Damage Location Technique Based On The Mechanical And Electrical Impedance Of Piezoeletricarray Technology

The stress of the metal structure of different position will be a large difference when equipmentin the process of long-term use. It will cause irreparable damage to the device while the structure ofthe early fatigue damage not timely found that the accumulated to a certain extent because of longinfluenced by complex stress in some local important structure. Therefore, real-time monitoring ofthe metal structure of the health, accurate identification of small fatigue crack damage is ofimportant theoretical and application value.In this paper, the mechanical and electrical impedance technology for damage monitoring ofaluminum plate crack damage class structure joint research. We bond PZT sensors in the structureof aluminum plate surface to measure electrical impedance between PZT and aluminum platestructure. Using principle analysis and experimental verification methods on the following aspectsof work and achieved certain results.(1) Put forward more simple method of measurement of the structure of the mechanical andelectrical impedance. With traditional measurement method, We use the impedance analyzermeasuring the mechanical and electrical impedance of the metal structure. It makes the electricaland mechanical impedance technique in the field of structural damage monitoring promotion form alot of limitations because of the impedance nanlyzer equipment cost is very expensive. In this paper,we use the serial fixed size the PZT output resister.The end of the series resistance voltage signal isprocessed by the signal conditioning. The resistance and the PZT are in series. So its voltage signalmodulation with PZT impedance information. Finally, the real component of measured impedancesignal will be extracted by modem.(2) Reasearch based on one dimensional damage from mathematical relationship between thedistance and structure of PZT impedance spectrum. We use the seven groups of the damage withdifferent distance from the PZT sensors. Comparison of the measured impedance spectra of theexperiments. Because the measurement is dynamic impedance, there will be a lot of data.Weextract the characteristics from the PZT impedance spectrum,and choose the optimal linearitycharacteristic as the damage index of the reference standard. Finally,We get linear fitting for thecharacteristics and damage distance change curve.(3) Using the eight groups of piezoelectric array of different distance measured damage of thestructure of the mechanical and electrical impedance. In each group of piezoelectric impedance spectrum,We use the same method to extract the characteristics of the PZT impedancespectrum.Finally, We get each group damage corresponding to the damage index of the distance.Itcan calculate the damage of the charateristics and the distance between the corresponding PZTthrough the damage index of each group of PZT by linear fitting formula.It can’t locationlization ofthe damage while we just get the value of the damage from each set of PZT piezoelectricpatches.We must use the algorithm to imaging location of damage.The research results show that the proposed test method in the field of structural damagemonitoring has certain using value.