Research On Health Monitoring Using Traditional Piezoelectric Transducer And Metal-core Piezoelectric Fiber Rosette

Structure Health Monitoring(SHM)technique based on Lamb wave enable online detection for small damages in many advanced structures,which greatly improves the safety of structure.In this paper,the active SHM technology based on Lamb wave is deeply studied by using the traditional piezoelectric transducers and metal-core piezoelectric fiber(MPF).Firstly,basic theory and propagation characteristics of Lamb wave are introduced.The excitation method and the parameters of excitation signal of Lamb wave are analyzed.The interaction of software and hardware is realized.Secondly,the principle of tomography is studied.The signal difference coefficient is defined and the probability imaging method of damage localization is proposed.According to the working principle of SHM system,establishes the experimental platform and designs the damage monitoring program.The spatial resolution of monitoring area is calculated,also the localization of single damage and multi-damage are analyzed.Thirdly,the localization methods of different detection principle are analyzed,the relationship between spatial resolution and damage identification of different methods is discussed.The relationship between the signal difference coefficient and the severity of corrosion is studied,the existence of damage is judged and a method to identify the degree of corrosion is proposed.The influence of elliptical scale parameter on the damage localization are analyzed,also the corrosion damage and simulated damage are localized.Finally,against the disadvantage of traditional method which needs Lamb wave propagation velocity to locate the damage.This paper proposed a damage visualization method without requiring Lamb wave velocity using MPF rosettes which are sensitive to wave propagation directions.The response characteristics of MPF rosette are analyzed.The accurate relationship between the voltage response amplitude of rosette and Lamb wave propagation direction is obtained by the impact calibration method.The damage index is defined to detect the damage,and the damage localization method based on angle recognition is proposed.The angular resolution of monitoring area is evaluated.Experimental results indicated that the generator(linear PZT array)and receiver(MPF rosette)pair can localize the damages with high accuracy.