Effect of Strain Or Stress Applied Using Fiber Bragg Grating Sensor with the Analysis of Apodization on the Performance of the Sensor
Effect of Strain Or Stress Applied Using Fiber Bragg Grating Sensor with the Analysis of Apodization on the Performance of the Sensor

Author: Shilpa Shankar

Publisher:

Published: 2015

Total Pages: 32

ISBN-13: 9781339292922

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Abstract: This project is aimed at designing and optimizing the performance of a Fiber Bragg Grating strain sensor using different apodization profiles. FBG sensors are based on the principle that the Bragg wavelength changes with the change in grating period, length, and reflectivity. Hence, any physical parameter like stress, strain, pressure and temperature that causes a shift in the Bragg wavelength can be measured using an FBG. Ideally to use an FBG in strain sensing applications, it should have high reflectivity, low sidelobe levels and narrow full-width half maximum (FWHM). Based on this theory, an investigation of different apodization profiles on evaluation parameters such as reflectivity, sidelobes, and FWHM is performed. Blackman profile is found to be the best apodization profile, which can be used in sensing applications with the maximum reflectivity of 99.43%, minimum sidelobe levels, and narrow FWHM.

Fiber Bragg Grating Based Sensors and Systems
Fiber Bragg Grating Based Sensors and Systems

Author: Oleg Morozov

Publisher: MDPI

Published: 2021-08-18

Total Pages: 228

ISBN-13: 3036512861

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This book is a collection of papers that originated as a Special Issue, focused on some recent advances related to fiber Bragg grating-based sensors and systems. Conventionally, this book can be divided into three parts: intelligent systems, new types of sensors, and original interrogators. The intelligent systems presented include evaluation of strain transition properties between cast-in FBGs and cast aluminum during uniaxial straining, multi-point strain measurements on a containment vessel, damage detection methods based on long-gauge FBG for highway bridges, evaluation of a coupled sequential approach for rotorcraft landing simulation, wearable hand modules and real-time tracking algorithms for measuring finger joint angles of different hand sizes, and glaze icing detection of 110 kV composite insulators. New types of sensors are reflected in multi-addressed fiber Bragg structures for microwave–photonic sensor systems, its applications in load-sensing wheel hub bearings, and more complex influence in problems of generation of vortex optical beams based on chiral fiber-optic periodic structures. Original interrogators include research in optical designs with curved detectors for FBG interrogation monitors; demonstration of a filterless, multi-point, and temperature-independent FBG dynamical demodulator using pulse-width modulation; and dual wavelength differential detection of FBG sensors with a pulsed DFB laser.

Strain Transfer Analysis of Embedded Fiber Bragg Grating Strain Sensor
Strain Transfer Analysis of Embedded Fiber Bragg Grating Strain Sensor

Author: Jun Li

Publisher:

Published: 2015

Total Pages: 9

ISBN-13:

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Due to the difference in the physical and mechanical properties between the optical fiber, protective layer, adhesive layer, and the host material, the strains measured by a fiber Bragg grating (FBG) sensor may not be the actual strains of the host material, which impedes the reliable applications of FBG sensors. To overcome this problem, in this paper, the strain transfer formula was derived by using elastic analysis, the shear-lag method, and several reasonable assumptions taking into account temperature variations and nonaxial stresses, which was an improvement to an existing study (Li, H. N., Zhou, G. D., Ren, L., and Li, D. S., "Strain Transfer Analysis of Embedded Fiber Bragg Grating Sensor Under Nonaxial Stress," Optic. Eng., Volume 46, No. 5, 2007, 054402). The analytical results were validated by simulating the behavior of a bare optical fiber through finite element analysis. The data enabled the identification of the parameters that influence the strain transfer from the host material to the embedded FBG sensors and the impact of the temperature variation and sensor alignment angle on the measurement accuracy. This work provided additional knowledge for the improvement of the existing strain transfer theory of FBG sensors in order to achieve a more accurate strain measurement with this sensing technology.

Fiber Bragg Grating Sensors
Fiber Bragg Grating Sensors

Author: Oleg G Morozov

Publisher:

Published: 2024-07-16

Total Pages: 0

ISBN-13: 9783725816408

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This reprint aims to explore one of the most popular trends of relevance to sensors, which represents an influential platform for the exchange of scientific knowledge in the field of FBGs from the point of view of its recent advances and future perspectives. We are opening small, but very interesting pages in FBGs' 35-year history. The first section is devoted to the modernization of FBG basics and its performance in various conditions: line-by-line inscription of tilted FBGs, radiation effects on FBGs, and short-term creep effect on strain transfer from fiber-reinforced polymer strips. The second one details new approaches to interrogation methods: a detailed algorithm of FBG spectrum distortion correction for classical OSA with CCD elements and noise analysis of new microwave photonic interrogation of fiber-based sensors. The next section reflects the results of using FBGs in aviation systems: noise cancellation of helicopter blade deformations, design of a high-precision shape sensor for wing shape reconstruction, and development of a medium-frequency accelerometer based on flexible hinges. We separately discuss the transfer of FBG technologies to new devices based on integral photonics and new mediums in which FBGs can gain new life: modeling a fully integrated micro-ring-based photonic system for liquid refractometry and designing wavelength-tunable vortex beam emitters based on silicon micro-rings and twisted few-mode optical fibers with improved height of quasi-step refractive index profiles.

