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Lecture

WEB Global and local properties of ultrasonically welded metal/CFRP-joints

Wednesday (29.04.2020)
10:20 - 10:40 Room 2

The advancement of lightweight concepts for modern aircraft structures incorporates the use of a diverse range of materials. As the number of interfaces in these hybrid lightweight structures is rising , the joining process has a significant impact on the resulting structural weight. Innovative technologies are needed to exploit material-specific advantages more effectively and realise high-performance, highly functional and at the same time light and robust structures. Conventionally applied joining technologies, e.g. mechanical fastening like riveting , are not efficient enough due to their mechanical, physical and chemical properties , which results in long process times and reduced load-carrying capability due to severed fibers.

 

Ultrasonic metal welding is a promising joining technique to address these material-specific advantages. This technology permits a more efficient design of multi-material joints, offering superior mechanical properties while maintaining the material's lightweight potential. In comparison to established joining technologies of aerospace or automotive sector , ultrasonic welding convinces with process times of a few seconds, a high degree of automation and a broad spectrum of process parameters that can be recorded and analyzed for quality assurance purposes.

 

The combination of fiber-reinforced thermoplastics like polyether ether ketone (PEEK) with light metal sheets such as Aluminium wrought alloys (e.g. AA5024) in hybrid structures by fast joining processes enable high-strength joints and reduced process times simultaneously. However, the development of robust hybrid joints raises material-specific challenges, for instance with regard to discrepancies in the thermal and electrochemical properties. In order to avoid electrochemical corrosion, the fiber reinforced polymeric joining partner is equipped with an electrically insulating glass fiber surface ply.

 

Within the scope of a research project, in cooperation with AIRBUS and CTC GmbH and funded by the German Research Foundation (DFG) collected findings are transferred to generic aerospace components. Furthermore, suitable process parameters were determined for certain hybrid combinations and the joints were analyzed mechanically and microscopically on their local and global properties. These latest research results will be presented and discussed at the 4th EuroHybrid conference.

Speaker:
Florian Staab
University of Freiburg
Additional Authors:
  • Prof. Dr. Frank Balle
    University of Freiburg