Highly integrated organic sheets for secondary structures in the aerospace industry

Motivation

The project developed a manufacturing process that integrates component development directly into the production of organic sheets. These organic sheets have variable thicknesses and are locally functionalised, and are based on hybrid non-woven fabrics containing recycled carbon fibres (rCF). The development of a two-stage thermoforming and joining process for these organic sheets, including a tailored tooling concept, enabled the series-production-ready manufacture of an aerospace demonstrator with near-final contours. The method enhances the cost-effectiveness and sustainability of organic sheet production.

Solution

The basis of the variable-thickness organic sheets is formed by rCF hybrid non-woven fabrics with a thermoplastic component and locally adapted structural and functional properties. These were manufactured on an intermittent hot press using a stepped mould with the following parameters:

• Implementation of thickness steps (2–4–6 mm) across the tool width, thickness tolerance ± 0.2 mm
• Integration of load-path-optimised reinforcement structures
• Suitable for series production (production speed 0.6 m/min; throughput up to 155.52 kg/h)

The further development of the two-stage thermoforming process with a corresponding tooling concept enabled the thermoforming and joining of the organic sheets into the box structure to final contour with process times of approx. 10 minutes using just a single modular mould.

The technical potential for series production on the project partners’ facilities was demonstrated. The integration of the joining processes with thermoforming offers economic advantages in terms of set-up times, tooling and energy requirements. Furthermore, prospects for the use of rCF-based components and the realisation of closed material cycles were highlighted.