Exact structural modification for eigenstructure assignment using frequency response functions

Abstract

A structural modification method based on measured frequency response function is presented in terms of inverse eigenvalue problem. The design objective is to derive multiple mass and stiffness modifications needed to reallocate eigenvalues and specify eigenvectors of an existing structure. For theory development, a substructure-coupling concept is introduced. The system equation contains FRFs at the designated modification points. The exact solutions can be determined straightforwardly by solving the derived linear algebraic equation. The existence and uniqueness of exact solutions are also investigated. Special attention is given to the case where infinite many exact modifications exist, in which the least modification can be determined. The proposed method is applied to an example structure by experiments. The result of application indicates that the suggesting method can derive exact structural changes just based on minimum number of measured frequency response functions.