CONNECTION DESIGN OF MULTIFUNCIONAL ELEMENTS IN THE PRIMARY STRUCTURE

Sustainability issues are playing an increasingly important role for future regional aircraft. As part of the EU-funded "Clean Aviation" framework, the HERWINGT project is developing lightweight construction methods to save fuel and thus reduce CO2 emissions. One approach is for future aerospace structures will be the integration of functions in addition to their actual structural function. For example, attached hollow stringers can be used as pipelines or feedthroughs for electrical or hydraulic media. The design of the stringer and the connection between the parts are an important role here. In close cooperation with Airbus Defense & Space GmbH, the integration of fuel vents in the omega stringer in the wing is being investigated. The manufacturing process is important, as the connecting elements often different in their various arrangements and can therefore vary very often. For this purpose, the 3D printing technologies is chosen to have a maximum in design freedom. For aerospace application high-temperature materials and media resistance materials like PEEK and PPSU are investigated. A filament printer (Fused Filament Fabrication = FFF) and a robot-based granulate printer (Fused Granular Fabrication = FGF) were used for validating the manufacturing process. The key technology bricks for the connectors are the tightness under pressure and media resistance. Therefore, a test stand for tightness was set up and mechanical test under kerosene environment were carry out.
It was shown, that the long-term influence of kerosene didn’t affect the tightness of PEEK and PPSU, nevertheless the mechanical behavior of PPSU was affected slightly by kerosene.