Research On Damage Localization Of Thin Plate Structures Based On PZT And Lamb Waves Method

The detection technology based on PZT and Lamb waves method can monitor the structural damage online.The existing problems can be detected in time in the early stage of structural damages,and therefore the losses can be avoided caused by structural failure.Therefore,it has important research significance.Based on the PZT characteristics and Lamb waves theory,taking the thin aluminum plate as the research object,the Lamb waves active monitoring technology is applied to locate the damages in the aluminum plate,the experiments and simulation are combined to verify the results.The main contents of this paper are shown as follows:Firstly,the theory of elastic waves,Lamb waves and the propagation characteristics are introduced.The Lamb wave equations by the knowledge of elastic mechanics are derived,and then the Lamb wave equations are used to draw the dispersion curves of Lamb waves by using MATLAB.And then,the types and characteristics of piezoelectric elements are described and the PZT model is determined for this study.The PZT vibration modal analysis is simulated by ANSYS,and the best central frequency of the Lamb waves are determined.The excitation forms of Lamb waves are compared by MATLAB,and finally,the parameters of the Lamb waves of the excitation signal are selected.Moreover,the propagation processes of Lamb waves in both the health aluminum and damaged aluminum plates are simulated using ABAQUS and then the simulation results in the health aluminum plate and damage aluminum plate are analyzed to locate the damage in the aluminum plate,and the feasibility of the finite element method of the damage location by using the ellipse method is verified.And as well,the different damage models with the same location and different sizes are established using ABAQUS.By comparing the simulation results of Lamb waves propagation in different damage models,the relationship between the Lamb wave propagation energy and the damage size is discussed.Finally,the experiments of the detection the aluminum plate damage are conducted.The experimental platform is set up,the transmission,acquisition and processing of Lamb wave signal can be completed by LabVIEW software.Through the comparison analysis of the experimental data in health aluminum plate and the damage aluminum plate,using the ellipse method and the time delay principle,the location of the damage in the aluminum plate is studied.The advantages and disadvantages are compared between the three-point positioning method and the four-point positioning method,and it proved that the three-point positioning method can be used to locate the position of the damage in the aluminum plate.And as well,through the comparison of the experimental results and the simulation results,the accuracy of the Lamb waves method of detection the damage in the aluminum plate is verified.