Evaluation of matrix cracking in cross-ply composites using the finite element simulation of guided Lamb wave propagation

Nondestructive evaluation of mechanical properties and health monitoring of composite structures is of great importance. The aim of this research was to propose a nondestructive evaluation method based on the propagation of Lamb waves to investigate the matrix cracking damage in laminated cross-ply composites. For this purpose, after developing the finite element model of a glass/epoxy composite, the Lamb wave behavior was studied in two antisymmetric (A0) and symmetric (S0) modes with different excitation frequencies. The dispersion curves of the A0 and S0 modes of the Lamb wave are then obtained by considering different crack densities. It was observed that the effect of matrix crack density and the loss of mechanical properties of the cross-ply composites on the phase velocity of the S0 Lamb wave mode was higher than that of the A0 mode. Furthermore, the detection of matrix cracking was better performed using the Lamb wave velocity at high frequencies close to the cut-off frequency. It was observed that the cut-off frequency decreased by increasing the crack density, and the drop in the Lamb wave velocity increased by increasing the number of 90° layers in the cross-ply composite. It was concluded that the Lamb wave propagation simulation method can be used as a virtual laboratory for nondestructive evaluation of composites and detection of matrix crack density in them.