A finite element model updating method for local structures

For an actual structure, the modeling errors of the Finite Element Model(FEM) often only exist in some local area. A model updating method is presented to update the local structures. Firstly, according to the Frequency Response Function (FRF) decoupling method, the fitting FRF of the global structure is reconstructed from the residual structure FRF and the local structure dynamic stiffness including the parameters to be updated. Then, the iterative optimization process of maximum likelihood estimation is carried out to get the parameters minimizing the residual error between the fit value and the measured value. On this basis, the sensitivity of the residual error to the parameters is represented by the dynamic matrix of the local structure, and the fundamental equation for model updating is constructed. The measured FRF of the global structure is utilized to update the FEM of the separated local structure directly. Finally, numerical simulation of a jet plane and experimental investigation of the delta-winged aircraft are performed to validate the feasibility and efficiency of the present method. The obtained results show that the proposed method can be successfully used to update the model of the actual structure with modeling errors only in the local area, achieving a good agreement between the dynamic properties of the updated FEM and the actual structure. © 2020, Beihang University Aerospace Knowledge Press. All right reserved.