Cure Monitoring of Composite Carbon / Epoxy through Electrical Impedance Analysis
Composite materials are increasingly used in aeronautic; they offer many benefits such as mechanical strength, mass and consumption reduction. However, their process development needs to be known and controlled, in order to adjust the process parameters and optimize the characteristics of structures made from these materials. This paper is focused on impedance spectroscopy measurement and analysis technique to characterize material’s properties. In fact, the composites based on carbon fiber have electrical proprieties; therefore a three-dimensional modeling of the electrical conduction in the material is established by using a distributed allocation of an electrical resistance (RP) in parallel with a capacitance (CP). Then, thin electrodes (40 μm thick) are inserted inside the material and a specific impedance measurement bench is developed to perform real-time measurements of RP and CP on unidirectional (UD) mono-ply and multi-plies samples. During curing (in an oven) the change in values of both RP and CP in different stages of the curing cycle is showed. Then, problems that occur during the curing cycle (layup defect, loss of vacuum) were detected by a large gap of the measured electrical parameters in comparison with the ordinary case. Therefore, by this electrical measurement, we present a way to ensure an automated real-time monitoring of the composite curing
Electrical impedance spectroscopy for measuring the impedance response of carbon-fiber-reinforced polymer composite laminates
Abstract Techniques that monitor the change in the electrical properties of materials are promising for both non-destructive testing and structural health monitoring of carbon-fiber-reinforced polymers (CFRPs). However, achieving reliable monitoring using these techniques requires an in-depth understanding of the impedance response of these materials when subjected to an alternating electrical excitation, information that is only partially available in the literature. In this work, we investigate the electrical impedance spectroscopy response at various frequencies of laminates chosen to be representative of classical layups employed in composite structures. We clarify the relationship between the frequency of the electrical current, the conductivity of the surface ply and the probing depth for different CFRP configurations for more efficient electrical signal-based inspections. We also investigate the effect of the amplitude of the input signal.
Degradable polymers : principles and applications
1. Why Biodegradable Polymers? G. Scott. 2. An Overview of Biodegradable Polymers and Biodegradation of Polymers S.H. Huang. 3. Degradation and Stabilization of Carbon-Chain Polymers G. Scott. 4. Techniques and Methods of Polymer Degradation S. Karlsson, A.-C. Albertsson. 5. Biodegradation of Aliphatic Polyesters Suming Li, M. Vert. 6. Starch-Polymer Composites C. Bastioli. 7. Polymers from Renewable Sources E. Chiellini, et al. 8. Sustainable Poly(Hydroxyalkanoate) (PHA) Production G. Braunegg. 9. Polyhydroxyalkanoates: Properties and Modification for High Volume Application I. Chodak. 10. Biodegradable Polymers in Medicine E Piskin. 11. Environmentally Biodegradable Water-Soluble Polymers G. Swift. 12. Plastics and the Environment J. Guillet. 13. Degradable Hydrocarbon Polymers in Waste and Litter Control G. Scott, D.M. Wiles. Subject Index.