Process management of ultrasonic spot welding and mechanical as well as microstructural properties of Al/Steel-joints for automotive applications will be investigated in this research project. Major aims are a scientific comparison and the transfer of single to multi-spot hybrid joints. So the lab work shall be transferred on geometries which are close to components and realized by a robust solid state joining process.
Laser-doppler-vibrometry for detailed vibration analysis and accompanying simulations will be performed to ensure reproducible and stable process conditions. General damping concepts and design guidelines for ultrasonically weldable dissimilar joints will be developed. Additional studies aim for high quality of dissimilar joints regarding the influences of geometry and the frequency. Furthermore new concepts of multi-part sonotrodes based on hard and refractory metals will be studied. Welding force, vibration amplitude and welding energy as process-relevant parameters will be determined using an adapted design of experiments. Especially oscillation effects of multi-spot geometries as a function of the sequence, arrangement and joining partners will be investigated systematically.