Dynamic Characteristics Analysis Of Rotor System Considering With Time-varying Stiffness Rolling Bearings

As a core component of high-speed rotary machinery and equipment,rolling bearing-rotor system has a very wide range of applications in the field of engineering manufacturing and processing.The more common engineering machinery includes turbofan engines,high-power compression dryers and various types of electric motors.High-speed slewing bearings-rotor system at work will inevitably lead to the overall vibration of machinery and equipment,the vibration of the equipment will have a negative impact on the ability to work and work to reduce the stability of the equipment,leading to accelerated aging equipment,and even will Trigger more intense vibration,leading to accidents.In complex operating conditions,the rotor system will produce significant nonlinear vibration,while the stiffness of the rolling bearing will also exhibit strong time-varying and non-linear characteristics.In the past,the research on the rolling bearing-rotor system can be divided into two types.One is to consider the bearing stiffness as a fixed value to study the nonlinear characteristics of the complex rotor system.The other is to consider the variation of the time-dependent stiffness of the bearing when considering the simpler rotor system.In the actual whole system,the dynamic characteristics of the rolling bearing and the rotor interact with each other.Especially in the design and development of the turbofan engine,with the increasing requirements on the design and working performance of the engine,Bearing and rotor system is more critical for the overall analysis.However,there are relatively few studies on the dynamic characteristics of the bearing rotor system considering this factor.Therefore,in order to ensure that aeroengine performance is more in line with actual needs,to meet the optimization design of new engine and improve the dynamic characteristics of the engine,it is necessary to study the rolling bearing and rotor system as a whole system.In this paper,rolling bearing-single rotor system as the research object,mainly contains the following research:(1)The additional stiffness effect,additional damping effect and additional inertial force generated by the rotor system are deduced.The finite element method is used to establish the bearing-rotor system overall model considering the time-dependent rolling stiffness.The time-varying law of the bearing stiffness and the rotor nonlinearity Kinetic characteristics were analyzed.Establish the model of rolling bearing with double disk rotor,the dynamics equation is derived by using finite element method,the time-varying bearings stiffness affected by rotor axis locus is introduced,nonlinear behavior of bearing rotor system with time-varying bearing stiffness and the change rules of bearing stiffness are analyzed.(2)Use double disk rotor bearing system as a model,consider aircraft motion which are represented by the flight parameters as the convected motion of rotor system,and the additional effects of maneuver were used in the model,the varying bearing stiffness and dynamics characteristics of rotor system were studied under different maneuver state.(3)The impact force is introduced into the overall system of bearing-rotor system.Considering the single-point rubbing,the influences of bearing clearance,rubbing stiffness,blade number and eccentricity on the time-dependent stiffness of the bearing and the system dynamics are studied.For the rotor-bearing system with rub-impact fault,a new type of rubbing model considering the influence of the number of blades on the impact force is taken into account,taking into account the center-to-center deviation of the rotor or the deformation caused by the deformation of the casing,the nonlinear dynamic response of the system under the horizontal hovering condition is studied by numerical integration method.The bearing clearance,rubbing stiffness,leaf number and eccentricity and other factors on the system.(4)The model of bearing-rotor system with labyrinth seal was established.The influence of seal gas excitation force on the system was considered.The influences of eccentricity,maneuvering flight condition and rub-impact fault on the time-dependent stiffness and system dynamics of bearing were analyzed.The influence of rotor eccentricity,maneuvering flight condition and rub-impact fault on the dynamic characteristics of bearing-rotor system with gas seal is analyzed.The influence of rotor eccentricity,maneuvering flight condition and rub-impact fault on the dynamic characteristics of bearing-rotor system with gas seal is analyzed.