Dynamic Modeling of Welded Stiffened Structures Using Finite-Element Model Updating

Various studies have focused on modeling the contact characteristics at joint interfaces in dynamic systems. However, in prior studies, only single sources of uncertainty — such as material property parameters or joint contact characteristics — were considered, which limited the accuracy of dynamic models. To address the limited improvement in dynamic model accuracy resulting from the correction of a single uncertain parameter, this study comprehensively investigates the effects of substructure material properties and the stiffness of welded joints on model precision. This paper proposes a dynamic modeling method for welded stiffened structures based on finite-element model updating. Considering the tight contact characteristics of the welded joints and following the substructure synthesis theory, spring elements were used to model the contact stiffness, establishing a theoretical model of the welded joint. Material parameters and spring stiffness were set as design variables, and an objective function was constructed by incorporating the modal participation factor as a weighting coefficient. A finite-element model updating method was then employed to correct material parameters and identify equivalent stiffness, rendering an optimized dynamic model of the welded stiffened structure. The experimental damping ratios were used as input for the harmonic response analysis, and the numerical results were compared with experimental data. The maximum error in the natural frequencies was 1.45%, with an average error of 0.61%. The mode shapes exhibited strong agreement with experimental observations, and the average error in the resonance amplitudes of the frequency response functions was reduced by 12.20%. These results confirm the reliability and accuracy of the proposed method for the dynamic modeling of welded stiffened structures.