Damage localization in composite laminates based on a quantitative expression of anisotropic wavefront

In this paper, according to the disperse curve of composite laminates in a low frequency domain, a quantitative relation between anisotropic wavefront and propagation direction is proposed to reveal the direction dependency of Lamb wave propagation in composite laminates. This relation is described by a concise analytic expression, which can effectively incorporate anisotropic wave propagation into damage identification and reasonably determine the time-of-flight (ToF) of the Lamb wave. The reliability and applicability of this quantitative relation are validated by numerical simulations and experiments in three different lay-up composite laminates. Furthermore, combining this quantitative relation and the conventional ToF approach, an effective detection method is developed for damage localization in composite plate-like structures. By using PZT sensors, the method is conducted experimentally in a cross-ply laminate. The Gabor wavelet transform is introduced for signal processing to identify the ToF more exactly. Results indicate that a satisfied damage location can be achieved by considering the orientation dependency of anisotropic wave propagation in composite laminates.