Controlling the effects of modal interactions in ultrasonic cutting devices

Modal interactions, and particularly combination resonances, are characteristic of ultrasonic devices driven at high power in a longitudinal mode. Such behaviour has been modelled previously parametrically excited simple structures such beams and bars, and it is possible to demonstrate that ultrasonic devices can exhibit dynamic responses that are qualitatively similar to theoretical models autoparametric systems. In this study, modal interactions are measured, and the benefits designing systems with a reduced number of modes are demonstrated.