scholarly journals Strain Conditions Monitoring on Corroded Prestressed Steel Strands in Beams Based on Fiber Bragg Grating Sensors

Sensors ◽  
2020 ◽  
Vol 20 (8) ◽  
pp. 2288
Author(s):  
Guo-Xi Fan ◽  
Fan-Tong Lin ◽  
Peng Li ◽  
Ji-Gang Han ◽  
Huai-Shuai Shang ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fiber Bragg Grating ◽  
Residual Strain ◽  
Fatigue Performance ◽  
Bragg Grating ◽  
Loading Mode ◽  
Steel Strand ◽  
Fbg Sensors ◽  
Corrosion Of Steel

Fiber Bragg Grating (FBG) sensors, with excellent properties, have been widely adopted to monitor the mechanical parameters in civil engineering in recent years. On the other hand, the current study on fatigue performance of corroded prestressed steel strands is still limited, and this is mainly because the long-term strain conditions monitoring is difficult to conduct. Based on the aforementioned considerations, a total of six beam specimens were fabricated in this study. The loading mode of four points bending was adopted in the form of sinusoidal waves in the experiments. On basis of the experimental results, it can be concluded that the fatigue life of the beam decreases sharply with the increase of the corrosion rate of steel strands. Besides, with the increase of the maximum fatigue load, the fatigue life of the beam will decrease significantly. Furthermore, the existing fatigue damage of steel strand inside the beam before corrosion may further accelerate its fatigue failure. As a result, the fatigue life of the beam is reduced because of the stress concentration. Under the same external load, the strain increment and the residual strain of steel strands in the stages of loading and unloading after corrosion increase significantly compared with other stages, while the existing residual strain always shows an increasing trend at various static loading stages. Therefore, the corrosion of steel strand seriously affects not only its mechanical properties, but also its fatigue performance. Finally, the FBG sensors are capable of measuring the steel strand strain, as well as the long-term strain conditions.

Study on Buried Pipeline Security and Early-Warning System in Landslide Area Based on Fiber Bragg Grating Sensors

2008 ◽  
Author(s):  
Jianping Liu ◽  
Hongju Wang ◽  
Jianbin Hao ◽  
Pengchao Chen ◽  
Muyang Ai
Keyword(s):  
Fiber Bragg Grating ◽  
Electromagnetic Interference ◽  
Surface Displacement ◽  
Warning System ◽  
Bragg Grating ◽  
Buried Pipeline ◽  
Fbg Sensors ◽  
Long Term Monitoring ◽  
Term Monitoring

Compared with electric sensors, Fiber Bragg Grating (FBG) sensors are immune to electromagnetic interference, corrosion resistant, small in size and light in weight. Therefore, FBG sensors are easy to bury into geotechnical soil mass, measuring strain and temperature simultaneously. Focused on buried pipeline integrity, a type of sensing network made up of FBG sensors is introduced in this paper, monitoring pipeline strain, landslide surface displacement and inner displacement. An application of the sensing network to a huge landslide affecting a gas mainline is also introduced. The field experimental data show that, the FBG sensors have many advantages such as good real-time monitoring ability, flexible to develop sensing network, convenient to realize long-term monitoring. Moreover, the FBG sensors give reliable long-term monitoring data of pipeline strain and surface and inner displacement of the landslide, which provide the basis to evaluate pipelines integrity affected by landslides.

Investigation on Temperature Compensation of Fiber Bragg Grating Sensors for Hull Monitoring

2018 ◽  
Author(s):  
Ruiqi Ma ◽  
Guoqing Feng ◽  
Huilong Ren ◽  
Peng Fu ◽  
Shuang Wu ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Fiber Bragg Grating ◽  
Temperature Compensation ◽  
Compensation Method ◽  
Bragg Grating ◽  
Theoretical Derivation ◽  
Temperature Changes ◽  
Hull Girder ◽  
Fbg Sensor ◽  
Fbg Sensors

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.

