Modal and response characteristics of rotor with angle misalignment fault based on cross-coordinate system substructure modeling method

Finite element models are widely used in dynamic analysis of misalignment rotor, but present finite element rotor models cannot simulate the axis characteristics of angle misalignment rotor, which consistent with the one with no misalignment. For achieving the precisely modeling of angle misalignment rotor, a novel modeling method called cross-coordinate substructure modeling method is introduced to establish the model of misalignment rotor, in which different parts of rotor rotate around different axis. Based on this modeling method, the 3D solid models of angle misalignment rotor are established with the help of ANSYS, and the modal characteristics and critical speeds of the misalignment rotor are achieved through modal analysis and harmonic response analysis. The numerical simulation based on Newmark method and experiment tests is carried out to obtain the response characteristics of the rotor model under the combined action of unbalanced force and misalignment load. The results show that the modal “rotation of rotor” appears, and the more amounts of response peaks can be aroused in harmonic response analysis when the rotor occurs angle misalignment. The typical fault characteristics of angle misalignment rotor in the spectrums and orbit diagrams are generally consistent both in the numerical simulation and experiment test. The research results can provide a theoretical basis for simulation and identification of the misalignment fault in rotating machinery system.