A comparative study on modal-based finite element model updating approaches using noisy measurements

In order to identify more accurate finite element (FE) model parameters for an as-built structure, experimental data collected from the actual structure can be used to update the parameter values. In practice, experimental data is inevitably contaminated with measurement noise, which may lead to inaccurate FE model updating. This research compares the performance of two model updating approaches under noisy measurements. The first approach minimizes the difference between experimental and simulated modal properties, such as natural frequencies, mode shapes, and modal flexibilities. The second approach minimizes modal dynamic residuals from the generalized eigenvalue equation involving stiffness and mass matrices. Numerical study of a 6-degree-of-freedom spring-mass structure is performed through Monte Carlo simulation that generates noise-contaminated modal properties. Performance of the two model updating approaches is compared. a numerical study of noise effect on the modal property difference approach through Monte Carlo simulation. This research compares the noise effect on the two aforementioned modal-based model updating approaches, i.e. modal property difference approach and modal dynamic residual approach. The rest of the paper is organized as follows. The formulations of both model updating approaches are presented first. Numerical investigation on a 6-DOF springmass structure through Monte Carlo simulation is then described, where artificial Gaussian noise is introduced into “measured” natural frequencies and mode shapes to be used for model updating. Performance of both model updating approaches is compared. Finally, a summary and discussion are provided. 2 MODEL UPDATING APPROACHES For a linear structural system, the system stiffness can be updated as: