The Nonlinear Dynamic Analysis Of Rotor System With Rubbing-fault

As the core component of rotating machinery,the stability of the rotor system will directly affect the operation state of the whole equipment.Once the faults occur in rotor system,the operation efficiency of rotating machinery would be reduced,and it may even cause great economic losses.As one of the most common fault types,rubbing-fault has the characteristics of high incidence and great harm.Therefore,it is very necessary to study the dynamic behavior of the rubbing rotor system,which can help to reduce the accident rate and unplanned shutdown,and provides some theoretical guidance for failure detection and optimal design of rotor system.This work takes the simplified models of rotor systems with rubbing-fault as research objects.On the basis of the Newton's second law,the motion differential equations in different systems are obtained.Then the effect of rubbing-fault on the dynamic behavior of rotor system is analyzed by using nonlinear theory and rotor dynamics knowledge.After that,the effects of system parameters on the response of the rotor system are also discussed through time domain waveform,axis trajectory,spectrum,phase diagram,Poincare map and bifurcation diagram.The main work of this paper is as follows:(1)In the single-disk rotor system with rubbing fault,the system response at critical speed is in the chaotic state when the stator stiffness is small,as the stiffness increases,this response gradually evolves toward the periodic state and becomes increasingly stable.When the rotation speed is choosed as the research object,the system response appears as periodic,chaotic and quasi-periodic motion in the low,middle and high speeds ranges respectively.With the increase of the eccentricity,the rotor system tends to be chaotic in the critical speed range,and the whole system becomes unstable.With the increase of friction coefficient,the vibration response of the system at critical speed gradually evolves from chaos toward the periodic and quasi-periodic state,while in the high-speed region,the quasi-periodic motion is always dominant.(2)In the double-disk rotor system with rubbing fault,the vibration response varies with the number of disks with rub-impact,and exhibits different dynamic characteristics in the critical and high speeds regions.When the lubricating oil viscosity is chosen as the research object,the main motion forms of the system exhibit as periodic,quasi-periodic and chaotic states successively with the increase of rotational speed,in the medium and high speeds ranges,the system response is sensitive to changes in viscosity,and tends to be periodic as viscosity increases,but at high frequencies,this change can hardly affect the vibration state of the rotor system.When the left-disk eccentricity is selected as the research object,the vibration response near the critical speed is dominated by chaotic solutions,and the operation stability decreases significantly with the increase of the right-disk eccentricity.(3)In the double-disk rotor system with coupling faults of loosening and rubbing,the system response exhibits different dynamic characteristics in high speed region when there is no rubbing,single-disk rubbing and double-disk rubbing.The change of loosened-support mass has little effect on the response of the system at low speed,at this time,the motion of the system is dominated by chaotic state,but when the rotating speed is high,the response of the system will transit from chaos to periodic state with the increasing loosened-support mass.