Research On Piezoelectric Impedance Technology For Structural Health Monitoring

Piezoelectric impedance technology which is based on smart material is a brand-new method for structural damage detection, and it could be widely applied in structure health monitoring field. In this paper,the new method based on the piezoelectric impedance technology to detect the structural damage is introduced and the basic theory is analyzed. Then numerical analysis using FEM and two types experiments including bolts looseness and structural crack are studied.The main contents are as following:1. The electromechanical coupling property is analyzed,and the interaction between piezoelectric elements and structures as well as the relation between the mechanical impedance and electric impedance is deduced. In addition, the basic principle of piezoelectric impedance technology for structure health monitoring is analyzed.2. A brief introduction of the FEM and the FEM software ANSYS applications in piezoelectric impedance analysis is given.The structural crack affection on modal frequency is studied .The piezoelectric frequency-admittance spectrum under two kinds of harmonic excitation including pressure and voltage are deduced. The results show that piezoelectric impedance analysis using FEM is able to distinguish architectural tiny defection and to estimate the elementary expansion of crack.3. Using a steel plate with crack and an aluminum plate with bolts fixed as examples, the change of impedance signatures is examined by PZT patches. Experimental results show that the bolt looseness at different places and beam crack of different sizes can be detected successfully.4. The concept of health index is introduced . The damage is quantified by the root-mean-square deviation (RMSD) index. The RMSD index are reflect the location and extent of the damage.