High sensitive evaluation fatigue of plate using high mode Lamb wave

In this study, we investigate the influences of the material fatigue on the phase velocities of the Lamb wave. The propagation characteristics of the Lamb wave are predicted by simulations and measured in the experiments. It is found that the velocity shift of the high-order mode Lamb wave is more sensitive to the variations of elastic coefficients than that of the low-order mode. In a LY-12-CZ aluminum plate, the velocity shift of the A3 mode is about 9 times larger than that of the A0 mode. Therefore, it is suggested that the high modes of the Lamb wave could provide good sensitivity in the nondestructive examinations of the material fatigue.