摘要：在工业生产中，螺栓广泛地应用于结构之间的相互连接。在役使用过程中，螺栓经受长时间的循环载荷和强迫振动会出现损伤和松动现象，最终螺栓的失效会带来巨大的损失甚至是灾难。近年来，机电阻抗技术作为一种新型的技术被广泛地应用于螺栓松动的在线监测。

本文首先介绍了螺栓松动监测的意义和现状，接着引入压电方程，并阐述了机电阻抗的基本概念以及机电阻抗技术的检测原理。压电陶瓷晶片作为一种新型的智能材料，具有体积小、敏感性强、频率稳定、寿命长等优点。本文利用压电陶瓷晶片的压电特性，将其耦合在螺栓表面，改变螺栓预紧力，分析了压电导纳曲线及损伤指标(RMSD)随预紧力的变化规律。同时运用有限元软件ABAQUS对机电阻抗法进行数值模拟，提取压电单元的应力和位移计算其阻抗谱，得到在不同预紧力下的阻抗谱，并评估螺栓的松紧程度。结果表明，通过测量压电晶片的机电阻抗能够实现对螺栓松动的监测。

关键词：螺栓松动、机电阻抗技术、压电陶瓷晶片、数值模拟

Abstract：In the process of industrial production, the bolt has been widely used to fasten structures together. After a long period of cyclic loading and forced vibration, the fastened bolt will be loose and damaged. The failure of the bolt will bring huge losses and even the disaster. Recently, electro-mechanical impedance technology as a new type of technology has been widely used to monitor the bolt loosening.

Piezoelectric ceramic wafer, as a new type of intelligent materials has many advantages, such as small size, strong sensitivity, frequency stability, long life and so on.In present paper, the significance and present situation of  bolt loosening monitoring were introduced firstly. The piezoelectric equation, the basic concept of electro-mechanical impedance and the principle of electro-mechanical impedance are deduced. Then, the piezoelectric wafer was attached to the surface of the bolt. The admittance was measured by impedance analyzer. The relationship  between admittance and pre-tightening force was analyzed. A damage index was introduced to evaluate the bolt loosening. The electro-mechanical impedance of bolt was  also studied by finite element method. The stress and displacement of  piezoelectric element were extracted from the bolt loosening model. The impedance spectrum was obtained and used to evaluate the bolt loosening. The results show that the bolt loosening monitoring can be realized by measuring the electro-mechanical impedance of piezoelectric wafer.

Keywords: bolt loosening, electro-mechanical impedance method, piezoelectric ceramic chip, numerical simulation

目录

第一章绪论

1.1螺栓松动监测的意义和现状 1

1.2压电阻抗技术的发展 2

1.3压电阻抗法的特色及优点 2

1.4介绍主要研究内容 3

第二章压电晶片机电阻抗法相关理论基础

2.1压电效应和压电材料

2.1.1压电效应 4

2.1.2压电材料 4

2.1.3压电方程 5

2.2机电阻抗的相关理论基础

2.2.1基本概念 6

2.2.2机电阻抗法的检测原理 7

2.3机电阻抗法的损伤指标 9

第三章螺栓松动监测的相关实验分析

3.1螺栓松动监测的实验目的及主要内容 10

3.2实验装置 10

3.3实验方案 11

3.4实验数据处理 12

3.5实验结论 13

第四章螺栓松动监测的有限元模拟

4.1有限元数值模拟介绍 14

4.2螺栓松动监测的有限元模型

4.2.1前期准备 14

4.2.2ABAQUS建模过程 16

4.3数值计算结果分析

4.3.1图形处理 18

4.3.2分析结果 21

第五章结论与展望

5.1结论 22

5.2展望 22

致谢 24

参考文献 25

第一章 绪论

1.1螺栓松动监测的意义和现状