Abstract

Fibre reinforced polymers are important materials used in aviation due to their excellent specific properties enabling the reduction of fuel consumption. For example, carbon fibre reinforced epoxy resins are used in fuselage and wing structures. Glass fibre reinforced phenolic resins are mainly used for the interior panels due to their low weight and favourable fire properties. All these composite materials used in aviation have one thing in common: they are man-made. Renewable materials like bio-fibres and bio-resins are under investigation for a long time for composites but they did not made it into modern aircraft in high amounts yet. The project ECO-COMPASS under Horizon 2020 aims to bundle the knowledge of 17 partners from China and Europe to develop ecological improved composites for the use in aircraft interior and secondary structures [1]. Bio-based reinforcements, epoxy resin and sandwich cores are developed and improved for their application in aviation. Furthermore the use of recycled carbon fibres to increase the mechanical strength and multifunctional aspects of bio-composites are evaluated. In order to withstand the special stresses in aviation environment, protection technologies to mitigate the risks of fire, lightning and moisture uptake are under investigation. An adapted modelling and simulation will enable the optimization of the composite design. Electrical conductive composites for electromagnetic interference shielding and lightning strike protection are under investigation in ECOCOMPASS as well. The cooperation includes the exchange of knowledge and materials in order to optimize the development of ecological friendly composites.

Abstract

In this work, new biocomposites were manufactured and mechanically tested. A resin from natural resources (SuperSap®) was reinforced by a bidirectional flax and oak wood laminates.

Normalized tensile and three-point bending tests were performed and it was observed that the oak wood laminates in the outer layers give a great aesthetic finish and the tensile stiffness is also increased a 2% compared to the flax reinforced biocomposite. Regarding the results of three-point bending, the oak laminates in the core provide a greater flexure breaking strength, which is a 10% higher than the flax reinforced biocomposite. SEM micrographs show both the accuracy of the infusion process and the good adhesion of the different natural fibres and bioresin.

Finite Element simulations (FEM) were carried out at different pressures generated by three wind velocities (V_wind= 3, 8 and 11m/s). Both tension and deformation results show that the structural integrity of the biocomposite wind blades is not compromised. Finally, the real tests in the wind tunnel have validated the use of the developed biomaterials in manufacturing blades for small wind turbines.