Research Of Vibration Characteristics And Energy Tracks Of Nolinear Dual-rotor System With Rubbing Fault

Rotor system is indispensable in rotating machinery,and its work efficiency and safety issues are closely related to rotating machinery.Taking an aero-engine as an example,the rotor is the core component of the aero-engine.When a fault is occurred on the system,it often leads to vibration problems and even major accidents such as plane crashes.In order to improve the thrust-to-weight ratio and fuel efficiency of an aero-engine,the clearance between the rotor and the casing will become smaller,and the status makes rubbing faults more likely to occur.The dissertation takes the dual-rotor system with rubbing faults as the research object,and uses the vibration energy analysis method to analyze the nonlinear vibration characteristics of the system in the energy space.Firstly,dynamics equations of three different single-rotor models according to the concentrated mass method are established.Based on these models and combined with structural characteristics of the actual aero-engine,a simplified dual-rotor model with an intermediate bearing and rubbing faults is constructed and dynamic equations of the nonlinear dual-rotor system with rubbing fault are derived.At the same time,vibration responses of the dual-rotor system when rubbing fault occurs are discussed.The rubbing fault often occurs before the dual-rotor system reaches critical speeds.When the radial stiffness of the casing in different directions is same,the rotor always move close to the casing,which is prone to produce larger amplitude,after the rubbing fault of the system occurs.When the radial stiffness of the casing in different directions is different,the rotor would fall off from the casing after running a period of time,which helps to prevent the continuous occurrence of rubbing faults.Secondly,considering the complexity of the nonlinear dual-rotor system with rubbing faults,and stability determination process of the Floquet theory after obtaining the theoretical solution of the system is derived in detail.Theoretical solutions of the dual-rotor system with rubbing fault are obtained based on the improved method,and calculation results are consistent with numerical simulation results,which proves feasibility of the method.Next,combined with related theories of nonlinear vibration analyses,the dissertation elaborates the vibration energy analysis method obtained by extending the phase space to the vibration energy space.This method is adopted to analyze and study the vibration mechanism of the system after the rubbing fault occurs.By introducing an energy supply function,the system energy changes after the occurrence of rubbing faults and when the radial stiffness is different are simulated,and the vibration change process of the system is quantitatively investigated.The results show that the migration process of energy tracks could well reveal changes in the vibration state of the system during the rubbing process.Finally,some experiments are carried out to verify the above simulation content.The experimental results are basically consistent with the simulation results,which verifies the vibration energy analysis method proposed in this paper.The research results of this paper will provide a theoretical basis for the nonlinear vibration response analysis and vibration control of the system...