| Summary: | 碩士 === 國立成功大學 === 機械工程學系碩博士班 === 91 === This research investigates the focusing acoustic wave transducers, which are made from PZT piezoelectric ceramic with non-uniform thickness, and their performance. The investigation covers theoretical simulation, fabrication, and experimental measurement.
The simulation is based on finite element method (FEM) and equivalent circuit model. The piezoelectric impedance analysis has been carried out with ANSYS FEM analysis and PSpice equivalent circuit simulation. The equivalent circuit model of piezoelectric material is based on A. Püttmer’s work (1997), which consists of two parts, namely acoustic part and electric part. Both parts can be substituted by transmission lines and capacitors. Using an improve model proposed by G. Lypacewics (2002), the characteristics of a piezoelectric ceramic with non-uniform thickness is studied. The uniform and non-uniform piezoelectric ceramic disks are fabricated and measured by an impedance analyzer. The acoustic wave transducers are fabricated by those ceramics. The transducers’ properties are investigated with an acoustic field scanning system. It shows that the bandwidth of the transducer is improved with non-uniform thickness and proper backing material.
The experimental and simulation results of this work pave a way for designing a focusing ultrasound transducer with non-uniform thickness PZT ceramics. With wider bandwidth and higher central frequency, such transducer can be very useful for future non-destructive evaluation (NDE).
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