A spatial model identification by using FRF data

Two general formulations for the spatial-model identification of structures are presented. The methods are based either upon the knowledge of the FRF matrix and the derivatives of its diagonal entries (i.e., driving points) with respect to the angular frequency, or upon the knowledge of cell the entries of the FRF matrix the formulations are exact also considering the presence of the damping (hysteretic or viscous damping) and also (for the first formulation) considering finite-difference formulae for the evaluation of the FRF derivatives (in this special case the method is equivalent to an. other method proposed in the past). Numerical examples on several undamped structures (discrete-system, finite-element cantilever beam, finite-element truss) with comparisons between the two formulations are included in the paper together with some issues and recommendations for the application of the methods by using experimental data.