Propagation of in-plane elastic waves in a composite panel

The paper presents certain results of the analysis of in-plane elastic wave propagation in a composite panel. This problem is solved by the use of the Spectral Element Method. In the current approach the composite panel is modelled by a 36-node spectral membrane finite elements with nodes defined at Gauss–Lobatto–Legendre points. As approximation polynomials the fifth order orthogonal Lagrange polynomials have been used. In order to calculate the element characteristic stiffness and mass matrices the Gauss–Lobatto quadrature has been applied. Numerical calculations are carried out for various orientations of reinforcing fibres within the panel as well as for various volume fractions of the fibres. It is shown that propagation of in-plane elastic waves in composite materials is a more complex phenomenon than in the case of isotropic materials. The velocities of the elastic waves and also the direction of propagation are functions of the fibre orientation and the relative volume fraction of the fibres.