在功率超声以及水声技术领域，换能器的辐射功率及声波处理范围是两个重要的参数。本项目提出一种径向夹心式压电陶瓷复合超声换能器，目的在于实现换能器的二维大功率声辐射。该换能器是由径向极化的压电陶瓷圆管及金属圆管在径向复合而成。首先从理论上探讨此类换能器的解析设计理论。分别基于平面应力、平面应变以及耦合振动理论，推导薄圆环型、长圆管型以及粗短圆柱形径向夹心式压电陶瓷复合换能器的机电等效电路及共振频率方程。在此基础上探讨换能器的机电性能参数与其几何尺寸、振动模态及负载的依赖关系。其次，利用数值方法对换能器的径向振动模态、频率响应、位移分布以及辐射声场进行数值仿真，给出换能器的径向振动位移分布和辐射声场与其振动模态及负载阻抗之间的关系。最后，利用阻抗分析仪、激光测振仪及超声C扫描等测试系统对换能器的机电等效参数、振动位移及辐射声场进行实验研究，为此类换能器的优化设计提供理论及实验数据。

With the developemnt of high power ultrasonics and underwater sound technology, the requirement for more power and wide action range of the transducers is becoming more and more pressing. In this project, a new type of radially sandwiched piezoelectric ultrasonic composite cylindrical transducers are presented and studied. The objective of the project is to develop a new kind of high power ultrasonic transducers with two-dimensional acoustic radiation. The transducer is composed of the radially polarized piezoelectric tubes which are sandwiched between the inner and outer metal tubes. First, the analytical theory of the radial composite piezoelectric transducer is studied. Based on the plane-stress, the plane-strain and the radial-longitudinal coupled vibration theory, the exact analytical theory and the corresponding electromechanical equivalent circuit for the thin composite transducer with small height-radius ratio, the long composite transducer with large height-radius ratio, and the short composite transducer with in-between height-radius ratio are analyzed and given. Based on the electroemchanical equivalent circuit of the composite transducer, the resonance/anti-resonance frequency equations are obtained and the relationship between the electromechanical characteristics of the transducer and the geometrical dimensions, the vibrational modes and the load impedance is analyzed and given. Second, the finite element method is used to simulate the radial vibration of the radially sandwiched piezoelectric ultrasonic transducer. By using the ANASYS and ATILIA simulation program, the vibrational mode, the frequency response, the vibrational displacement distribution and the radiated acoustic field are theoretically simulated and compared with the analytical results. Finally, the electromechanical parameters, the vibrational displacement distribution and the radiated acoustic fields are measured by using the Impedance Analyzer, the Laser vibrometer and the ultrasonic C-Scanning system and compared with the analytical and numerical results. By means of the analytical theory, the numerically simulated and the experimental results, the radially sandwiched piezoelectric ultrasonic composite transducers are optimized and the conclusions can be used in the engineering design of the composite transducers with high power and wide action range.