Research And Application Of Structure Health Monitoring System With Active Multiple Activation

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...