Study of 1-3-2 piezoelectric composite based on the bandgap characteristic of phononic crystals

To enhance the operational performance of the 1-3-2 piezoelectric composite, this study proposes utilizing the bandgap characteristics of phononic crystals to suppress its lateral vibrations, thereby achieving purer thickness vibrations. The 1-3-2 piezoelectric composite is treated as a three-dimensional phononic crystal, and the finite element method is employed to calculate its band structure, transmission properties, and vibration modes. By adjusting the lattice configuration, the bandgap range of the phononic crystal is modulated. Through comparative simulations, the influence of the bandgap characteristics on the performance of the 1-3-2 piezoelectric composite is analyzed. The results demonstrate that when the resonant frequency lies within the bandgap range, lateral vibrations are significantly suppressed, resulting in purer thickness vibrations. Compared to a square lattice structure whose resonant frequency falls outside the bandgap, the hexagonal lattice structure with a resonant frequency within the bandgap exhibits a 3.2-fold increase in operational bandwidth in the thickness mode, suppressed side lobes, and significantly improved energy concentration, leading to optimized overall performance. This study provides new theoretical insights and methodological support for the structural design and performance enhancement of 1-3-2 piezoelectric composites and piezoelectric ultrasonic transducers.