论文总字数：35629字

摘 要

本文设计了一种基于MEMS的压电声学声纳换能器件。由于水下声纳大多为投撒式的一次性器件，用量大，因此要求器件应便于携带，对成本不敏感。本文从此水声应用的需求出发，拟设计一种基于MEMS工艺的声纳换能器件，来实现声纳器件的小型化、低成本、低功耗等特点。

本文从现有器件出发，利用COMSOL软件构建模型，进行有限元仿真，通过模态分析得到器件在所需的垂直方向上振动时的谐振频率，通过对比实测数据与仿真结果，来验证软件仿真的正确性。并进一步采用控制变量法，通过仿真得到器件的结构参数对器件谐振频率的影响。通过仿真发现，底柱体积越大、结构层厚度越小、结构层宽度越大、结构层连接梁越细、底膜杨氏模量越小，器件的谐振频率越低。同时，从水声应用的需求出发，提出了器件的目标参数：被动式声纳工作主频段为100Hz~1kHz，主动式声纳工作主频段为20kHz~100kHz。通过有限元仿真，找到工作在2kHz附近的频点参数：当底柱宽度和深度分别在原设计上放大2.5倍，结构层单侧宽度选为700um，结构层厚度为5um，梁宽度在原设计上减少5um，Si的杨氏模量改为140e⁹ [Pa]，塑料底膜的杨氏模量改为5e⁸[Pa]时，结构的谐振频率约为2.2kHz，接近被动式声纳目标参数上限端点值。

关键词：MEMS，声纳换能器，有限元仿真

Abstract

A MEMS-based piezoelectric acoustic sonar transducer device is designed. Due to the fact that underwater sonars are mostly disposable casting devices with large amounts, they are required to be portable and cost-insensitive. Starting from the requirements of underwater acoustic applications, a sonar transducer device based on MEMS technology is planned to realize the characteristics of miniaturization, low cost, and low power consumption of sonar devices.

Starting from the existing devices, using COMSOL software to build a model for finite element simulation, through the modal analysis to obtain the resonant frequency of the device in the required vertical vibration, by comparing the measured data and simulation results to verify the software simulation is correct. The control variables method is further adopted to obtain the structural parameters of the device and the influence of these parameters on the resonant frequency of the device.. Through simulation, it is found that the larger the volume of the bottom pillar, the smaller the thickness of the structural layer, the larger the width of the structural layer, the finer the connecting beam of the structural layer, and the smaller the Young's modulus of the bottom film, the lower the resonant frequency of the device. At the same time, starting from the requirements of underwater acoustic applications, the target parameters of the device are proposed: the main frequency band of passive sonar operation is 100Hz~1kHz, and the main frequency band of active sonar operation is 20kHz~100kHz. Through the finite element simulation, the frequency parameters around 2 kHz were found: When the width and depth of the bottom pillar were respectively enlarged by 2.5 times in the original design, the width of one side of the structural layer was selected as 700um, the thickness of the structural layer was 5um, the width of the beam is reduced by 5um in the original design, the Young's modulus of Si is changed to 140e9 [Pa], and when the Young's modulus of the plastic film is changed to 5e8 [Pa], the resonant frequency of the structure is about 2.2kHz, which is close to the upper limit of the passive sonar target parameter value.

KEY WORDS: MEMS, sonar transducer, finite element simulation

目 录

摘要 I

Abstract II

第一章 简介 1

1.1 现代声纳简述 1

1.1.1 声纳回声探测器 2

1.1.2 其它类型声纳 5

1.1.3 声纳技术的应用 6

1.2 MEMS声纳换能器 9

1.2.1 由赭石蝇启发的MEMS定向麦克风 9

1.2.2 紧凑型电动力学MEMS扬声器 12

1.2.3 适用于耳内应用的新型集成式全范围MEMS扬声器 13

1.3 项目意义 17

第二章 MEMS水声换能器 17

2.1 设计目标 17

2.2 设计方案 18

2.2.1 MEMS主动声纳换能器单元设计 18

2.2.2 MEMS被动声纳换能器单元 19

2.2.3 器件工作原理 20

2.3 技术路径 21

第三章 有限元仿真 22

3.1 现代声纳简述 23

3.1.1 几何建模 23

3.1.2 材料参数 25

3.1.3 边界条件设置 26

3.1.4 模型分网 26

3.1.5 静态仿真 27

3.1.6 模态分析 28

3.2 现代声纳简述 30

3.2.1 影响结构谐振频率的因素 30

3.2.2 2kHz频点仿真 33

第四章 总结与展望 33

4.1 总结 33

4.2 展望 34

致谢 34

参考文献 34

附录

第一章 简介

现代声纳简述

二十世纪电声换能器发展迅速，由于传感器在水下应用的地方数量不断增加，这种增长一直延续到二十一世纪。SONAR概念起源于第二次世界大战，其形成为声音导航和测距的缩写，如下图1为航空吊放式声纳，图2为水面声纳浮标，它是通过以下两种过程探测和定位目标的：被动声纳探测过程——通过接收从物体发出的声音；主动声纳探测过程——通过接收回声测距过程（主动声纳过程）声穿透的物体反射的回声。然而，通过声音在水下探测物体起源于19世纪，在第一次世界大战期间客船，S / S泰坦尼克号和潜艇活动的损失推动了声纳技术及其应用的发展。本文将讨论声纳技术的发展以及这些技术在民用和民用水下活动中的应用军事目的，重点是最近的发展。

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