Development of an Equivalent Circuit to Analyze the Receiving Characteristics of a Class IV Flextensional Transducer

Flextensional transducers are widely utilized as underwater acoustic transducers with broadband and high-sensitivity characteristics in low-frequency ranges. In this study, we have developed an equivalent circuit to facilitate the design of a class IV flextensional hydrophone. The end-plate of the class IV transducer is essential for sustaining the structure while keeping the hydrophone waterproof in underwater environments, and the presence or absence of the end-plate changes the hydrophone's receiving performance. Previous studies have not included the end-plate in their equivalent circuit configurations, but this study proposes a new equivalent circuit model that incorporates an elastic boundary condition representing the constraint imposed on the shell by the compressive force of the end-plate. The receiving voltage sensitivity, calculated using the proposed equivalent circuit model, shows a high degree of agreement with the finite element analysis results, confirming that the mechanical influence of the end-plate significantly affects the hydrophone's acoustic receiver characteristics. The proposed equivalent circuit approach offers faster computation while maintaining sufficient accuracy compared to the finite element analysis, making it a useful tool for future hydrophone design.