Influence of contact interface friction of bolted disk joint on motion stability of rotor-bearing system

In rotating machines, bolted joints are widely employed to connect adjacent disks to make multiple parts into an integrated one. The contact interface, subjected to tangential force introduced by unbalanced forces during normal operation, influencing the rotor dynamics, especially in the presence of relative speed, is of interest for investigations. However, there are little researches on the rotor dynamics considering the contact interface friction of the bolted disk joint. Thus, a dynamic model of the rotor-bearing system is established, which considers the friction at the contact interface between disks, nonlinear oil-film force, etc. The nonlinear dynamic phenomena of the rotor system were investigated using the fourth-order Runge–Kutta method. Bifurcation diagrams, vibration waveforms, frequency spectrums, shaft orbits, and Poincare maps are used to demonstrate the diversity of the system responses. The results indicate that the rotor system exhibits a rich diversity motion states, such as periodic-1 motion, multiple periodic motion, and quasi-periodic motion. The parametric study about the effect of friction coefficient on rotor dynamics is also conducted in the present work, which shows that a larger friction coefficient will lead the system enters into an unstable motion state at high rotating speed, and make the system enters into multiple periodic bifurcations at a higher rotating speed. The corresponding results can contribute to the further understanding of the nonlinear dynamic characteristics of the bolted joint rotor-bearing system.