| Electro-mechanical impedance (EMI) method is applied to structural health monitoring. It has attracted wide attention over the past decade. Changes of the structural mechanical impedance could be caused by the damage of structure. Electromechanical coupling effects of piezoelectric material could be used as structural mechanical impedance. It is difficult to be tested directly. So, structural damage could be presented by the changes of piezoelectric patches of sticking electrical impedance on the surface of the main structure. That is the basic principle. This technology is sensitive to minor structural damage on the early stage because of the high frequency scope of working frequency in the alternating electric field. However, structural health monitoring technology of piezoelectric impedance is hard to simulate correctly on the theory because of the complexity of damaged structure and mechanical models and difficulty of high-frequency analysis. So, it is also a method for qualitative monitoring.Finite element model of fine piezoelectric impedance could be applied to structural health monitoring. It is put forward to check high frequency analysis of electrical impedance and verify method effectiveness of structural health monitoring based on high-frequency electrical impedance signals. Effects of cohesive course and coupling effects of three things piezoelectric patches- cohesive course-main structure three things are considered. And universal finite element software ANSYS is utilized through the analysis method of three-dimensional finite element harmonic response. By this way, three-dimensional finite element models of coupling system with constitution of piezoelectric patches- cohesive course-main structure. Effects on signals of electric admittance caused by damage parameter are verified and effects on electric admittance signals caused by cohesive course are analyzed. Effectiveness of Electro-mechanical impedance (EMI) method applied to beams and slabs damage growth monitoring and possibility of laminated structural debonding are proved.Precise impedance analyzer HP4294A has been used for experiment research on beams,slabs and 3 floors of steel frames. The accuracy of theoretical calculation model has been verified through the comparison and analysis between experiment data and theoretical computational data. The health monitoring damage index is suggested by the experiment research of damaged beams,slabs and 3 floors of steel frames. This damage index could recognize damage degree and damage propagation tendency quantitatively. Finally, influence on piezoelectric patches conductance and susceptance signals caused by different temperature,voltage and length of wire is also being researched during the experiment. The above research work demonstrated that piezoelectric impedance technique on health monitoring could be applied on engineering practice.
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