Identification of dynamic properties of thin-walled welded structures

Predicting the dynamic properties of welded machine tool frames of is of key importance at the design stage. However, it is a complex issue, especially when damping is concerned. The paper presents the method of modeling welded structures based on finite element method and model updating. According to proposed pro- cedure the finite element model of the welded structure is obtained by coupling its updated components. The model updating process is based on a substructural identification algorithm. The parameters of the weld model are extracted based on the isolated welded joints present in the modeled structure. The application of the method is presented on the steel welded frame example. Model verification consisting in comparing the results of the finite element analysis with the results of the experimental modal analysis carried out in the form of an impulse test showed that the relative error for natural frequencies did not exceed 4.1 %, on average 1.1 %. In addition, an average relative error determined for dominant resonances amplitudes for receptance was 16.5 %.