Process and structural health monitoring of composite structures with embedded fiber optic sensors and piezoelectric transducers
Date
2012-08-24
Authors
Keulen, Casey James
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Abstract
Advanced composite materials are becoming increasingly more valuable in a plethora of engineering applications due to properties such as tailorability, low specific strength and stiffness and resistance to fatigue and corrosion. Compared to more traditional metallic and ceramic materials, advanced composites such as carbon, aramid or glass reinforced plastic are relatively new and still require research to optimize their capabilities. Three areas that composites stand to benefit from improvement are processing, damage detection and life prediction. Fiber optic sensors and piezoelectric transducers show great potential for advances in these areas. This dissertation presents
the research performed on improving the efficiency of advanced composite materials through the use of embedded fiber optic sensors and surface mounted piezoelectric transducers.
Embedded fiber optic sensors are used to detect the presence of resin during the injection stage of resin transfer molding, monitor the degree of cure and predict the remaining useful life while in service. A sophisticated resin transfer molding apparatus was developed with the ability of embedding fiber optics into the composite and a glass viewing window so that resin flow sensors could be verified visually. A novel technique for embedding optical fiber into both 2- and 3-D structures was developed. A theoretical model to predict the remaining useful life was developed
and a systematic test program was conducted to verify this model.
A network of piezoelectric transducers was bonded to a composite panel in order
to develop a structural health monitoring algorithm capable of detecting and locating
damage in a composite structure. A network configuration was introduced that
allows for a modular expansion of the system to accommodate larger structures and
an algorithm based on damage progression history was developed to implement the
network.
The details and results of this research are contained in four manuscripts that are
included in Appendices A-D while the body of the dissertation provides background
information and a summary of the results.
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Keywords
composite materials, structural health monitoring, fiber bragg grating, resin transfer molding