Minimizing the Excitation of Parasitic Modes of Vibration in Slender Power Ultrasonic Devices

The design of slender power ultrasonic devices can often be challenging due to the excitation of parasitic modes of vibration during operation. The excitation of these modes is known to manifest from behaviors such as modal coupling which if not controlled or designed out of the system can, under operational conditions, lead to poor device performance and device failure. However, a report published by the authors has indicted that the excitation of these modes of vibration could be minimized through device design, specifically careful location of the piezoceramic stack. This paper illustrates that it is possible, through piezoceramic stack position, to minimize modal coupling between a parasitic mode and the tuned longitudinal mode of vibration for slender ultrasonic devices.