Propagation of in-plane waves in an isotropic panel with a crack

The paper presents certain results of the analysis of wave propagation in an isotropic panel with damage in the form of a fatigue crack. This problem is solved by the use of the spectral element method. In the current approach the panel is modelled by a number of 36-node spectral membrane finite elements with nodes defined at appropriate Gauss–Lobatto–Legendre points. As approximation polynomials the 5th 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. The crack can be of an arbitrary length, depth, and location. The elastic behaviour of the panel at the crack location is simulated as a line spring with a varying stiffness along the crack length. Numerical calculations are carried out for various locations of the crack in the panel as well as for the panel with stiffeners. The problem of the identification of the crack from the transmitted and reflected waves is also considered in the paper.