Identificazione del comportamento dinamico di una sottostruttura da misure di risposta sulla struttura completa

In this paper the decoupling problem, i.e. the identification of the modal properties of a substructure that is part of a larger structure, is considered. The dynamic behaviour of the whole structure, either in terms of frequency response or in terms of modal properties, is assumed to be known, together with the physical (finite element) model of the second substructure. The decoupling procedure recalls the modal based structural modification procedure. Typically, the theoretical model of the known substructure has many more degrees of freedom than those experimentally measured on the whole structure. Therefore, either an expansion of the experimental degrees of freedom or a reduction of the theoretical model are necessary to match theoretical and experimental data. The paper highlights the difficulties and analyses the requirements for the decoupling operation to be successful.