Subsystem identification using hybrid assembly in the frequency domain

The paper considers the identification of a structural subsystem, starting from the Frequency Response Functions of the assembled system, and from information about the remaining part of the structural system (residual subsystem), i.e. the so called decoupling problem. A possible approach is direct decoupling, which consists in adding to the coupled system a fictitious subsystem that is the negative of the residual subsystem. Starting from the 3-field formulation (dynamic balance, interface compatibility and equilibrium), primal or dual assembly can be used. Compatibility and equilibrium can be required either at coupling DoFs only, or at additional internal DoFs of the residual subsystem. Furthermore DoFs used to enforce equilibrium might be not the same as DoFs used for compatibility, giving rise to the so called non collocated approach. In this paper, a hybrid primal-dual assembly is applied in combination with collocated and non collocated interface.