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A fast interrogation system of FBG sensors based on low loss jammed-array wideband sawtooth filter
摘要： In this paper, a low loss jammed-array wideband sawtooth (JAWS) filter is built based on a finite reflection virtually imaged array (FRVIA) which has a lower reflectivity of the exit surface compared to a virtually imaged phased array (VIPA). This filter can be used as an edge filter to interrogate the fiber Bragg grating (FBG) sensors. A fast FBG sensing system is set up to detect the strain wave of iron pipe to demonstrate the use of this interrogator. The result shows that the JAWS based interrogation system has advantages of high speed, low loss and high sensitivity.
关键词： JAWS filter,Fiber Bragg grating (FBG) interrogator,Finite reflection virtually imaged array
更新于2025-11-28 14:24:03
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A Rotation Independent In-Place Inclinometer/Tilt Sensor Based on Fiber Bragg Grating
摘要： The inclinometer is one of the most important instruments used in geotechnical engineering. The inclinometer is installed into a borehole to monitor the angle of inclination at regular intervals along the borehole to profile the land/soil displacement. In this paper, a novel design of an in-place inclinometer utilizing fiber Bragg grating (FBG) sensor technology is presented. The presented inclinometer is highly sensitive and has an angle measurement resolution of 0.006°. The conventional inclinometers may be twisted involuntarily due to the force that they experience during installation. This twisting may hamper the measurement accuracy of inclinometers. The performance of the proposed FBG-based in-place inclinometer is independent of twisting; hence, its accuracy remains intact even if it is twisted.
关键词： soil displacement/deformation,Borehole inclinometer,tilt sensor,fiber Bragg grating (FBG),land-slide monitoring,fiber optic sensor,in-place inclinometer
更新于2025-09-23 15:22:29
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Experimental Research on Sensing Characteristics of Adhesive-encapsulated FBG under Alcohol-disinfection Environment
摘要： Fiber Bragg grating (FBG) has proven to be the most suitable sensing element for force feedback of surgical robots because of its special advantages such as small size and physical robustness. In current reports, researchers packaged FBGs in surgical instrument by attaching them to external surface or embedding into shaft grooves by using adhesive because its good liquidity and operability compared with other packaging methods such as metal package and glass solder package, and the adhesive is often without covering because strict space requirement of tiny surgical instruments. However, due to the need of repeated disinfection, surgical instruments have to be exposed to chemical disinfectant excessively, which may leads to chronic corrosion of adhesive, and thus influences the sensing characteristics of the integrated FBGs. To address this concern, this paper investigates the sensing characteristics of adhesive-encapsulated FBG under disinfection environment. We simulated a common disinfection environment by using 75% alcohol, and three adhesive-encapsulated FBGs were soaked in it for long term. The sensing performances of FBGs have been tested periodically and the experimental results demonstrate that the FBGs are available with good sensing characteristics within the first 50 days. While after 50 days, the sensing performances of the three FBGs become worse gradually, and finally the adhesive layers of the three FBGs completely detached from the specimen in the 75th day, 80th day and 95th day, respectively. We hope the investigation could provide valuable reference for better application of FBG in force feedback of surgical robots.
关键词： Fiber Bragg grating (FBG),robot sensing,force feedback,alcohol-disinfection environment,surgical robot
更新于2025-09-23 15:22:29
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Temperature Measurement of Electromagnetic Launcher Rails Based on FBG
摘要： Rails worked under a harsh environment in the electromagnetic launching. Measurement of temperature at or close to the rail-and-armature interface of an electromagnetic launch (EML) is capability that would provide a significant insight into the EML performance. This interface is difficult to access and requires any sensor to tolerate sliding contacts, high electrical currents, and extreme temperatures. As a result, the existing temperature sensor technology has not been successful in providing data at that location. The development of the fiber Bragg grating (FBG) may provide a potential solution for this requirement. By designing and building a temperature measurement system based on FBG, we can collect dynamic temperature data of the rail during the launch. This paper establishes a model of transient thermal field of EML, calculates the variation of rail temperature under the effect of the Joule heat, and compares with the measurement result. After adding the model in the case of the protection package of FBG temperature sensor, the simulation data agrees well with the test data, and the sensors do not been destroyed even disturbed. All of the above prove that this method is feasible, and the sensors can be used in the following tests.
关键词： fiber Bragg grating (FBG),thermal field,Joule heat,temperature measurement,Electromagnetic launch (EML),rails
更新于2025-09-23 15:22:29
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Strain Monitoring on PHC Pipe Piles Based on Fiber Bragg Grating Sensors
摘要： Fiber Bragg grating (FBG) sensors emerged as a relatively new strain-sensing technology for civil engineering applications. This study presents a field test to assess the feasibility of FBG sensors in monitoring the strain profile of prestressed high-strength concrete (PHC) pipe piles during installation. Two open-ended PHC pipe piles were instrumented with FBG sensors and then driven into the ground using a hydraulic jacking machine. To measure the strain profile along the test piles, nine FBG sensors were arranged in a single optical fiber and then mounted on one pile at the opposite side to monitor the strain at different levels as a function of wavelength shift. The procedure for installing the FBG sensors along the PHC pipe piles is introduced first. Next, the distribution of the axial forces and average side shear stresses that were evaluated from the strain measurements of the FBG sensors are discussed. The field test results indicate that the FBG sensor system was suitable for monitoring the strain state of PHC pipe piles during installation. The axial forces and side shear stresses along the test piles were influenced significantly by the penetration depth and the local soil resistance.
