Abstract:
To overcome the difficulty in the detection of layered defects in aluminum-based glass wool laminates, the dispersion characteristics of Lamb wave in the structure were analyzed by the finite element method. The dispersion curve of symmetric and antisymmetric modes in the laminated plate was obtained.It is found that the propagation characteristics of Lamb wave in the laminated plate are periodic distribution and have strange modes which are composed of the aluminum base layer and glass wool layer's mode mixing. In order to further analyze the propagation characteristic of Lamb wave in the aluminum-based glass wool laminatesand the interaction with layered defects, the propagation characteristics of Lamb wave and its interaction with defects were simulated based on the finite element transient analysis.The results show that the simulations are well matched with the calculation of finite element characteristic frequency method. When A2 mode is 53 kHz, the ideal echo signal can be obtained, and the energy distribution of wave-structure is more homogeneous. This type of frequency points can be used to locate the defect location; Using the difference calculation of the health signal and the defect signal, the position of the defect can be accurately positioned by the wave envelope centroid method, which supports the feasibility of the method.