Substructural FRF based reduction technique for nonlinear systems

Prediction of the forced response of coupled structures in contact may become computationally expensive due to the nonlinearity in the system. However, the dominant nonlinearity in the coupled structure is localized at the contact interface which gives the opportunity to solve the nonlinear equations only for connection degrees of freedom (DOF) instead of whole structure. In this paper, a new reduction technique for dynamic analysis of nonlinear coupled structure in frequency domain, is presented. The method reduces the number of nonlinear equations to the half of the number of connection DOFs in the coupled structure. Notably, model order substructuring techniques such as fixed, free and mixed interface methods reduce the system to N nonlinear equations, where N is the total number of connection DOFs plus the number of modes included in each substructure. The performance of the method is examined through a case study, and it is shown that the method reduces the computational cost.