Nonlinear vibration characteristics of a rotor system with pedestal looseness fault under different loading conditions

Taking a single-span rotor system with two discs as the research object, the pedestal looseness fault is simulated by a piecewise linear spring-damper model, and this model is combined with the FE (finite element) model of the rotor system. Two different loading conditions are determined based on API Standard 617 and the spectrum cascades, rotor orbits and Poincaré maps are used to analyze the influences of the stiffness of non-loosened bolts, looseness clearance and rotating speed on the dynamic characteristics of the system. The results show that different bifurcation forms, multiple periodic, quasi-periodic and chaotic motions can be observed under two loading conditions, and the system motion is more complicated under the second loading condition. The results will provide theoretical references for fault diagnosis, dynamic design, and safe operation of the rotor-bearing system.