Substructure-based model updating using residual flexibility mixed-boundary method

Substructure method has been widely applied in dynamic analysis of complex structures due to high computational efficiency. On the basis of Residual flexibility mixed-boundary (RFMB) substructure method, a model updating approach is proposed in this paper. Four major steps of the RFMB model updating method are summarized as: 1) Substructuring: Dividing the whole structure into residual part and reduced part according to the junction surface; 2) reduction: Using the RFMB component mode synthesis approach to reduce the order of each substructures; 3) assembly: Residual structure analysis by using the reduced assemble matrix; 4) updating: Model updating by solving the optimization problem. Numerical simulation is conducted to verify the effectiveness by adopting a cantilever plate in case I. In case II, the proposed method is applied to identify the elastic parameter of interface of a bolted joint structure using experimental data. After parameter identification, the maximum error between numerical results and the experimental data decreases to 2.44 %. And three component mode synthesis model updating methods: Craig-Bampton (CB), Mixed-boundary (MB) without considering residual flexibility and RFMB model updating approach, are applied to update the same bolted joint structure for comparing the accuracy. For comparing the computational efficiency, the RFMB model updating approach is applied to the complicated aero-engine casing structure. In case III, the average time-consuming of the Whole finite element model (WFEM) is 5.15 times to the Residual finite element model (RFEM) in the single updating iteration. Results show that the proposed approach has better performance in the finite element model updating.