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M. Schikorra, M. Schomäcker, T. Kloppenborg, E. Tekkaya, K. Weidenmann, E. Kerscher, D. Löhe:
In: APT07 - International conference on Applied Production Technology, 17.9.-19.9.2007, Bremen, Germany,Proceedings, pp.285-292, ISBN 978-3-933762-21-4
The production of aircraft space frame structures by continuous reinforced stringer profiles offers the potential to reduce the weight at a simultaneous increase of the safety and the functionality. This may lead to further advantages to the usage of metallic components especially considering the actual competition between metals and carbon fiber reinforced polymers as construction materials.
Embedding endless wires or wire ropes made of high strength steel or Al2O3-fibers in aluminum stringer profiles by a composite extrusion process offers the potential to increase profile’s strength and stiffness and can, furthermore, act as crack-stopper in case of failure such as fracture. Within the work a method to introduce the reinforcement during the extrusion process is presented and investigations on embedding steel wires in profiles made of different aluminum alloys such as AA2099 and AA6056 are shown. In addition to the advanced tool design the paper presents the process analysis of embedding and microstructural analysis of the extruded profile and the interface region of wire reinforcement and the base material. Furthermore, investigations on finite-element simulations have been carried out to study the material flow in the die and give the possibility of process analysis in the areas of high pressure and high temperature. It has been shown that production of reinforced profiles made of typical aircraft alloys is possible without any structural defects such as gaps in the interface area. Special care has to be taken to treat the occurring high stresses and high punch forces due to the alloys mechanical properties.
The work has been done within the scope of a project of the Collaborative Research Center SFB/TR 10 “Integration of forming, cutting, and joining for flexible production of light weight space frame structures” funded by the German Research Foundation (DFG). With participation of the Institute of Forming Technology and Lightweight Construction (IUL) of the University of Dortmund and the Institute of Material Sciences 1 (IWK1) of the Technical University of Karlsruhe the work is shared by the European Aeronautic Defence and Space Company (EADS), that provides the need for the profiles and characterization of the manufactured structures, Alcan, Alcoa, Alu Menziken and Aleris, that supply materials and extrusion process knowledge, and Sandvik Materials Technology and VAC Vacuumschmelze, that produce the high strength steel wires for reinforcement.