STRAIN MEASUREMENT AT CANTILEVER BEAM WITH FIBER BRAGG GRATING SENSORS AND COLLIMATORS AND ITS CORRECTION METHOD

2012 ◽  
Vol 06 ◽  
pp. 576-582
Author(s):  
Seung Min Tak ◽  
Min Kyu Kang ◽  
Dong Jin Park ◽  
Seok Soon Lee
Keyword(s):  
Optical Fiber ◽  
Fiber Bragg Grating ◽  
Cantilever Beam ◽  
Strain Measurement ◽  
Wave Length ◽  
Correction Method ◽  
The Other ◽  
Bragg Grating ◽  
Fiber Bragg Grating Sensors ◽  
Fbg Sensors

Recently, Fiber Bragg Grating(FBG) sensors are being used in various fields. However, it has difficulty to measure at the place where it is not possible to connect fibers each other physically. In this study, using FBG a collimator, we have measured strains with a single optical fiber with many FBG sensors where FBG sensors on one optical fiber line is installed on the beam and the other optical fiber line is connected with an optical interrogator installed at stationary side. The optical fiber lines between an optical fiber line with FBG sensors on the beam and the other optical fiber line on the stationary part are connected by the collimator which makes the use of light's unique characteristic - light travels through space. The experiment showed that the wave length of the light were changed to be linear as strains increased, and the accurate strains were measured by applying the collimator collection factor, which was proposed in this paper.

scholarly journals New Method of Temperature and Strain Decoupling Based on Directivity of Fiber Bragg Grating Sensing

2021 ◽  
Vol 2101 (1) ◽  
pp. 012023
Author(s):  
Xiao Huang ◽  
Zhenkun Jin ◽  
Qing Shen
Keyword(s):  
Fiber Bragg Grating ◽  
Cantilever Beam ◽  
Experimental Analysis ◽  
Strain Measurement ◽  
The Other ◽  
New Method ◽  
Bragg Grating ◽  
Center Wavelength ◽  
Influence Of Temperature ◽  
Sensing Characteristics

Abstract Fiber Bragg Grating (FBG) has been widely used in temperature and strain measurement. Its center wavelength drift is affected by both temperature and strain. The influence of temperature and strain on center wavelength should be decoupled when measuring. In this paper, the sensing characteristics of FBG which pasted at different angles were simulated and analyzed, and it was found that FBG sensing for strain has strong directivity. A dual FBG composite construction based on the directivity of FBG sensing was proposed. Two FBGs were at an Angle of 62°. One FBG was sensitive to both temperature and strain, and the other was only sensitive to temperature. The structure can realize the decoupling of temperature and strain, and it doesn’t depend on feature of cantilever beam. It was verified by experimental analysis that the decoupling result was good by utilizing the combined FBG structure, and decoupling was realized easily.

Experimental Mode Shape Identification for a Cantilever Beam Using Optical Fiber Bragg Gratings

2017 ◽  
Author(s):  
Patrick S. Heaney ◽  
Onur Bilgen
Keyword(s):  
Optical Fiber ◽  
Fiber Bragg Grating ◽  
Cantilever Beam ◽  
Mode Shape ◽  
Distributed Parameter ◽  
Bragg Grating ◽  
Single Degree Of Freedom ◽  
Fiber Bragg Grating Sensors ◽  
Single Degree ◽  
Distributed Parameter Model

Parameter estimation of a cantilever beam model typically involves estimating the effective parameters of the system for an assumed mode shape. This shape assumption, which is difficult to verify with traditional single-point sensors, can be validated through the distributed strain measurements available from optical Fiber Bragg Grating sensors. In this paper, the experimental mode shapes of a cantilever beam acquired from Fiber Bragg Grating sensors are compared with the analytical predictions of classical beam theory for the first two bending modes. A single degree of freedom model is also analyzed for the first bending mode and compared to the distributed parameter model and experimental data. It is shown that the distributed parameter model provides a good estimate of the strain profile at the first two natural frequencies, and that the single degree of freedom and distributed parameter models are in close agreement at the first natural frequency.

scholarly journals Load Identification for a Cantilever Beam Based on Fiber Bragg Grating Sensors

Sensors ◽  
2017 ◽  
Vol 17 (8) ◽  
pp. 1733 ◽  
Author(s):  
Xuegang Song ◽  
Yuexin Zhang ◽  
Dakai Liang
Keyword(s):  
Fiber Bragg Grating ◽  
Cantilever Beam ◽  
Bragg Grating ◽  
Load Identification ◽  
Fiber Bragg Grating Sensors

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 Insole optical fiber Bragg grating sensors network for dynamic vertical force monitoring

2017 ◽  
Vol 22 (9) ◽  
pp. 091507 ◽  
Author(s):  
Maria Fátima Domingues ◽  
Cátia Tavares ◽  
Cátia Leitão ◽  
Anselmo Frizera-Neto ◽  
Nélia Alberto ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Fiber Bragg Grating ◽  
Bragg Grating ◽  
Vertical Force ◽  
Fiber Bragg Grating Sensors ◽  
Force Monitoring ◽  
Optical Fiber Bragg Grating

A smart insole for monitoring plantar pressure based on the fiber Bragg grating sensing technique

2019 ◽  
Vol 89 (17) ◽  
pp. 3433-3446 ◽  
Author(s):  
Rafique Ahmed Lakho ◽  
Zhang Yi-Fan ◽  
Jiang Jin-Hua ◽  
Hong Cheng-Yu ◽  
Zamir Ahmed Abro
Keyword(s):  
Optical Fiber ◽  
Pressure Distribution ◽  
Fiber Bragg Grating ◽  
Plantar Pressure ◽  
Bragg Grating ◽  
Body Postures ◽  
Plantar Pressure Distribution ◽  
The Subject ◽  
Fbg Sensors ◽  
Smart Insole

The analysis of plantar pressure distribution is essential in the field of biomedical and sports-related applications. In this study, a smart insole was developed for the measurement of plantar pressure distribution and the evaluation of body postures using optical fiber Bragg grating (FBG) sensing technology. Four FBG sensors characterized by four different center Bragg wavelengths, 1528 ± 0.3, 1532 ± 0.3, 1535 ± 0.3 and 1539 ± 0.3 nm, were located at the first metatarsus, third metatarsus, fifth metatarsus and heel position, respectively. The measurement sensitivity of all the FBG sensors was 0.000412 nm/kPa, approximately. Silica gel material of modulus = 10 MPa was selected to incorporate the FBG sensors. All FBG sensors were multiplexed together with one optical fiber cable. The performance and functional properties of all FBG-based pressure sensors were calibrated in the laboratory to evaluate plantar pressure distribution. A male subject was selected for performing four tasks, namely standing in an upright position, leaning forward, squat position and forward fold. During standing tests, plantar pressure observed at the heel position was around 57% higher than that at the first and third metatarsus, while the pressure of the fifth metatarsus position presents minimal pressure, which is only 37% that of the pressure of the heel position. When the subject performs leaning forward, the squat position and forward fold posture, the first and third metatarsi show maximum pressure, while the pressure decreases at the fifth metatarsus position. However, almost zero pressure is observed at the heel position when the subject changes the body postures of leaning forward, squat and forward fold posture. The extreme pressure of the forward fold posture was 1750 kPa acquired at the first metatarsus, which is 52% and 62% higher than those at the fifth and third metatarsi, respectively. Therefore, the smart insole successfully recorded both plantar pressure distribution and body posture changes regarding the wavelength values collected by the FBG sensors.

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