关键词： Fiber Bragg grating (FBG) technology,Jacking method,Strain monitoring,Prestressed high-strength concrete (PHC) pipe pile
更新于2025-09-23 15:22:29
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Nuclear Power Plant Prestressed Concrete Containment Vessel Structure Monitoring during Integrated Leakage Rate Testing Using Fiber Bragg Grating Sensors
摘要： As the last barrier of nuclear reactor, prestressed concrete containment vessels (PCCVs) play an important role in nuclear power plants (NPPs). To test the mechanical property of PCCV during the integrated leakage rate testing (ILRT), a fiber Bragg grating (FBG) sensor was used to monitor concrete strain. In addition, a finite element method (FEM) model was built to simulate the progress of the ILRT. The results showed that the strain monitored by FBG had the same trend compared to the inner pressure variation. The calculation results showed a similar trend compared with the monitoring results and provided much information about the locations in which the strain sensors should be installed. Therefore, it is confirmed that FBG sensors and FEM simulation are very useful in PCCV structure monitoring.
关键词： structure health monitoring (SHM),finite element method (FEM),integrated leakage rate test (ILRT),fiber Bragg grating (FBG),prestressed concrete containment vessel (PCCV)
更新于2025-09-23 15:21:01
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Superwide-Range Fiber Bragg Grating Displacement Sensor Based on an Eccentric Gear: Principles and Experiments
摘要： Aiming at the large displacement monitoring needs of slope, road, and bridge engineering, a new method concerning the superwide-range fiber Bragg grating (FBG) displacement sensor based on eccentric gear was investigated. The structure of the sensor was designed and the formula for the wavelength-displacement relationship was established via waveform fitting from calibration tests. The lateral displacement of a first-story shear wall was successfully monitored in a hysteresis test of a steel frame–reinforced concrete infill wall. A FBG relative displacement sensor was developed refitting a superwide-range fiber Bragg grating displacement sensor based on eccentric gear. The refitted sensor was applied in a self-repairing performance test of a shape memory alloy (SMA) strengthened concrete beam. The monitoring results of the crack were compared with the results of an integrated test instrument, and the results showed that the sensor exhibited very good accuracy. The innovative FBG displacement sensor has a low influence on the structure, strong practicability, and good prospects for engineering applications.
关键词： Crack measurement,Fiber Bragg grating (FBG),Superwide-range displacement monitoring,Eccentric gear,Displacement sensor
更新于2025-09-04 15:30:14
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[ASME ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering - Madrid, Spain (Sunday 17 June 2018)] Volume 11B: Honoring Symposium for Professor Carlos Guedes Soares on Marine Technology and Ocean Engineering - Investigation on Temperature Compensation of Fiber Bragg Grating Sensors for Hull Monitoring
摘要： Hull monitoring system with Fiber Bragg Grating (FBG) sensors increasingly receives people's attentions. However, for the ship hull monitoring, the deformation of hull girder changes a lot as is subjected to a huge temperature variation. Therefore, the compensation method with only FBG temperature self-correction is not suitable for the hull monitoring sensors because no material thermal expansion effects are reasonably included. In this paper, the new compensation method of hull monitoring FBG sensor based on the sensor theory with both FBG temperature self-correction and steel thermal expansion effects correction is studied. The coupled compensation method suitable for hull monitoring sensor is obtained by theoretical derivation. As the comparison, the coupled compensation experiment was carried out. The results show that the relative error under the temperature compensation method is large in the case of drastic strain and temperature changes, and the correction results of the tested method will be closer to the true level.
关键词： temperature compensation,coupled compensation method,steel thermal expansion,hull monitoring,Fiber Bragg Grating (FBG) sensors
更新于2025-09-04 15:30:14
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A Fiber Bragg-Grating-Based Miniature Sensor for the Fast Detection of Soil Moisture Profiles in Highway Slopes and Subgrades
摘要： A fiber Bragg grating (FBG)-based aluminum oxide tube packed sensor (ATPS) was developed for the fast detection of the soil moisture profile in highway slopes and subgrades. The novel ATPS consists of an aluminum oxide tube with a diameter of 5 mm, an optical fiber containing a quasi-distributed FBG sensors, a “U”-shaped resistance wire, and a flange. There are four 0.9-mm diameter holes in the ATPS. Laboratory experiments were carried out to calibrate the relationship between the thermal response of ATPS and the soil moisture content. Two laboratory rainfall validation model tests were performed to validate the ATPS for capturing the soil moisture profile in highway slopes and subgrades. During the validations, the accuracy of the ATPS was quantified, and water infiltration through grassy and grassless ground surfaces were investigated. The calibrations indicate that the ATPS can detect and record real-time changes in the highway slope and subgrade moisture after rainfall, and reveal the most dangerous zones that occur at the connection between different construction materials. The average measurement accuracy of soil moisture monitoring was 0.015 m3/m3. Please note that the connection is where cracks form easily and the soil hydraulic conductivity increases significantly. The test results also indicate that grassy cover (lawn) significantly prevents water infiltration during the first few minutes of rainfall (twelve minutes in this study), after which, however, the infiltration rate drops sharply. The influence of lawn on water infiltration depends on the soil structure, hydraulic conductivity, and rainfall time. In summary, due to its small size and fast detection, the ATPS is a portable probe that can be used for moisture monitoring in highway slopes and subgrades.
关键词： temperature sensing,aluminum oxide tube packed sensor (ATPS),highway slope and subgrade,fiber Bragg grating (FBG),soil moisture
更新于2025-09-04 15:30:14