The correct workflow of MAYA project in order to clarify the different manufacturing technologies to compare, the distinct scales of the specimens, and the way to follow for reaching a final solution has been a key point from the beginning and has been updated and improved to fulfil the objectives of the project.
First, the most suitable thermoplastic materials for connecting elements to other structures, in order to emphasize the advantages of a fully thermoplastic fuselage and lining have been identified and selected, according to aeronautic standards and specifications. The selected materials were PEI and PC.
Next, the design of the bracket for Additive Manufacturing (AM) has been solved with the same design for AM (Fused Deposition Modeling (FDM)) and IM in order to compare the performances, keeping manufacturing viability for both processes. The design has been achieved through several approaches and iterations with generative design and topological optimization of joining system, evaluating boundary conditions and objectives.
An injection tool has been manufactured to inject the optimized design bracket. A smaller version of the panel skin able to be bent has been integrated in the injection tool to demonstrate the concept feasibility. Within the process flow, this back-injected skin is then to be integrated in the thermoforming tool with the honeycomb to reach its final state. The injection trials have been executed providing reliable fast-paced solution for large volumes of parts, but the cost of implementing such solution relies on expensive tooling and machine equipment.
On the other hand, the direct 3D printing trials on composites have been printed, being alternatives to these 3 points: no tool means any design is virtually possible, machine cost can be a fraction of injection presses, and the possibility to automatize fabrication on an existing surface opens new possibilities. An additional point concerns the digital warehouse where parts are not stored physically but as a digital file on a hard drive. The drawback, however, is the manufacturing speed that would remain longer than an injection moulding shot. The use of combined technologies or other additive manufacturing technologies (SLA, SLS or MJF) could be a solution for future implementation. These are the main exploitable results, from the impact indicators and innovation outputs of the project, the viability of direct 3D printing on composites as innovative manufacturing route.
All of that has been supported by testing activities including characterization of material properties at coupon level, testing of small-scale demonstrators of the bracket, and finally evaluate the influence of process upscaling on the part properties by testing large-scale parts. The TRL level progression has been as expected (TRL5), following Building-block approach (BBA), from level 1 to 3, coupons level (fracture specimens) to large-scale level (demonstrator), achieving a quantitative assessment of the final developed engineering solution. The test results for level 3 specimens were performed well in AM and IM and might be considered as the final solution for the manufacturing of brackets.
The MAYA project’s partners have been carried some dissemination activities with the participation in workshops, trade fairs and conferences.
