【作者】 汤珺；

【导师】 王殿富；

【作者基本信息】 哈尔滨工业大学 ， 工程力学， 2006， 硕士

【摘要】 结构健康监测是设备状态监测和故障诊断的基础,而智能材料与结构的应用是进行结构健康监测的重点。压电陶瓷能与基体材料很好结合,具有制备容易、耐热、耐湿、强度高、频响宽等特点,另外它具有正压电效应和逆压电效应,即当它受到机械力变形时,能产生电势,对它施加电压时,能改变其机械尺寸,因此它在智能材料结构中既能用作传感元件又能用作驱动元件。与其它压电陶瓷相比,锆钛酸压电陶瓷(PZT)有较好的机电耦合系数、压电常数、机械品质因数、居里温度和稳定性等,因此,PZT能广泛应用于智能材料结构中。本文研究的目的在于开发一个主动的健康监测系统,用压电激励器和传感器的嵌入网络诊断技术,来检测各向同性板中损伤的位置和尺寸。主动监测系统的基本思想是:采用驱动器在复合材料表面激发主动监测信号,与此同时传感器在同一表面的其他一个或多个地方接收结构响应信号,并对信号进行分析,据此对结构中的损伤进行监测。多激励是指用多个压电陶瓷做为激励源,而且每一个压电陶瓷都可以同时作为激励和响应,可以轮换使用,因此是多点激励,多点响应。多激励监测系统具有以下特点:灵活方便、损伤的定位准确度高,可以进行多点测量,反复定位。因此利用PZT进行做多激励结构健康监测有广阔的应用前景。本文对主动多激励结构健康监测系统进行了应用,对压电陶瓷应用于结构健康监测的原理进行了深入的研究,确定压电陶瓷尺寸和频率的对应关系,确定压电陶瓷的极化方式和电极引出方式。对铝板,复合材料板,支架结构进行了无损伤情况下的试验。对于无损伤情况,利用本系统对铝板结构使用四个传感器进行损伤前不同频率下信号的采集,验证了主动多激励方案的可行性。进行了损伤识别的简单试验,用同一个传感器采集损伤前后的信号,用信号的差异来表征损伤。求出对损伤比较敏感的参数—群速度;群速度的求取可以直接得出铝板的群速度色散曲线,从而把拉姆波分成S0和A0两种模式,S0模式用来检测金属结构表面的裂纹扩展,A0模式对监测复合材料的分层十分有效;由同一块板损伤前后的响应信号,求出了反映损伤的散射波,完成对损伤程度的识别。更多还原

【Abstract】 Structure Health Monitoring is the base of equipment status monitoring and failure diagnosing. Application of smart materials and structure is the main point of Structure Health Monitoring. Smart materials and structure have definite requirements of sensor components and driving components, for example, they can adhere well to the matrix and have higher strength, fatigue strength, more broad scope of frequency response and faster response speed, etc. Piezodielectric ceramics have characteristic of easily preparing, heat-resistance, wet-resistance, high strength and broad scope of frequency response, etc. Furthermore, it has piezoelectric effect and inverse piezoelectric effect, namely it can produce electric potential energy when it is transformed by mechanical strength and its mechanical dimension can be transformed when voltage is put on it. So it can be used as both sensor component and driving component. PZT have better electromechanical coupling coefficient, piezoelectric constant, mechanical quality factor, curie temperature and stability, etc. So, PZT can be used widely in smart materials and structure.Researches in this thesis aim to develop active Health Monitoring technology and use a diagnostic technique based on a built-in network of piezoelectric actuators and sensors was proposed for detecting the location and size of an damage in isotropic- plates. The ideas of Active Health Monitoring System are that use drives to activate signals of Active Health Monitoring and sensors on another place or other places mounted on the same surface to recieve response signals of structure simultaneously and analyze signals which are the base of analyzing damages in the structure. Multiple activation is that several piezodielectric ceramics are used as excitation sources, the neighboring piezoelectric discs used as sensors to record the propagating waves, and one piezodielectric ceramic act as both excitation source and response source, which can be used alternatively to form multipoint excitations and multipoint responses. So they have these characteristics which are agile, convenient, high veracity of locating damages and can be used to proceed multipoint measure and locate repeatedly. So it has wide application foreground to use PZT to conduct Health更多还原