Numerical simulation of Lamb wave scattering in semi-finite plates

A Finite Element formulation to model the Lamb wave scattering in homogeneous and sandwich plates is presented. Dispersion curves are calculated by solving a quadratic eigenproblem. A meshing criterion to obtain accurate results with linear and quadratic elements is provided. An absorbing boundary condition for semiinfinite plates is derived from the formulation and used to study the Lamb wave reflection by simple obstacles. A hybrid Boundary Element-Finite Element formulation to solve Lamb wave diffraction by defects with more complex geometries is also presented. Both formulations are checked with a series of test problems and they are shown to provide excellent results.