Structural Health Monitoring Techniques Based On Pzt Impedance Analysis

In this thesis, the application of piezoceramic(PZT) impedance analysis approach in structure health monitoring is studied. By designing experimental platform, measuring signal, analyzing and processing data and comparing the PZT impedances of bolts in normal status and loosened status, the structure health status is monitored successfully.The principle, characteristic and development of structure health monitoring technology based on PZT impedance analysis are presented in detail at the beginning. Then the basic theories of structure health monitoring using PZT are introduced, including the concepts and characteristics of smart material and structure, the application of PZT in smart structure, some basic theories of piezoelectric vibration and the deduction of coupling impedance between PZT and structure. Afterwards the experiment of detecting bolts loosened is designed based on these theories, which includes designing experimental platform, choosing and sticking PZT, generating excitation signal, measuring impedance, sampling data, preprocessing signal and calculating impedance. From substantial experiments, the PZT impedances of bolts in normal status and loosened status are measured and compared, and their differences are separated successfully. Finally the method of judging structure health status using health index is discussed.The research results show that the PZT impedance analysis approach can be used to achieve real-time and on-line structure health monitoring correctly.