Manufacture of continuous fiber-reinforced polymer composite structures with embedded optical fibers for on-line health monitoring via optical backscatter reflectometry

Abstract

Continuous fiber-reinforced polymer composites are widely used in high performance and high demanding structures because of their high strength and stiffness / weight ratios, as well as their versatility on manufacturing large size and complex geometry constructions. Typically, damage monitoring of in-service polymer matrix composite structures makes use of foil strain-gage sensors, so that full structural reliability evaluation is not guaranteed insofar as they are not able to detect flaw nucleation stage. Recently, a new structural health monitoring technology called Optical Backscatter Reflectometry has been proposed which utilizes the full length of embedded optical fibers as strain sensor to assess integrity status of composite structures. This is performed by correlating the spectral shift of the elastic Rayleigh or inelastic Raman backscatter signals inside the optical fibers with a particular state of structural damage (including its very onset) and temperature in the composite, thus allowing its remote, real-time, permanent health monitoring. This workplan proposal for the Research Internships Abroad Program (BEPE-FAPESP) describes the three main objectives to be pursued by the candidate during his 4 months stay in the Department of Engineering Design and Materials at the Norwegian University of Science and Technology (NTNU) in Norway, namely: (i) to manufacture flat and curved components of Continuous Fiber-Reinforced Polymer Composites with embedded optical fibers; (ii) to mechanically test the fabricated composite parts and simultaneously assess their integrity by means of the Optical Backscatter Reflectometry technique; (iii) to perform their complete post-mortem failure analysis. It is expected that the student be acquainted with the state-of-art in both the theoretical and experimental foundations of these quite important research, development and application fields, which still remain almost incipient in Brazil. (AU)