Two-Dimensional DtN-FEM Scattering Analysis of SH Guided Waves by Surface Plate-Thinning Defect in a Plate

This paper presents an efficient technique called two-dimensional Dirichlet-to-Neumann (DtN) finite element method (FEM) to analyze the scattering of Lamb guided waves through a plate with surface defect. Utilizing the mode orthogonality, the unknown tractions at virtual boundaries are expressed in terms of the unknown scattered displacements at virtual boundaries via scattered coefficients. After that, this relationship at virtual boundaries can be finally assembled into the global DtN-FEM matrix to solve the problem. Compared with the traditional FEM, this method has the advantage of dimension reduction and need no absorbing medium or perfectly matched layer (PML) to suppress the reflected wave. Besides that, the reflection and transmission coefficients of each guided mode can be obtained by simple post-processing using FEM configurations.