| It is very important to give a robust health monitoring method for in-service structure, especially for incipient damage of structure. There are difficulties for traditional methods. So it's necessary to find a new one for health monitoring. Supported by the National Natural Science Foundation of China (No.50378041), the piezo-electricity (PZT) impedance method in structural damage detection was experimentally studied.Firstly, in this thesis the traditional methods of damage detection were discussed, then, the new method using the PZT impedance method to detect the structural damage was introduced in detail. The basic theory of the application of the PZT impedance method in structural damage identification was analyzed which includes the notion and feature of the intelligent material, the application of PZT in the intelligent structure, the basic theory of piezo-electricity vibration and the deduction the relation between PZT and the structure coupling electrical impedance. Based on this theory, the experiment of detecting bolts'loseness quantitatively was designed. PZT admittance spectrum curves with the change of torque of the bolt were captured. Damage states were quantitatively identified by using the mean square deviation between the damage condition and the complete condition. Good result was obtained with ideal repeatability. At last, the possibility of locating damage with array of the PZT patches and the suitable frequency band for damage detection of steel structure were discussed. The result reveals good application prospect.As a new damage detection method, the PZT impedance method is developing, and much endeavor needs to be done for its application in practice. Thus, further research is required concerning the utilization of the PZT impedance method in the type, dimension, position localization of the complicated structure.
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