Prototype Manufacturing of Extruded Aluminum Aircraft Stringer Profiles with Continuous Reinforcement

Abstract

Abstract. For an increase in safety against crack initiation and growth in metallic structures of airplanes different concepts were developed in the past. In the focus of this work are profiles made of continuously reinforced extruded aluminum. The production and the used die set of these profiles is presented as well as problems occurring in terms of geometrical inaccuracies of the embedded high strength wires. In addition, this paper attends to the problem of lateral seam weld formation. The interface between the AA-2099 as well as AA-6056 aluminum alloy and the high strength wires Nivaflex and Nanoflex were characterized by metallurgic investigations and push-out tests. As a result it can be stated that a sufficient geometrical accuracy could be achieved and a high interface strength can be accomplished even if a slight gap is still present in the interface layer between matrix and reinforcing element.

Mechanical Properties of Compound Extruded Aircraft Stringer Profiles Under Cyclic Loading

“…Up to now, research results on the extrusion of the medium and high strength aluminium alloys EN AW-6065 and EN AW-2099 showed that a stable process and a good embedding of the reinforcing elements can be achieved and that the mechanical properties under quasi-static loading conditions are increased significantly by the reinforcements as well. [5,6] However, the question if it is possible to increase the resistance against crack growth and crack propagation using these material combinations remained unanswered. Furthermore the influence of the process chain (solution annealing, quenching, stretch forming and artificial aging) on the interface between the aluminium and the wire has to be investigated.…”