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

Sensors

Umesh Sampath²  Hyunjin Kim²  Dae-gil Kim²  Young-Chon Kim²  Minho Song¹ 

[1] Division of Electronics and Information Engineering, Chonbuk National University, Jeonju 561-756, Korea; E-mails

关键词: cure monitoring;    Fresnel reflectivity;    fiber Bragg grating;    distorted sensors;    Gaussian curve fitting;   

DOI  :  10.3390/s150818229

来源: mdpi

【 摘 要 】

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.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.