Periodic Reporting for period 2 - ECO-COMPASS (Ecological and Multifunctional Composites for Application in Aircraft Interior and Secondary Structures)
Reporting period: 2017-10-01 to 2019-06-30
Natural fibres flax and ramie were used for different types of reinforcements like fabric and nonwoven. Honeycomb sandwich cores with wood fibres substituting a part of the aramid fibres were successfully tested. Substitution of bisphenol-A based epoxy resins in secondary structures by partly bio-based epoxy resins was investigated with promising results. Material protection technologies were studied to reduce environmental influence and improve fire resistance. Modelling and simulation of chosen eco-composites optimised the use of materials while the Life Cycle Assessment aimed to investigate the ecological advantages compared to synthetic state-of-the-art materials.
Based on the current results with the materials considered in ECO-COMPASS, partly bio-based epoxy resin systems have the highest potential for a successful application in aviation. Their properties approach the performance of the fully petrol-based epoxy resins used today. Another promising group of thermoset bio-based resin, furan, has not been considered in ECO-COMPASS, but needs to be mentioned here for the very good fire properties comparable to classic phenolic resins. As a conclusion, thermoset bio-based resins show high potential to be applicable in aircraft secondary structure (epoxy) and interior (furan).
Natural fibres such as ramie, flax and sisal have a high potential for weight reduction due to their low density and good damping properties. However, their long-term behaviour (ageing) and mechanical properties need to be further improved. Potential technologies are under development, e.g. CNC coating, plasma treatment and hybridization with rCF. Fire properties are still an obstacle for the use of natural fibres in the interior. While flammability and toxicity are already under control, the heat release and smoke density properties need further improvement. On the other hand, the Green Honeycomb (GHC) with small amount of natural fibre mixed with classic aramid fibre can be another technology with high potential for the introduction of bio-based materials in aviation composite structures. Its long-term stability (humidity, etc.) needs to be validated in further tests. Nevertheless, the GHC may be used for secondary and interior structures because of its good fire and mechanical properties.
Moreover, the project enabled a unique leverage of resources, reinforced a long-term relationship of China and Europe in aeronautics and allowed mitigation of risks in the eco-composites development and production. The project results are of mutual benefit in several areas such as technology and knowledge transfer, exchanges and evaluation of developed materials and adoption of modelling and simulation tools with specific application for biomaterials with their divergent and more complex characteristics compared to manmade filaments like carbon and glass fibres in composites.
ECO -COMPASS has contributed to achieve the EU environmental goals set in FlightPath 2050 by demonstrating that some aircraft components can include new, eco-efficient and competitive materials.