Vibration Fatigue Test Based on Fiber Bragg Grating Sensors and HHT

2013 ◽  
Vol 328 ◽  
pp. 193-197
Author(s):  
Si Jin Xin ◽  
Zhen Tong
Keyword(s):  
Titanium Alloy ◽  
Fiber Bragg Grating ◽  
Fatigue Test ◽  
Alloy Sheet ◽  
Bragg Grating ◽  
Metal Fatigue ◽  
Hilbert Huang Transform ◽  
Time Frequency ◽  
Vibration Fatigue ◽  
Fbg Sensors

The metal fatigue is an important factor to cause an accident in machine operation, so metal fatigue test is a significant procedure in manufacturing. Fiber Bragg Grating (FBG), as an innovative sensor, has been applied to the measurement of various rotating machines. In this paper, the time-frequency analysis is used to detect the fatigue feature of a titanium alloy measured by FBG sensors. Furthermore, the Hilbert-Huang transform (HHT) is more effective to observe the fatigue limit of the titanium alloy sheet, compared to the Wavelet transform (WT).

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.

scholarly journals Femtosecond-Laser-Assisted Fabrication of Radiation-Resistant Fiber Bragg Grating Sensors

2022 ◽  
Vol 12 (2) ◽  
pp. 886
Author(s):  
Hun-Kook Choi ◽  
Young-Jun Jung ◽  
Bong-Ahn Yu ◽  
Jae-Hee Sung ◽  
Ik-Bu Sohn ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Fiber Bragg Grating ◽  
Optical Fibers ◽  
Coming Out ◽  
Single Mode ◽  
Femtosecond Laser Irradiation ◽  
Bragg Grating ◽  
Wavelength Shift ◽  
Radiation Resistant ◽  
Fbg Sensors

This paper demonstrates the fabrication of radiation-resistant fiber Bragg grating (FBG) sensors using infrared femtosecond laser irradiation. FBG sensors were written inside acrylate-coated fluorine-doped single-mode specialty optical fibers. We detected the Bragg resonance at 1542 nm. By controlling the irradiation conditions, we improved the signal strength coming out from the FBG sensors. A significant reduction in the Bragg wavelength shift was detected in the fabricated FBG sensors for a radiation dose up to 105 gray, indicating excellent radiation resistance capabilities. We also characterized the temperature sensitivity of the radiation-resistant FBG sensors and detected outstanding performance.

scholarly journals Study on the Optimal Groove Shape and Glue Material for Fiber Bragg Grating Measuring Bolts

Sensors ◽  
2018 ◽  
Vol 18 (6) ◽  
pp. 1799 ◽  
Author(s):  
Yiming Zhao ◽  
Nong Zhang ◽  
Guangyao Si ◽  
Xuehua Li
Keyword(s):  
Fiber Bragg Grating ◽  
Linear Regression Analysis ◽  
Tensile Load ◽  
Tensile Tests ◽  
Bragg Grating ◽  
Engineering Practice ◽  
Direct Tension ◽  
Groove Shape ◽  
Fbg Sensors ◽  
The Impact

Fiber Bragg grating (FBG) measuring bolts, as a useful tool to evaluate the behaviors of steel bolts in underground engineering, can be manufactured by gluing the FBG sensors inside the grooves, which are usually symmetrical cuts along the steel bolt rod. The selection of the cut shape and the glue types could perceivably affect the final supporting strength of the bolts. Unfortunately, the impact of cut shape and glue type on bolting strength is not yet clear. In this study, based on direct tension tests, full tensile load–displacement curves of rock bolts with different groove shapes were obtained and analyzed. The effects of groove shape on the bolt strength were discussed, and the stress redistribution in the cross-section of a rock bolt with different grooves was simulated using ANSYS. The results indicated that the trapezoidal groove is best for manufacturing the FBG bolt due to its low reduction of supporting strength. Four types of glues commonly used for the FBG sensors were assessed by conducting tensile tests on the mechanical testing and simulation system and the static and dynamic optical interrogators system. Using linear regression analysis, the relationship between the reflected wavelength of FBG sensors and tensile load was obtained. Practical recommendations for glue selection in engineering practice are also provided.

