FEM analysis of dispersive elastic waves in three-layered composite plates with high contrast properties

The limitations of the dynamic theories for the thin layered elastic structures, which very often have different physical and geometrical contrast properties of the layers in today's high-tech applications, bring a number of challenges in the numerical computation of the dynamic response. This is a strong motivation to develop a suitable computational methodology for accurate evaluation and implementation of the numerical results, aiming at accurate interpretation of the vibration spectra and the associated displacement and stress fields. In this paper, a newly developed numerical engineering approach is presented for the study of elastic wave dispersion in composite plates (sandwich plates) with high-contrast properties of the layers using modal finite element method (FEM) analysis implemented in commercial software. The obtained results are compared with the iterative numerical solution of the Rayleigh-Lamb dispersion equation for the fundamental flexural wave and the first shear harmonic. It is shown that the complexity of the dispersion phenomena, including the cut-off frequencies of higher order vibrational modes, has been captured very accurately and that the developed computational methodology provides a valuable insight into the frequency range in which the respective mode can be activated. This perspective shows a great potential of the approach to be employed in many engineering applications involving multi-layered structures with arbitrary number of layers.