Modal interaction in ultrasonic welding block sonotrodes induced by the mistuning of the material properties

In many ultrasonic applications, block sonotrodes are serially coupled with other tuned components to transmit the longitudinal vibration to the workpiece. Uniform vibration amplitude of the output surface is an important criterion for determining quality. It is known that amplitude uniformity is related to other non-tuned modes. In this paper, another type of modal interaction is used to quantify distortion of the first longitudinal mode, when the system exhibits a loss of symmetry (mistuning) and near natural frequencies.