HESTIA

The aim of the project is the material- and energy-efficient production of window frames for aircraft fuselages using a thermoplastic composite material made from recycled carbon fibers. The characteristic properties of staple fibers are used in a specific way to make optimal use of the mechanical properties of the window frame structure. The implementation of this innovative material offers great potential for reducing CO₂ emissions in the production of aircraft components, while improving material efficiency and lightweight construction quality.

The starting material for the window frames are staple fiber yarns consisting of polyaryletherketone (PAEK) filaments and recycled carbon fibers with a length of more than 50 mm. These are formed into tapes in a specially developed impregnation and stretching unit at IVW. The result is a consolidated rCF tape (recycled Carbon Fiber) that contains oriented, discontinuous reinforcing fibers. This morphology enables wave-free placement due to the sliding of the fibers,, even in the production of components with complex, curved geometries, such as a window frame. Alignment along the curved load paths maximizes structural efficiency. In the next step, the load-bearing structure can be functionalized through overmoulding, ensuring optimal transfer of external loads into the insert.. This not only enables improved load distribution, but also significantly increases the durability and reliability of the entire structure.

A finite element model (FEM) is used to determine the optimal fiber paths and force introduction geometries. The simulation results arecompared with experimental tests to validate this numerical data. For this purpose, prototypes of aircraft window frames are manufactured and extensively tested.