Structural modification based on measured frequency response functions: An exact eigenproperties reallocation

Abstract

A structural modification method based on frequency response functions is presented in terms of an inverse eigenvalue problem. The design objective is to derive multiple lumped mass, damper and stiffness modifications needed to reallocate eigenvalues and specify eigenvectors of an existing structure. A frequency response function-based substructure-coupling concept is used to get the system dynamic equations. A linear algebraic equation is finally obtained to identify the necessary structural modifications. The exact structural modifications are determined. The existence and uniqueness of exact solutions are also investigated. The feasibility of structural modification is examined under the restrictions of structural modifications in the case where infinite many exact modifications can exist. The proposed method was applied to an example structure. Based on experiment data, the minimum stiffness modifications were calculated. The result of application indicates that the suggested method can derive accurate structural changes just based on minimum number of measured frequency response functions. (C) 2000 Academic Press.