Numerical Investigation on Bifurcation and Stability of Bolted Rotor Systems Based on Energy Perspective

Rotors serve as the core components in critical machinery, however the coupling of nonlinear factors—specifically nonlinear contact stiffness in bolted joints, oil-film forces, and rub-impact forces—often leads to unpredictable instabilities. To address the limitations of traditional vibration analysis in identifying transient bifurcations and complex nonlinear motions, this paper presents a numerical study on the bifurcation forms and stability of a bolted rotor-bearing system from an energy perspective. A dynamic model incorporating rub-impact, contact stiffness and Capone oil-film forces is established. Distinct from conventional Poincaré maps, a energy trajectory method is proposed to analysis the form of the rotor system. Specifically, the topological characteristics of the energy trajectory, such as the geometric splitting of energy loops and the disordered wireframe structure, are employed as the primary indicators. These indicators effectively distinguish between different bifurcation types and chaotic motions, providing a more intuitive visualization of instability boundaries compared to traditional discrete maps. The energy trajectory provides a more detailed description of the rotor’s motion patterns, capturing energy fluctuations that traditional waveforms miss. The comparison demonstrates that the proposed energy perspective is a sensitive and intuitive indicator for real-time stability monitoring in engineering applications.