Research Study On Delamination Damage Detection Of Composite Plate Based On Active Lamb Wave Correlation Dimension

With the increasing demand for composite materials in aerospace,defense and other important fields,damage detection techniques in composite materials have attracted more and more attention.Delamination defects of composite materials are the most important failure forms of composite laminates,which seriously threaten the safe use of composites.Because of the small attenuation in the propagation of Lamb wave,it is very sensitive to the tiny damage inside the plate.Therefore,the damage detection technique based on Lamb wave is suitable for the damage detection of aerospace composite materials in a large area.In this paper,composite laminates delamination defects as the research object,analyzes the characteristics of Lamb wave propagation in composite panels and the finite element simulation,identification of delamination defects by using the correlation dimension of signal acquisition,combined with probability imaging algorithm to achieve the visual image of the delamination in the plate.Firstly,according to the theoretical equation of Lamb wave propagation in isotropic and anisotropic materials,drawing the Lamb wave propagation in composite laminates when the dispersion curves of Lamb wave excitation signal layout scheme selection and PZT sensor in composite board optimization.The basic principle of fractal theory is introduced briefly,and several commonly used fractal dimensions are compared,and the method of solving correlation dimension is emphasized.In order to solve the problem of packet aliasing of weak signals and reflected waves,a method of extracting the defect wave packet signal based on the group velocity dispersion curve is proposed,which improves the accuracy and accuracy of data analysis.The composite laminates model and its delamination defects are established by using ABAQUS finite element analysis software,and the parameters of the theoretical group velocity curve and the defect wave packet signal extraction algorithm are corrected.The correlation dimension of the signals acquired before and after the damage is extracted as the characteristic parameters to define the damage index,and the localization imaging of delamination defects in the composite laminates is realized.When the delamination defects of different sizes and depths are set in the finite element model,the change of the correlation dimension of the signals is acquired.In the environment of simulated noise and experimental noise,the correlation dimension used as the damage index algorithm is analyzed.