Acoustic Radiation Characteristics of Piezoelectric Shells with Internal and External Axial Stepped-Thickness Configurations

Abstract Using stepped-thickness variations, this work aims at amplifying the strength of the focused acoustic field generated inside a hollow piezoelectric cylindrical tube transducer without increasing the driving power. This requires a full understanding of the vibration and acoustic radiation characteristics of various configurations of piezoelectric tube transducers with internal and external axial stepped-thickness variations. A uniform-thickness cylindrical shell is machined at specific regions to acquire a stepped-thickness cylindrical shell with thin-walled regions. The design procedure includes determining the location and number of these thin regions. ANSYS software is used to determine the frequencies and mode shapes of various configurations of these shells. However, stress concentration, as an important design consideration, is also scrutinized at the step regions to avoid exceeding the material fatigue limit. An optimum design configuration for the stepped-thickness transducer is identified. Stronger acoustic fields are obtained using geometrical variations without any increase in the driving power. The simulations are validated experimentally with reasonable agreement.