A Generalization of Spatial Model Identification by Using FRF Data

A new general formulation for the spatial-model identification of structures is presented. The method is based upon the knowledge of the FRF matrix and the derivatives of its diagonal entries (i..e driving points) with respect to the angular frequency: the formulation is exact either considering the presence of the damping (either hysteretic or viscous damping) or finite difference formula 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 structures (discrete system, finite element cantilever beam, finite element truss) are included in the paper together with some issues and recommendations for the application of the method by using effective experimental data.