Evaluation of Fuzzy Fiber Sensors for Structural Health Monitoring

Abstract : As advanced fiber composites are utilized more frequently in primary structural applications, there is a key challenge to enhance the performance and reliability while reducing maintenance. As a consequence, there is tremendous scientific and technical interest in the development of techniques for monitoring the health of composite structures where real-time sensing can provide information on the state of chemistry and micro-structural damage. In this study, it has been established that carbon nanotubes grown on carbon or glass fiber (nicknamed fuzzy fibers) can be utilized as electrical networks by transforming the insulating glass fiver to very conductive one. The fuzzy fiber was inserted into traditional composites during layup operations and then used as in situ sensors for detecting changes during oxidation of advanced fiber composites. In order to gain an insight toward the oxidation rate and durability of polymer composites, the integration of electrical resistance measurements though fuzzy fiber ends was used as function time. Fuzzy fiber grids built into composites enables tracking of oxidation rates between oxidation occurring at the core and skin of the composites. Using spectroscopy techniques, we were able to depict the oxidation mechanism and oxidation rate. During the degradation process, first oxygen adsorption took place and then, as the oxidation phenomena progressed, pits and cracks developed that led into structural properties. We identified a parameter that may be utilized as a quantitative measure of oxidation rate.