Fiber Bragg Grating Based Sensors and Systems

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

Overview of sensors suitable for active flow control methods

Hlavným cieľom tejto bakalárskej práce bolo vytvorenie prehľadu vyvíjaných a už aplikovaných senzorov pre účely aktívneho riadenia prúdov. Senzory musia splňovať niektoré podmienky, preto výber senzorov bol naviazaný na reálnych výsledkoch testovacích programov, popis ktorých tvorí prvú časť tejto bakalárskej práce. Opis technológie a princíp fungovania senzorov je popísaný v druhej časti tejto práce.The main purpose of this bachelor thesis was to create the overview of the sensors developed for the future active flow control applications and overview the sensors already used in the active flow control applications. The sensors have to fulfil several requirements, so selection for the overview was based on the real flight test programs results, which were described in the first part of the thesis. The sensors technology description and operation principles were included in the second part of the thesis

Characterization and Modelling of Composites

Composites have increasingly been used in various structural components in the aerospace, marine, automotive, and wind energy sectors. The material characterization of composites is a vital part of the product development and production process. Physical, mechanical, and chemical characterization helps developers to further their understanding of products and materials, thus ensuring quality control. Achieving an in-depth understanding and consequent improvement of the general performance of these materials, however, still requires complex material modeling and simulation tools, which are often multiscale and encompass multiphysics. This Special Issue aims to solicit papers concerning promising, recent developments in composite modeling, simulation, and characterization, in both design and manufacturing areas, including experimental as well as industrial-scale case studies. All submitted manuscripts will undergo a rigorous review process and will only be considered for publication if they meet journal standards. Selected top articles may have their processing charges waived at the recommendation of reviewers and the Guest Editor

Fiber Optical Sensing of Bearing Performance and Pump Conditions

Lectur

Optical Distributed Sensing: Reel-To-Reel Fabrication of Quasi-Distributed FBGs for Improved Scattering Signal and Enhanced Harsh Environment Stability

Bragg gratings inscribed in optical fiber are key components for both multiplexable and distributed optical sensing. Comparing with other sensor devices, Bragg grating based fiber sensors offer a number of advantages include low manufacturing cost, immunity to electromagnetic fields (IMFs), long lifetimes, high sensitivity, multiplexing, and environmental ruggedness. Bragg grating based fiber sensor arrays have been used extensive to perform structural health monitoring for large civil and mechanic structures. To perform high spatial resolution measurements on large structures, thousands of grating devices need to be multiplexed on a single fiber. In this thesis, a fully automated reel-to-reel fiber handling system is designed and integrated into a KrF 248-nm excimer laser, enabling continuous Bragg grating fabrication using a phase mask approach. Through the control of fiber tension and spooling speed, grating sensor can be inscribed continuously at desired locations within 5-mm accuracy. One hundred fifty evenly spaced FBGs have been successfully inscribed in a single fiber with 3-cm spacing, spectral and spatial characteristics of these fiber sensors are characterized using an Optical Backscatter Reflectometry (OBR). The spectral accuracy was within 0.5-nm of the designed grating wavelength, which are sufficient for both optical time domain reflectometry and optical frequency domain reflectometry interrogation. The successful development of this fully automated grating fabrication system enable development of fiber sensing cables for a wide array of applications