In-Situ Cure Monitoring of Wind Turbine Blades by Using Fiber Bragg Grating Sensors and Fresnel Reflection Measurement

A fiber-optic cure monitoring system is proposed to measure curing status of composite structure such as a large scale wind turbine blade. The monitoring is based on the measurement of Fresnel reflectivity at the optical fiber/epoxy resin interface. The refractive index of epoxy resin varies through...

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Main Authors:	Umesh Sampath, Hyunjin Kim, Dae-gil Kim, Young-Chon Kim, Minho Song
Format:	Article
Language:	English
Published:	MDPI AG 2015-07-01
Series:	Sensors
Subjects:	cure monitoring Fresnel reflectivity fiber Bragg grating distorted sensors Gaussian curve fitting
Online Access:	http://www.mdpi.com/1424-8220/15/8/18229

id	doaj-8be23c80178f4d1ca616dfcc2b46ab70
record_format	Article
spelling	doaj-8be23c80178f4d1ca616dfcc2b46ab702020-11-24T21:43:25ZengMDPI AGSensors1424-82202015-07-01158182291823810.3390/s150818229s150818229In-Situ Cure Monitoring of Wind Turbine Blades by Using Fiber Bragg Grating Sensors and Fresnel Reflection MeasurementUmesh Sampath0Hyunjin Kim1Dae-gil Kim2Young-Chon Kim3Minho Song4Division of Electronics and Information Engineering, Chonbuk National University, Jeonju 561-756, KoreaDivision of Electronics and Information Engineering, Chonbuk National University, Jeonju 561-756, KoreaDivision of Electronics and Information Engineering, Chonbuk National University, Jeonju 561-756, KoreaDivision of Electronics and Information Engineering, Chonbuk National University, Jeonju 561-756, KoreaDivision of Electronics and Information Engineering, Chonbuk National University, Jeonju 561-756, KoreaA fiber-optic cure monitoring system is proposed to measure curing status of composite structure such as a large scale wind turbine blade. The monitoring is based on the measurement of Fresnel reflectivity at the optical fiber/epoxy resin interface. The refractive index of epoxy resin varies throughout curing stages, changing the Fresnel reflectivity. The curing status is decided by monitoring the reflected intensity variation. The usage of fiber Bragg grating (FBG) sensor helps to separate the temperature-induced cross effects. A Gaussian curve fitting algorithm was applied to FBG spectra which were distorted in curing procedure. The substantial measurement errors could be minimized by locating the centroids of the Gaussian curve-fitted spectra. From the experiments performed in various isothermal conditions, the proposed system successfully identified the onset of gelation and the completion of curing of epoxy resins.http://www.mdpi.com/1424-8220/15/8/18229cure monitoringFresnel reflectivityfiber Bragg gratingdistorted sensorsGaussian curve fitting
collection	DOAJ
language	English
format	Article
sources	DOAJ
author	Umesh Sampath Hyunjin Kim Dae-gil Kim Young-Chon Kim Minho Song
spellingShingle	Umesh Sampath Hyunjin Kim Dae-gil Kim Young-Chon Kim Minho Song In-Situ Cure Monitoring of Wind Turbine Blades by Using Fiber Bragg Grating Sensors and Fresnel Reflection Measurement Sensors cure monitoring Fresnel reflectivity fiber Bragg grating distorted sensors Gaussian curve fitting
author_facet	Umesh Sampath Hyunjin Kim Dae-gil Kim Young-Chon Kim Minho Song
author_sort	Umesh Sampath
title	In-Situ Cure Monitoring of Wind Turbine Blades by Using Fiber Bragg Grating Sensors and Fresnel Reflection Measurement
title_short	In-Situ Cure Monitoring of Wind Turbine Blades by Using Fiber Bragg Grating Sensors and Fresnel Reflection Measurement
title_full	In-Situ Cure Monitoring of Wind Turbine Blades by Using Fiber Bragg Grating Sensors and Fresnel Reflection Measurement
title_fullStr	In-Situ Cure Monitoring of Wind Turbine Blades by Using Fiber Bragg Grating Sensors and Fresnel Reflection Measurement
title_full_unstemmed	In-Situ Cure Monitoring of Wind Turbine Blades by Using Fiber Bragg Grating Sensors and Fresnel Reflection Measurement
title_sort	in-situ cure monitoring of wind turbine blades by using fiber bragg grating sensors and fresnel reflection measurement
publisher	MDPI AG
series	Sensors
issn	1424-8220
publishDate	2015-07-01
description	A fiber-optic cure monitoring system is proposed to measure curing status of composite structure such as a large scale wind turbine blade. The monitoring is based on the measurement of Fresnel reflectivity at the optical fiber/epoxy resin interface. The refractive index of epoxy resin varies throughout curing stages, changing the Fresnel reflectivity. The curing status is decided by monitoring the reflected intensity variation. The usage of fiber Bragg grating (FBG) sensor helps to separate the temperature-induced cross effects. A Gaussian curve fitting algorithm was applied to FBG spectra which were distorted in curing procedure. The substantial measurement errors could be minimized by locating the centroids of the Gaussian curve-fitted spectra. From the experiments performed in various isothermal conditions, the proposed system successfully identified the onset of gelation and the completion of curing of epoxy resins.
topic	cure monitoring Fresnel reflectivity fiber Bragg grating distorted sensors Gaussian curve fitting
url	http://www.mdpi.com/1424-8220/15/8/18229
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In-Situ Cure Monitoring of Wind Turbine Blades by Using Fiber Bragg Grating Sensors and Fresnel Reflection Measurement

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