Understanding self-excited vibration mechanism with modal analysis theory

As a vibration phenomenon with significant harm, self-excited vibration has become a research hotspot across various fields. While it was extensively studied, there were few studies that focus on explanation of the self-excited vibration mechanism through modal analysis method. Our study presents an explanation of damping-driven and mode-coupled self-excited vibration mechanism and the distinction between them. Firstly, the feedback force is considered as an external force to the system, allowing the structural model to be decoupled by the real mode shapes of the structure. Furthermore, the divergence mechanism of the two kinds of self-excited vibration is analyzed in modal coordinates, and in particular, the modal coupling effect and mutual excitation relationship between modes are discussed in detail. A novel divergence criterion with simple formulas and wide scope of application is proposed based on this approach. Finally, simulation experiments are conducted on two different models to investigate the influence of each feedback force on system stability. The obtained results demonstrate the consistency of the proposed interpretation with the results of existing methods for self-excited vibration analysis.