Identification of global modeshape from a few nodal eigenvectors using simple free-form deformation

Abstract

A new method, different from common eigenvalue extraction methods, was proposed by Li and Kikuchi (in 8th ARC conference, 2002). It consists of explicit finite-element method and eigenvalue-extraction method in time domain. Even though the new method performs well in extracting eigenvalues, it is difficult to identify global modeshape of the given structure due to large size of time history data. Only some eigenvectors of a few nodal points can be extracted. In this paper, we apply computer animation technique to identify the global modeshape from a few nodal eigenvectors. Free-form deformation (FFD) technique is simply modified—simple FFD—and applied to the identification of global modeshapes. The basic concepts that consist of simple FFD algorithm are Delaunay triangulation and barycentric coordinate. Some numerical examples show good performance for the identification of global modeshape of a given structure.