Improving the Fatigue Performance of Welded Tubular Connections via Flared and Thickened Pipe Ends

2021 ◽  
Author(s):  
Ghiath Guy Mansour
Keyword(s):  
Fatigue Life ◽  
Lower Cost ◽  
Fatigue Performance ◽  
Viable Alternative ◽  
Welding Time ◽  
Time Cost ◽  
Steel Catenary Risers ◽  
The Many ◽  
Espirito Santo

Abstract Fatigue is a primary challenge in the design of steel catenary risers (SCRs) and different measures and methods are utilized to mitigate it. Traditional upset ends and steel lazy wave risers (SLWRs) are such methods to mitigate fatigue. SLWRs were first used in 2009 on the Espirito Santo floating, production, storage, and offloading (FPSO) vessel of Shell Company's Parque das Conchas (BC-10) project offshore Brazil. SLWRs have been used increasingly since then and gained popularity especially in recent years. A novel patented tubular connection assembly referred to as Flared Thickened Ends (FTEs) improves the fatigue life of SCRs and welded connections in general. This novel assembly has many advantages. It overcomes the thickness limitation of welding traditional upset ends and reduces offshore welding time, cost, and risk. When FTEs are used in simple SCRs, they render simple SCRs a robustly viable alternative at significantly lower cost, shorter schedule, and with many additional advantages as compared to SLWRs. Of the many advantages, simple SCRs are more straightforward to configure, analyze, design, and install using varied installation methods and vessels. Simple SCRs use less materials and offer better long-term integrity, especially for insulated SCRs. In addition, they have a smaller footprint and are less prone to clashing than SLWRs.

scholarly journals Stress Monitoring on GFRP Anchors Based on Fiber Bragg Grating Sensors

Sensors ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 1507 ◽  
Author(s):  
Hai-Lei Kou ◽  
Wang Li ◽  
Wang-Chun Zhang ◽  
Yuan Zhou ◽  
Xiao-Long Zhou
Keyword(s):  
Fiber Bragg Grating ◽  
Field Test ◽  
Weight Ratio ◽  
Electromagnetic Properties ◽  
Bragg Grating ◽  
Shear Stresses ◽  
Stress Profile ◽  
Stress Monitoring ◽  
Axial Forces ◽  
Fbg Sensors

Glass fiber-reinforced polymer (GFRP) bolts have been widely used in some applications of grouted anchors because of the advantages of better resistance to corrosion, high strength-to-weight ratio, low electromagnetic properties, and so on. This study presents a field test to assess the feasibility of fiber Bragg grating (FBG) sensors in monitoring the stress profile of GFRP anchors during pulling test. Two GFRP anchors were fully instrumented with FBG sensors and then installed into the ground using a drilling and grouting method. To measure the stress profile along test anchors, seven bare FBG sensors were arranged in a single optical fiber and then embedded in the middle of GFRP bolts in the process of extrusion molding. The procedure for embedding bare FBG sensors into GFRP bolts is introduced first. Then, the axial forces and shear stresses that were calculated from the measurements of the FBG sensors are discussed. The field test results indicate that the embedded FBG technology was feasible to monitor the stress state of GFRP anchors during pulling.

Detection of missing fastener based on vibration mode analysis using fiber Bragg grating (FBG) sensors

2003 ◽  
Author(s):  
Akiyoshi Shimada ◽  
Kei Urabe ◽  
Yoshihiro Kikushima ◽  
Jun Takahashi ◽  
Kazuro Kageyama
Keyword(s):  
Fiber Bragg Grating ◽  
Vibration Mode ◽  
Mode Analysis ◽  
Bragg Grating ◽  
Fbg Sensors
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