RIBAM proposes the development of novel in-situ technologies for manufacturing complex aeronautic composite parts, by out of autoclave approaches, and join them with induction and adhesives processes.
The project is challenging because of the technologies involved, the aeronautic requirements imposed, and the involved materials and processes development level. The targeted component has been a leading edge structure, kept as a goal from the beginning of the project until the end. It is composed of the skin and the ribs, to be joined by induction welding process.
For the skin of the part, a high performance reinforced thermoplastic was selected, for its consolidation by Automated Fibre Placement with in situ consolidation. This first approach had to be dismissed due to the low TRL of the proposed technology. The final solution for panels and leading edge skin fabrication was oven consolidation.
Even when considering a conventional technology, the high curvature of the surface brought strong difficulties to deliver the part without defects. The material involved, and the processes investigated in this project present a medium level of industrialization for highly curved surfaces with aeronautic requirements.
On the other hand, ribs were obtained by the additive manufacturing technology proposed, after deep research on the material and an optimization of the process. A research field of investigation is now open for increase the TRL, including post-processes and support strategies during fabrication.
The main limitation related to the ribs came from the mechanical properties of the material proposed and the behavior against bird-strikes events. It does not reach the desirable performance and therefore, the use of the ribs for flying purposes was dismissed for primary structures. However, it can be considered for secondary or auxiliary structures. The manufacturing process was proved to be robust enough to manufacture full scale components through additive manufacturing, several parts with enough repeatability.
RIBAM project has allowed the investigation of the induction welding process for dissimilar composites, obtained by different manufacturing technologies. It can be concluded that, even when the joints present an acceptable performance (compared to co-curing processes), repeatability is still far from an industrialization step. The spot size of the welding area must be improved in terms of the affected zone and the control of its dimension.
As a conclusion, RIBAM has allowed to investigate, maturate and propose solutions at demonstrator level for the application of novel manufacturing and assembly technologies with the main goal of in-situ manufacture dissimilar thermoplastic materials, joint them in a quick and flexible way, avoiding mechanical joints, and apply the developments to complex geometries such a Leading Edge with high level of curvature.
Examples of dissmination activities are the publication by DMRC of a scientific paper entitled “Investigation of specific FDM process parameters to optimize the polymer discharge of carbon fibre reinforced PEEK", published in "Macromolecular Symposia”; and the participation of CATEC in the national conference of composites materials, hold on the 21-23 of June 2022 at Seville. CATEC shared the results obtained by the characterization of the material developed in RIBAM for additive manufacturing purposes.