Performance Evaluation of Fiber Bragg Grating Temperature Sensor
Performance Evaluation of Fiber Bragg Grating Temperature Sensor

Author: Taha Ali Alian

Publisher: LAP Lambert Academic Publishing

Published: 2014-08-11

Total Pages: 108

ISBN-13: 9783659585906

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In this work, different FBG temperature sensors are simulated and evaluated with various apodization profiles. A New apodization function is proposed with a remarkable performance compared even with the Gaussian profile. Also, and for the first time, we introduce the Nuttall apodization profile with detailed analysis. Evaluation is done under a wide range of controlling design parameters like sensor length and refractive index modulation amplitude, targeting a remarkable temperature sensing performance. New judgment techniques are introduced such as apodization window roll-off rate, asymptotic sidelobe decay level, number of sidelobes, average sidelobe level and channel isolation. Evaluation techniques like reflectivity, Full Width at Half Maximum (FWHM), and Sidelobe Suppression Ratio are also used. A study is performed on including an unapodized sensor among apodized sensors in a quasi-distributed sensing system. The obtained results demonstrated the importance of investigating the previous controlling parameters and consequently the precise control on the FBG temperature sensor various characteristics to get the optimum sensor performance according to the application needs.

Fiber Bragg Grating Sensors: Development and Applications
Fiber Bragg Grating Sensors: Development and Applications

Author: Hisham K. Hisham

Publisher: CRC Press

Published: 2019-06-19

Total Pages: 117

ISBN-13: 1000021726

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This book presents the basic principles of optical sensor technology in line with the tremendous development in the concept of optical fibers. In the first four chapters, the book discusses the basic principles of optical sensor technology in a simplified manner, making it suitable for all levels of study and research. The seven remaining chapters are concerned with the practical applications of optical sensor technology in all fields such as oil and gas, civil engineering, medical and military fields and harsh environments.

A Distributed Temperature Sensor Using Fiber Bragg Grating
A Distributed Temperature Sensor Using Fiber Bragg Grating

Author: Solomon Abebe Gugsa

Publisher:

Published: 2000

Total Pages: 214

ISBN-13:

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ABSTRACT: Fiber sensing technology has reached qualitatively new performances with the advent of fiber Bragg gratings. However a major problem using a fiber Bragg arises when the sensor is subject to a non-uniform temperature or strain along its length. Based on the existing signal processing schemes and sensor designs, only the average temperature or strain may be obtained. In this thesis a new technique is presented that enables us to obtain the complete temperature or strain profile along the sensing length. For this purpose, a phase discontinuity in the grating structure is introduced. This phase discontinuity breaks the symmetry of the grating profile in wavelength domain. In effect, in the reflection band of a Bragg grating we introduce a very narrow pass-band that under uniform temperature, results in the position of this window in the grating spectrum remaining unchanged. However, when a non-uniform strain or temperature is applied, the location of this wavelength window in the reflection spectrum will change. This would allow us to obtain the temperature or strain distribution along the sensor length. The signal processing used to experimentally demonstrate a distributed fiber sensor has been fully described elsewhere. A theoretical model was developed to obtain thermal distribution from the spectrum of the phase shifted Bragg grating. The theoretical model and analysis of this sensing mechanism will be discussed and experimental results will be presented in this thesis.

Apodized Fiber Bragg Grating Strain Sensor
Apodized Fiber Bragg Grating Strain Sensor

Author: Khurram Shahzad Khalid

Publisher: LAP Lambert Academic Publishing

Published: 2012-03

Total Pages: 68

ISBN-13: 9783848440665

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In this text book, the performance comparison of various Apodization profiles in terms of side lobe suppression is investigated.This research is aimed to develop the mathematical model of the Apodized Fiber Bragg Grating Scheme in order to suppress side lobes, while maintaining the reflectivity and narrow bandwidth. MATLAB codes are written to solve the coupled mode equations for the analysis of optimized reflection spectra under Fiber Bragg grating Strain Sensor.Finally the simulation results of MATLAB are compared with the results obtained by the standard software of Opti-grating version 4.2.

Theoretical and Experimental Analysis of Strain Transfer Rate in Coated Fiber Bragg Grating Strain Sensors
Theoretical and Experimental Analysis of Strain Transfer Rate in Coated Fiber Bragg Grating Strain Sensors

Author: Chakameh Dadpay

Publisher:

Published: 2008

Total Pages: 0

ISBN-13:

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Fiber Bragg Grating (FBG) sensors have seen significant development in recent years, especially in the aerospace industry for structural health monitoring due to their versatility and measurement capability. Improvement in sensor's reliability and accuracy, however, continue to be two parameters critical to the eventual implementation of this technology in high value targets and can be enhanced by the effect of both mechanical and optical characteristics of the fiber. This thesis presents an evaluation of the strain transfer capability of different coated FBG strain sensors (i.e. Gold, Polyamide and Acrylic) bonded to metallic host structures. A theoretical relationship for the strain transfer rate from the host structure to the fiber core has been developed. This relationship considers the strain transfer loss through the layers of the system based on their material properties and their geometry. In addition, a simulated analysis using finite element modeling has been developed. Parametric analysis of both the analytical and simulation models revealed the impact of coating material selection, coating thickness selection, and bonding condition on the strain transfer loss. Results illustrate that metallic fiber coatings (i.e. Gold) are more suitable for improved strain transfer than their polymeric counterparts. Additionally a set of experiments were conducted using Acrylic coated FBG sensor bonded to an Aluminium sample to validate the results from theory and the simulation. The strain on the FBG sensor was measured and compared with a calibrated strain gauge mounted on the host structure to characterize the strain transfer loss. The experimental results were compared with the results for the same configuration of the sensor and its host structure, from the theory and simulation and were found to be in good agreement.