摘要
发射换能器设计的发展主要有三方面的推动力：对水声传播的广泛研究确立了低频应用于长距离探测的优势，新的驱动材料和结构材料的发展使得换能器在性能方面得到提高，计算机技术的应用。自从八十年代早期，低频大功率发射换能器已成为声纳应用的首选目标，其中，弯张换能器是应用得最普遍、最理想的低频、大功率换能器。但由于弯张换能器的最大的缺点是设计比较复杂，阻碍了弯张换能器的发展。近些年随着计算机技术的发展，有限元应用于弯张换能器设计已成为趋势。本文采用有限元软件ANSYS设计了外部驱动的弯张换能器。
本文在回顾近些年换能器技术发展状况的基础上，阐述了设计低频、大功率换能器的趋势和问题，并给出了解决方法。推导了使用有限元分析压电体和声学流体的基本理论公式。随后对有限元分析软件ANSYS及其应用于换能器设计进行了简介。在论文的设计部分，对外部驱动的弯张换能器的频率特性、辐射特性及阻抗特性进行了详细的计算，对结构尺寸进行了设计优化。指出了阻抗设计是外部驱动换能器的主要问题。
根据优化设计的结果，进行了静态应力分析和动态应力分析，确保了后续装配过程的安全性。通过ANSYS中的后处理功能，提取了所设计的换能器在空气中和水中的电声特性。
基于以上工作，我们制作了外部驱动弯张换能器的实验样机，对实验样机的电声特性进行了测量，并与计算结果进行了对比。最后对论文遗留的问题和今后的工作方向给予了总结和归纳。
Development in the field of projector design is spurred on mainly by three motivating forces: the extensive research in underwater propagation establishes the advantages of increasing lower frequencies for long range detection, the advent of new active and structural materials leads to substantial improvements in transducer performance , applications of the computer technology. The low-frequency and high-power projector have became the primary candidate of sonar system application since the early 1980s.Among them, the flextensional transducers are the low-frequency and high-power projector applied the most widely and the most ideally. But the biggest disadvantage of flextensional transducer is the complicated design, has obstructed the development of flextensional transducer. Recent years, accompaning with the development of computer technology it has a trend which using the finite element method(FEM) to design transducers. This paper presents the design of outboard-driven flextensional transducer using FEM
software ANSYS.
This paper discussed the trends and problems in low-frequency and high-power transducers design and gave out the solutions based on review the development status in recent years. We deduced the basic theoretical formula for analyse piezoelectrics and acoustic fluid using FEM. Subsequently, we presented the brief introduction of finite element analysis software ANSYS and the applied method of designing transducers.
In the part of thesis's design, we calculated the frequency characteristics,radiation characeristics and resistance characteristics of outboard-driven flextensional transducer, and optimized the size of structure. We pointed out that the resistance was the chief problem encountered in outboard-driven flextional transducer design.
According to the results of optimizing design,we carried out the static stress analysis and the dynamic stress analysis, and insured the safety of the later assemble processes. We calculated the electro-acoustical characteristics of designed transducer using the postprocess functions of ANSYS.
According to the above work, we manufactured and measured the real outboard-driven flextensional transducer ,then comparing with calculating result. Finally ,we summarized the problems which have leaved behind and the work directions in the future.
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