Nonlinear Substructuring Using Fixed Interface Nonlinear Normal Modes

This study introduces a nonlinear dynamic substructuring (NDS) method assembling a truncated number of nonlinear normal modes (NNMs). A generic nonlinear structure is first divided into substructures and each substructure is reduced by taking a truncated number of fixed interface NNMs in addition to the proposed nonlinear constraint modes at each energy level. Using this basis a reduced quasi linear model of the substructures is computed at each energy level. Then the assembly of the quasi linear substructures using the Component Mode Synthesis (CMS) method yields the NNMs of the whole structure. The proposed method can be considered as an extension of the Craig-Bampton (CB) method for nonlinear structures. In order to evaluate the performance of the proposed nonlinear Craig-Bampton (NCB) approach, it is applied on a numerical example and the substructuring results are validated.