“…In several applications, when solving the inverse problem, it is often reported, (see for example references [4}10]) that the problem equations become ill-conditioned. In Sehlstedt [11], a well-conditioned technique for obtaining the spatial and frequency-dependent boundary traction vector is proposed. However, when using the method proposed here for obtaining the boundary traction vector, for example, at interfaces between structural parts, there is no problem with ill-conditioning; moreover, the dynamic stress tensor and needed traction vectors are obtained, not just on the boundary but, in the whole structure.…”