Design, analysis, and manufacturing of a carbon-fibre-reinforced polyetheretherketone slat

Abstract

Composite structures are increasingly being used in aircraft applications. Regarding Airliners, the application of composites within impact endangered areas is unusual. In cooperation with DLR - Institute of Structures and Design and EADS - Innovation Works, an advanced thermoplastic composite slat, based on an aluminum A340-600 outer slat, had been developed with the aim of minimizing weight and manufacturing costs in series production. The investigation of many manufacturing techniques had been performed as well as integration of new materials. Several generic and full scale thermoplastic demonstrators were manufactured, using endless fiber reinforced CF-PEEK. The critical point, concerning the casting of thick and highly tapered, single curved thermoplastic shells, was identified and new manufacturing methods had been developed. Additionally, the thermoplastic welding process was improved, resulting in a low cost assembly technique as alternative to state-of-the-art joining methods such as riveting. In addition to conventional linear static analysis, dynamic high velocity impact simulations were carried out. A numerical approach for high velocity bird strike impact had been developed. The results were used to dimension the residual strength of a damaged slat. Furthermore, a good compliance between the dynamic analysis and the performed tests has been reached. It has been shown, that a significant weight reduction is possible by numerical optimization, even if brittle materials as composites are used for impact sensitive areas. The verification of the impact performance for high performance thermoplastic materials had been demonstrated as well as the possibility of manufacturing skins of complex geometry, using out-of-autoclave manufacturing methods. Existent welding methods had been adapted to usage with endless carbon fiber reinforced CF-PEEK.