Affiliation:
1. FST Settat, Morocco
2. CRMEF Settat, Morocco & FST Settat, Morocco
Abstract
In this chapter, we model by Finite Element Method (FEM) the Lamb waves' propagation and their interactions with symmetric and asymmetric delamination in sandwich skin. Firstly, a theoretical model is established to obtain the equation of lamb modes propagation. Secondly, dispersion curves are plotted using Matlab program for the laminate [0]4. The simulations were then carried out using ABAQUS CAE by exciting the fundamental A0 Lamb mode in the frequency 300 kHz. The delamination was then estimated by analyzing the signal picked up at two sensors using two techniques: Two Dimensional Fast Fourier Transform (2D-FFT) to identify the propagating and converted modes, and Wavelet Transform (WT) to measure the arrival times. The results showed that the mode A0 is sensible to symmetric and asymmetric delamination. Besides, based on signal changes with the delamination edges, a localization method is proposed to estimate the position and the length of the delamination. In the last section, an experimental FEM verification is provided to validate the proposed method.
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