Frequency and time domain analysis of guided waves in plate-like structures

Finite element (FE) methods are widely used to simulate guided waves in structures where analytical or semi-analytical approaches are difficult to be adopted. The interaction of waves with discontinuities or inhomogeneity such as edges, holes or inner defects is the case where explicit FE integration can return very accurate results. However, it is often needed to rely on high computational time to characterize the whole spectrum of interest. Conversely, frequency domain analysis may offer great computational time saving. In this paper the two FE approaches are applied on isotropic and orthotropic plate-like structures. Two-dimensional models of isotropic plates without any damage are first used to compare the results obtained in the time (transient explicit) and frequency domain. The plates are modelled with 2D plane strain elements as those models reproduce the equivalent ones in the 3D case for isotropic materials. An inner damage, similar to a delamination, is then considered and the results achieved through the two approaches compared. The same analyses are carried out for composite plates. Finally, the effect of the plate boundaries is discussed using the two methodologies.