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Lecture

Ultrasonic welding of titanium to polymer-composite tubular structures: process analysis, mechanical properties and microstructure

Wednesday (29.04.2020)
10:40 - 11:00 Room TR 4-5

Hybrid structures are important for the aeronautical industry as they have the potential to reduce aircraft weight and improve fuel efficiency. A new and promising technique for aircraft applications is continuous ultrasonic metal welding to realize tubular metal–fiber reinforced polymer (FRP) hybrids for hydraulic components. Tubular metal–FRP hybrids, produced by an advanced type of ultrasonic metal welding, are investigated for the first time as a potential substitute for metallic hydraulic tubes. The oscillating welding system moves around the tubular joining partners to generate a sealed orbital connection. High mechanical strength is required for a safe application in the 5000 psi hydraulic system of current aircraft concepts. Process parameters for tubular metal–FRP hybrid joining were evaluated considering the mechanical and technological properties, as well as the microstructure of the hybrid interfacial area. The entire joining area of tubular joining partners has to be in close contact before welding to assure a continuous joint. Hence, the titanium fitting is thermally shrinked onto the FRP tube. Titanium is a challenging upper joining partner due to its high yield strength, hardness and low thermal conductivity. The welding sonotrode has to resist wear as well as stress and temperature gradients, while oscillating with displacement amplitudes close to 50 µm without fatigue failure. Suitable sonotrodes were developed for continuous ultrasonic welding of titanium alloys, considering material selection and geometry. Based on these results, the orbital ultrasonic welding technology will be systematically prepared for prospective industrial use and a future application of ultrasonically welded tubular multi-material-components.

Speaker:
Moritz Liesegang
TU Kaiserslautern
Additional Authors:
  • Prof. Dr. Tilmann Beck
    TU Kaiserslautern
  • Prof. Dr. Frank Balle
    University of Freiburg