Methods for modeling stiffness and model updating for the rod-fastened rotor of gas turbine

It is necessary to raise the computing efficiency and accuracy of the beam element model in the dynamic analysis of the rod-fastened rotor of a gas turbine. In our study, the spring connection elements were adopted to model the decrease in bending stiffness of rotor sections with abrupt changes in the diameter and contact interfaces. The stiffness values of the spring connection elements and the physical parameters of the rod-fastened rotor were obtained by the model updating method. The method proposed retains the physical meaning of the model. In addition, the model of a simplified experimental rod-fastened rotor was established and updated. The results show that the calculated eigenfrequencies are in reasonable agreement with the experimental data. It appears that the beam elements model of the rod-fastened rotor obtained by the proposed method has higher computing efficiency and accuracy in the unbalance response analysis, transient response analysis, and mode-based fault diagnosis of rotors.