Add-on part for connecting to a component by torsional ultrasonic welding

The invention relates to a method for welding an add-on part (1) to a component, in particular for a motor vehicle, using the in per se known torsional ultrasonic welding method having a sonotrode for transferring the vibrations generating the welding process to the add-on part (1) to be welded, wherein the add-on part (1) has a coupling flange for coupling the vibrations of the sonotrode and the add-on part (1) has coupling elements for coupling the vibrations induced by the sonotrode in the welding region (11) facing the weld interface area of the component, and the coupling elements thereby melt during the welding process and thus weld the add-on part (1) to the component. In order to increase the amount and duration of the melt during the welding process on the weld interface area, and thereby to achieve the required melt temperature and active duration for generating the required bond quality, the protrusions (12) extending substantially perpendicular to the weld interface area (11) and disposed such tha