Enhanced wavefield imaging method for impact damage detection in composite laminates via laser-generated Lamb waves

Full wavefield processing techniques are promising for damage detection and imaging. However, the high measuring requirements in space are labor-consuming. To improve the imaging quality of wavefields with limited scanning points, 2D interpolation methods are investigated with simulating wavefields. To detect the defects, a damage index called first-to-residual energy ratio (FRER) is introduced with considering the amplitude signatures of the first arrived Lamb waves and the residual wave components. It shows a remarkable sensitivity to the barely visible impact damage (BVID). Besides, to further improve the damage imaging resolution, a data fusion technique is employed by multiplying the sub-frequency features extracted from the broadband Lamb waves. Hence, the implicit information of broadband Lamb waves can be efficiently used. Finally, an experimental investigation was carried out on a T300 composite laminate with artificial impact damage. The results verified the efficiency of the proposed method.