Ring piezoelectric transducers (rPETs) have attracted multitudinous attentions due to their widespread applications in hydro-acoustic engineering, structural health monitoring, and energy harvesting. However, cracks are inevitably occurred by the concentrated stress at the interface between metal and piezoelectric ceramics, which will seriously affect the performance and service life of the devices. Hence, a novel functionally graded ring piezoelectric transducer (FG-rPET) has been designed and an accurate analytical system is constructed mainly including a three-port electromechanical equivalent circuit model (EECM) which can acquire exact solutions in radial vibration. In addition, the proposed three-port EECM has excellent generalizability, which is also applicable to conventional rPETs. The validity of the EECM is verified by experiments and the finite element method. The vibration characteristics (resonance/anti-resonance frequencies and effective electromechanical coupling coefficient (k_eff)) with fundamental and second modes for the FG-rPETs can be regulated via the inhomogeneity index and wall thickness. Markedly enhanced k_eff at second modes can be obtained for the FG-rPETs with specific wall thicknesses. The proposed analytical system has important guiding significance for structure optimization design of piezoelectric devices, and the designed FG-rPET is expected to break the bottleneck of mechanical properties for the conventional rPETs.

环形压电换能器（rPETs）因其在水声工程、结构健康监测和能量收集中的广泛应用而引起了广泛关注。然而，金属与压电陶瓷界面处应力集中，不可避免地会产生裂纹，严重影响器件的性能和使用寿命。因此，设计了一种新型功能梯度环形压电换能器（FG-rPET），并构建了一个精确的分析系统，主要包括一个三端口机电等效电路模型（EECM），可以获取径向振动的精确解。此外，所提出的三端口 EECM 具有出色的通用性，这也适用于传统的 rPET。通过实验和有限元法验证了EECM的有效性。振动特性（共振/反共振频率和有效机电耦合系数（k_eff )) FG-rPET 的基本模式和第二模式可以通过不均匀性指数和壁厚进行调节。对于具有特定壁厚的 FG-rPET，可以在第二模式下获得显着增强的 k _eff。所提出的分析系统对压电器件的结构优化设计具有重要的指导意义，所设计的FG-rPET有望打破常规rPET的力学性能瓶颈。