Research On Dynamic Behaviors Of A Rotor System Supported On Ball Bearings With Spalling Faults

Aero-engine and other industrial rotary machine are all developed in the direction of high speed and complex load.Therefore,the requirements for each rotating supporting part of the equipment become higher.Ball bearing as a rotating system commonly used support component,its crack,flake,deformation and failure can make large vibration of the rotor system and then bring greater security risk to the machine.Therefore,the study on the characteristics of fault bearing and the dynamic characteristics of fault bearing-rotor system has become an important subject in the field of rotor dynamics.The research of this field is not only important for bearing design and bearing fault diagnosis,but also for the research of high speed and high load rotor system.The spalling faults in bearing faults are mainly researched in this paper.The spalling faults in bearing rotor system are taken as the research object,and the fault bearing contact characteristics,stiffness characteristics and dynamic characteristics of rotor system are studied.The main research contents in this paper are as follows:(1)The influence of centrifugal force and gyroscopic moment at high speed are considered,and the influence of sliding are ignored to establish the quasi-static model of the five-degree-of-freedom rolling bearing.The Newton-Raphson iteration method is used to solve the nonlinear system of simultaneous equations,the contact characteristics of rolling bearings are analyzed,and the validity of the model and algorithm is verified by comparising with the literature results.(2)Aiming at a fault bearing,the bearing spalling fault is introduced into the model by the form of displacement excitation.Taking spalling fault ball bearing as the research object,a time variable stiffness model is set up,and the validity of the fault bearing model is verified.Based on the model of ball bearing with outer ring faults,the effect of axial load and running speed on the contact angle,contact load distribution and time-varying stiffness are researched.The research shows that once the ball bearing is faulted,the defect can cause the bearing load to be redistributed,which can affect the stiffness and the vibration characteristics of the system.(3)On the basis of the above studies,the dynamic model of the fault ball bearing-rotor system is established,and the bearing stiffness obtained by the above solution is introduced into the rotor system in the form of nonlinear restoring force.In contrast to previous studies,this paper considers the influence of bearing axial vibration on the nonlinear force.The influence of rotation speed and spalling size on the dynamic characteristics of the system is studied in different outer ring spalling fault,inner ring spalling fault and roller spalling fault of rolling bearing,and the bearing spallings are prediagnosed according to the response results.(4)Based on the effects of single spalling fault bearing on the dynamic behaviors of rotor system,the dynamic model of the compound spalling fault bearing-rotor system is established.The influence of the parameters on the system response was studied under bearing inner ring and outer ring spalling faults,bearing inner ring and roller spalling faults,bearing outer ring and roller spalling faults.