deformation Monitoring ◽  
Space Environment ◽  
Space Structures ◽  
Bragg Grating ◽  
Environment Change ◽  
Time Deformation ◽  
Fiber Bragg Grating Sensors ◽  
Fbg Sensors

Dimensional stability of the space structures, such as large telescope mirrors or metering substructures, is very important because even extremely small deformations of these structures might degrade the optical performances. Therefore, precise deformation data of the space structures according to environment change are required to design these structures correctly. Also, real-time deformation monitoring of these structures in space environment is demanded to verify whether these structures are properly designed or manufactured. FBG (fiber Bragg grating) sensors are applicable to real time monitoring of the space structure because they can be embedded onto the structures with minimal weight penalty. In this research, therefore, thermal deformation measurement system for the space structures, composed of FBG sensors for real time strain measurement and DMI (displacement measuring interferometers) for accurate specimen expansion data acquisition, is developed. Thermal strains measured by distributed FBG sensors are evaluated by the comparison with the strains obtained by highly accurate DMI.

Fiber Bragg grating sensor-based monitoring strategy for slope deformation in centrifugal model test

Sensor Review ◽  
2019 ◽  
Vol 39 (1) ◽  
pp. 71-77 ◽  
Author(s):  
Yongxing Guo ◽  
Jianjun Fu ◽  
Longqi Li ◽  
Li Xiong
Keyword(s):  
Fiber Bragg Grating ◽  
Real Time ◽  
Model Test ◽  
Bragg Grating ◽  
Monitoring Strategy ◽  
Content Type ◽  
Centrifugal Model Test ◽  
Time Deformation ◽  
Fbg Sensors ◽  
Centrifugal Model

Purpose Centrifugal model tests can accelerate the characterization of landslides and demonstrate the form of slope failure, which is an important measure to research its instability mechanisms. Simply observing the slope landslide before and after a centrifugal model test cannot reveal the processes involved in real-time deformation. Electromagnetic sensors have severed as an existing method for real-time measurement, however, this approach has significant challenges, including poor signal quality, interference, and complex implementation and wiring schemes. This paper aims to overcome the shortcomings of the existing measurement methods. Design/methodology/approach This work uses the advantages of fiber Bragg grating (FBG) sensors with their small form-factor and potential for series multiplexing in a single fiber to demonstrate a monitoring strategy for model centrifugal tests. A slope surface deformation displacement sensor, FBG anchor sensor and FBG anti-slide piling sensor have been designed. These sensors are installed in the slope models, while centrifugal acceleration tests under 100 g are carried out. Findings FBG sensors obtain three types of deformation information, demonstrating the feasibility and validity of this measurement strategy. Originality/value The experimental results provide important details about instability mechanisms of a slope, which has great significance in research on slope model monitoring techniques and slope stability.

scholarly journals Real-Time Train Wheel Condition Monitoring by Fiber Bragg Grating Sensors

2011 ◽  
Vol 8 (1) ◽  
pp. 409048 ◽  
Author(s):  
Chuliang Wei ◽  
Qin Xin ◽  
W. H. Chung ◽  
Shun-yee Liu ◽  
Hwa-yaw Tam ◽  
...  
Keyword(s):  
Fiber Bragg Grating ◽  
Real Time ◽  
Visual Inspection ◽  
Condition Index ◽  
Bragg Grating ◽  
Time System ◽  
Real Time System ◽  
Fiber Bragg Grating Sensors ◽  
Extensive Field ◽  
The Cost

Wheel defects on trains, such as flat wheels and out-of-roundness, inevitably jeopardize the safety of railway operations. Regular visual inspection and checking by experienced workers are the commonly adopted practice to identify wheel defects. However, the defects may not be spotted in time. Therefore, an automatic, remote-sensing, reliable, and accurate monitoring system for wheel condition is always desirable. The paper describes a real-time system to monitor wheel defects based on fiber Bragg grating sensors. Track strain response upon wheel-rail interaction is measured and processed to generate a condition index which directly reflects the wheel condition. This approach is verified by extensive field test, and the preliminary results show that this electromagnetic-immune system provides an effective alternative for wheel defects detection. The system significantly increases the efficiency of maintenance management and reduces the cost for defects detection, and more importantly, avoids derailment timely.

Metrological Performances of Fiber Bragg Grating Sensors and Comparison with Electrical Strain Gauges

2011 ◽  
Vol 495 ◽  
pp. 53-57
Author(s):  
Marco Borotto ◽  
Enrico De Cais ◽  
Marco Belloli ◽  
Andrea Bernasconi ◽  
Stefano Manzoni
Keyword(s):  
Fiber Bragg Grating ◽  
Thermal Effects ◽  
Measurement Accuracy ◽  
Signal To Noise Ratio ◽  
Bragg Grating ◽  
Light Spectrum ◽  
Static Tests ◽  
Measurement Systems ◽  
Fiber Bragg Grating Sensors ◽  
Fbg Sensors

The fiber Bragg grating sensors (FBGs) have been recently introduced: they present a photorecord grating on the fiber itself, which allows the reflection of a certain wavelength of the input light spectrum. The applied strain is estimated relying on changes of the reflected wavelength. One of the possible applications that has prompted us to study this type of sensors is the possibility to create smart dynamometric structures based on carbon fiber by embedding FBGs. Many papers are available in literature about some applications with smart structures but there is not yet an appropriate metrological characterization about these FBG sensors, their strengths and weaknesses: for these reasons it was deemed useful making several tests on FBG sensors in terms of measurement accuracy, signal to noise ratio, ability to compensate for thermal effects and their behavior for dynamic applications. All these results have been compared to electrical strain gauge ones, which represent the actual reference strain measurement systems. The various solutions to compensate for thermal effects have offered several information for further analyses and the basis for a future use of these sensors for static or semi-static tests. Being fully aware of FBGs characteristics allows to draw down guidelines about their integration in composite materials for the most different applications, understanding in a better way the sensor response.

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