Substructures’ coupling with nonlinear connecting elements

The analysis of complex structures is often very challenging since reliable data can only be obtained if the underlying model represents properly the real case. Thus, nonlinearities should be considered if their effect can significantly affect the results. In many cases, the relevant nonlinearity is concentrated on the junction between the components of the system (bolted joints, contacts, etc.). In this work, modal substructuring methods are used to get the behaviour of complex linear systems which are coupled through a nonlinear interface. This can be modelled as an additional substructure to be included in the substructuring process. The dynamic behaviour of the nonlinear connecting substructure is evaluated through the computation of its nonlinear normal modes. The proposed method is applied to lumped parameter systems connected by cubic springs as nonlinear elements. Two scenarios are analysed: the former considering a single nonlinear connection and the latter accounting for multipoint nonlinear connection, being more representative of real cases.