Thin Plate Structure Impact Localization Based On Pzt Array And Passive Wave Method

Thin plate structure is widely used in engineering field as a bearing system,and the impact damage of thin plate structures may bring casualties and catastrophic consequences.Attention should be paid on the characteristics of Lamb wave generated by impacts and accurate determination of impact position when it comes to the monitoring of impacts on the thin plate structures.However,there are few related researches and many unsolved problems in this field.In this paper,a combination of theoretical analysis,experiment and simulation verification was carried out on the impact monitoring of thin plate structures,which aims at proposing a method of impact localization based on piezoceramic(PZT)array and passive wave method.The main contents are as follows:Firstly,the mechanism of Lamb wave generation and propagation in thin plate structure was introduced,dispersion equation of Lamb wave in thin plate structure was derived based on the theoretical analysis on the characteristics of Lamb wave propagation,the MATLAB calculation software was adopted to numerically solve the dispersion equation of Lamb wave in thin plate structure,and the group velocity and phase velocity dispersion curve of 1 mm thick aluminum plate were drawn.Secondly,based on the Lamb wave characteristics and hyperbola definition,a localization algorithm using a PZT sensor array and passive wave method was proposed,according to the localization algorithm,a square PZT array was designed.The purpose of the proposed impact localization method was to pinpoint the impact position with the characteristics of fastness and accuracy,which laid the foundation for impact monitoring on thin plate structures.Thirdly,a test system was set up to localize the impact points on thin plate structure.It mainly includes:performing spectrum analysis with Fourier transform on the collected impact signals;using DB wavelet decomposition to process the impact signals,separating and identifying A0 mode of Lamb wave in the detail signals for positioning test;determining the group velocity of A0 mode Lamb wave by dispersion curve,the group velocity can be used to characterize the speed of wave propagation in thin plate structure;using threshold method to determine the time delay of signals received by different sensors,the head A0 mode Lamb wave peak was selected to determine the time delay in the test;using the hyperbolic localization method which is based on wave propagation time difference of arrival(TDoA)to calculate the impact position;the impact point was localized according to the time delay of the signals received by different sensors in the array,and the accuracy of the proposed localization method was verified.Finally,the ANSYS/LS-DYNA finite element software was used to simulate the impact localization of a thin plate structure.The propagation characteristics of Lamb waves were studied by analyzing the stress propagation of the thin plate structure in the Y direction(perpendicular to the direction of thin plate).The PZT positions in the actual test were selected as the observation points,and the displacement time history curves in the Y direction were used to localize the impact points instead of the electric impact signals.The displacement signals in the simulation and the electric signals in the test were compared,and the proposed impact localization method was used to locate the impact point in the simulation,which also verified the accuracy of the proposed localization method.In this paper,the passive wave method was used to test and simulate the impact localization on thin plate structures,and the effectiveness of the proposed localization method was verified.In the experiment,PZT sensors were used as the receiving device of the impact signals,and a set of convenient and effective test system was established.Based on MATLAB language,a program for thin plate structure impact localization and error calculation was compiled.Both the test and simulation results showed that the thin plate structure impact localization method using passive wave method has great feasibility and accuracy.