抄録
In this paper, the authors present some theoretical discoveries about the relationship among rigid body properties, modal parameters and spatial matrices at first, and then consider the uniqueness and nonuniqueness of solutions in experimental identification from the view point of its practical availability. The theoretical discoveries are of structural dynamics under the free-free boundary condition. That is, "Independence of rigid body properties from elastically deformed natural modes" and "equation of momentum conservation in the form of spatial matrix, natural mode and frequency response function". It is concluded from the consideration of the uniqueness and non-uniqueness of solutions that non-unique solution is available in structural dynamics.
