A New 3-D Model of Composite Ultrasonic Transducer

A new 3-D model of a high-power composite ultrasonic transducer is proposed and evaluated in this article. This transducer comprises two active layers, each with at least two mechanically series-connected piezoelectric elements. A metal mass element is clamped between active layers with two bolts to create a sandwich structure comprising back and front metal radiation masses. The electromechanical equivalent circuit of the transducer, representing a general 1-D model, is first derived and presented in this article. The general 1-D model takes into account all existing transducer components, including both central bolts, in addition to the proposed 3-D model. In addition, when the effects of the bolts are excluded, the resonance frequency equation was analytically derived based on the general 1-D model. The composite transducer is designed and manufactured. For a large number of electrical connection combinations, transducer resonance frequencies are measured and compared with the results obtained from 3-D to 1-D models. The results indicate that the resonance frequencies obtained from the 1-D model are in line with the measured frequencies for the first thickness mode only. However, for all thickness and radial oscillation modes and their mutual coupling, the analytically obtained frequencies from the 3-D model correspond well to the measured frequencies. In addition, the presented results in this article contribute to a better understanding of the geometry and material properties of the composite piezoelectric transducer parts impact on transducer behavior.