Study On The Performance Of Piezoelectric Sensor Under High Strain Load

With the development of economic in our country, various types of large-scale structures, civil engineering structures, aerospace structures and other structures have been built and put into use. Because of the complexity of the service environment and various types of loads, damages usually occurred in the structures, which may result in economic losses and casualties. The security issues have attracted more and more attentions and the structural health monitoring technology has become one of the hot researches today.The piezoelectric (PZT) sensor can be used in active and passive structural health monitoring for its excellent properties, but the applications in practical engineering is limited for the bad performance under high strain load. Therefore, the performance of the piezoelectric sensor under high strain load is investigated in this paper.First, the strain transfer process between the structure, adhesive layer and PZT sensor was analyzed, and the factors influencing the strain transfer efficiency was obtained by theoretical method. Comparison and analyses of the strain transfer coefficients with different parameters were presented by combining FEM software and mathematical analysis software.Besides, an experiment was designed and carried out to verify the result of strain transfer model. The influence of Young's module and thickness of the adhesive layer on the strain transfer coefficient was obtained under the different bonding conditions.Then, the capacity of the PZT sensor under high strain load was developed by experimental method. The impedance signal and Lamb wave signal under different loads and adhesive conditions were defined to characterize the performance of the PZT sensor under high strain load.At last, a new type pre-stressed PZT sensor was investigated. The shrinkage deformation of the metal ring is used to apply preload to the sensor, which improves the strain capacity of the sensor.