Ultrasonic metal welding (USMW) is a technique of welding small-area materials by means of high-frequency vibration friction welding. Despite its wide use, it is still hard to monitor the welding process, and optimise the strengths of the welds it produces. The objective of this work is to offer a simple and automated characterization of the state of the welding process over time. This would allow quality control of all welds in an industrial process.

Furthermore, the analysis of the model and the available data will provide a better understanding of the physical behaviour of the weld over time.

This study will focus specifically on the USMW of two copper parts, analysing different measurements made with laser Doppler vibrometers and a high-speed camera. First, whether the motion transfer process between the horn and the anvil fulfils the properties of linearity and time invariance (LTI system), and can therefore be described by a transfer function, is checked. Then, the different phases of the welding process can be studied. After this validation and analysis, with the data obtained from the measurements, the validity of a mechanical model will be studied by trying to fit it to the results of the measurements.