Modal interactions in ultrasonic plate transducers for industrial applications

Among the green technologies that are currently investigated in industry, power ultrasound constitutes an emerging one with a good potential to produce and/or enhance a variety of processes. Lately, a series of power ultrasound systems for applications in the food industry, environment and manufacturing have been developed at laboratory and semi-industrial scales. In order to scale up these systems and their associated processes, elimination and/or control of detrimental modal couplings between tuned and undesired modes are necessary. In this study, the vibration behaviour of a tuned system for defoaming made up of a sandwich transducer of the Langevin-type driving an amplitude concentrator attached to a circular radiating plate was experimentally investigated. A three-mode interaction affecting the performance of the studied power ultrasound system was detected, characterized and classified. The information gathered through this study may be useful for the development of more efficient ultrasonic devices and processes.