Further development of an automated process for applying thermoplastic material onto fiber reinforced thermoplastics as preand postprocessing of joints (Masterarbeit)

Abstract

This master thesis discusses the further development of an automated process for applying thermoplastic material onto fiber reinforced thermoplastics as a pre- and postprocessing of joints using the prototype of the WeldSealer at the German Aerospace Center (DLR). The WeldSealer is a robotic-arm-based tool which can apply thermoplastic material to continuous fiber reinforced thermoplastics and can be used for many applications. This final paper examines in more detail the application of the energy director for ultrasonic welding as well as the sealing of welds by using the WeldSealer. The application of the energy director aims to reduce manual preprocessing and improve repeatability and is realized for the first time in this thesis. Sealing of welds is expected to increase the load bearing capacity and reduce the tolerance of the possible load bearing capacity. To further investigate these applications, test specimens were produced by resistance and ultrasonic welding. A subset was sealed, and then all samples were mechanically and visually tested. The results show that ultrasonic welding with an energy director applied by the WeldSealer is generally possible, but needs further optimization. It is found that sealing the welds can improve the load bearing capacity, as shown most notably with proven welding processes.