ZEUS – Integral thermoplastic architectures and processes

Due to their remarkable weight-related properties, fiber-reinforced composites have become indispensable in aviation. As the proportion of fiber-reinforced components increases, the aspects of reparability and recycling of end-of-life components are also receiving increasing attention. Advancements in these areas can be achieved primarily by using thermoplastic composites, which can be remelted and reused without significant loss of quality. The LuFo project ZEUS is therefore researching the use of fiber-reinforced high-performance thermoplastics for complex, structural aircraft components. Using an integral door environment, load paths and manufacturing possibilities are to be optimally utilized in order to overcome existing restrictions, such as the frame position in the aircraft fuselage. In addition, the application of thermoplastics offers the possibility of forming flat semi-finished products in a single step and simultaneously joining them to prefabricated components (co-consolidation). The process chain is supplemented by overmolding with fiber-reinforced injection molding granulate, which can be used to compensate for tolerances, to fill structural gaps to minimize load peaks and to improve surface quality. In addition, stiffening elements such as ribs can also be produced in the same process step, greatly increasing the geometric complexity of the components. Such a door environment can then be connected to the aircraft skin by welding, making structurally weakening joining processes such as riveting, which is established in aircraft construction, superfluous. The use of extensive process simulation largely eliminates the need for costly and material-intensive preliminary tests, which also helps to preserve resources.

Automated manufacturing processes supported by digital modeling are used to increase economic efficiency. The process begins with the tape laying of flat, near-net-shape preforms, whereby a laydown speed of over 1 m/s is aimed for. These are then melted in an infrared radiator field, automatically transferred to the press and formed there. Co-consolidation is carried out with prefabricated load introduction elements. Measurement data on the material and machines are recorded in all process steps, from which a digital twin can be created. The digital twin can be used for quality assurance and prediction.

The project “LuFo-ZEUS – Zero Emission Aircraft with Sustainable Fuselage Concept and Technology” is funded by the Federal Ministry for Economic Affairs and Climate Action on the basis of a decision by the German Bundestag (funding reference 20W2106F).