A Spatial Model Identification by Using FRF Data

Conference: 1997 IMAC XV - 15th International Modal Analysis Conference Two general fomulations for thespatial-model identification of structures are presented.The methods are based either upon the knowledge ofthe FRF matriz and the derivatives of its diagonalrn&ies (i.e., driving points) with respect to the angu-1,~ frequency, or upon the knowledge of all the entriesof the FRF matrix: the formulations are exact alsoconsidering the presence of the damping (hystwetic orvisrnus damping) and also (for the fimt formulation)considering finite-difference formulae for the evalua-tion of the FRF derivatives (in this special cast! them&ad is equivalent to an other method proposed in thepast). Numerical examples on several undamped strut-tu7.a (discrete-system, finite-element cantilever beam,jinite-element toss) with comparisons between the twofomulations ale included in the paper together. withSOUP issurs and recommendations for the applicationof the methods by using e~erimental data.