ReFrame project commits to recyclable CFRP aircraft structure research

Fiber-reinforced plastics (FRPs) play a central role in modern aircraft construction, but material reuse in this field has been challenging. ReFrame aims to enable a closed carbon fiber recycling loop while maintaining the high-performance potential of carbon fibers. This is particularly paramount, as performance losses cannot be accepted for such high-performance components. Particular attention is to be paid to sandwich construction, which, at the end of service life, have not yet been able to be reused in equivalent structural components.

Through this project, partners will investigate, develop and implement the combination of CFRP sandwich structures with a core made of recycled raw material from thermoplastic cover layers. Since the cover layer and the core will be the same raw material, the entire structure will be able to be recycled and processed into a new core. 

The inter-university research network HP CFK (Leibniz University Hannover, TU Clausthal and TU Braunschweig) at the Stade site are covering the project’s entire development, from overall design and layout (TU Braunschweig) to material analysis and recycling (TU Clausthal) and production (Leibniz University Hannover). The cooperation is supported by PFH, Hansecampus Stade, which actively takes care of knowledge and technology transfer.

The Institute for Polymer Materials and Plastics Technology’s focus is on the recycling of thermoplastic fiber composite components and production-related waste, as well as their upgrade for reuse in high-performance applications. First, the recyclate will be processed into a short fiber-reinforced base compound, from which a pressable core material will be then produced through functionalization. In addition to 3D pressed core materials, the possibilities of printing individual short fiber-reinforced cores for use in sandwich structures are also being investigated.

The Chair of Aircraft Design at the Institute of Aircraft Design and Lightweight Construction will analyze possible areas of application and create an aircraft design that is tailored to the use of recycled structures and future mobility requirements. In addition, the Chair of Aircraft Design will design the structure using adapted methods for recycled materials, as these have a higher degree of variation in their material properties. The lightweight construction potential can be increased through targeted functional integration, for example by introducing fire hammers or sensors for structural monitoring. In order to enable complete and pure recycling of structures, the research project places a special focus on reversible joining methods.

IFW will investigate the potential use of recycled and bio-based materials in thermoplastic automated fiber placement (AFP) technologies to reduce primary raw materials in high-performance structures, thereby making a contribution to the implementation of sustainable mobility concepts. The use of AI-based process monitoring technology, digitalization approaches and energy-efficient manufacturing strategies lays the foundation for low-CO_₂ production.