The Application of the Method of Fundamental Solutions to Solve Ultrasonic Guided Wave Scattering

In this paper, we propose a coupling technique of modified boundary element method (MBEM) and method of fundamental solutions (MFS) for solving the forward scattering problem of Love waves. First, the boundaries and interfaces of the intact structure is discretized for BEM formulation. To suppress spurious reflections brought about by model truncation, the far-field behaviors of guided waves are incorporated into the basic BEM equations as the modification items. Secondly, the scattered wave field, due to surface or internal cavities, is modeled as radiated from a series of "virtual point sources", which are placed within the actual flaw regions. The strengths of these sources are determined by free-traction conditions of total wave field on the cavity surface, which forms an MFS configuration. The MBEM and MFS parts are combined to form a total matrix, and the near-field displacements, far-field scattering coefficients for propagating modes, as well as the source strengths are solved simultaneously.