Dynamic model updating of a simulation casing based on experimental modal parameters

Abstract

Finite element analysis model is the discretion and simplification of actual structure. Due to some uncertain factors in the process of modeling, such as element type, material properties, geometric shape, the uncertainty of boundary conditions and so on, the finite element analysis model tends to have certain error, which will affect the accuracy of the analysis results. Therefore, model updating and validation are needed to improve the accuracy and reliability of the model. Model updating method based on the first-order optimization was employed to update finite element models referring to experimental modal parameters in the paper. Taking an aero-engine simulation casing as the research object, modal test was carried out to obtain experimental modes. Then the finite element software was used to calculate the corresponding modal parameters. The calculated modal parameters were compared with the experimental ones. As the calculated results obtained by the finite element method may be not so accurate, the test modal data was utilized to update the finite element model, and the modal parameters were selected as references for optimization. With the correction of elastic moduli in each part of the finite element model, modal parameters of the updated finite element model were obtained, and modes of the revised model were in good agreement with the experimental modal parameters. The modal frequency differences between the calculated and experimental results were significantly reduced and the modal shapes of them were identical. The results demonstrated that model updating method based on the correction of elastic modulus is feasible and suitable for the accurate finite element modeling of large and complex structures in engineering.