Dynamic Performance Analysis And Assembly Process Optimization Of Aeroengine Rotor Considering Joint Characteristics

The high-pressure rotor system of aeroengine is mainly assembled by bolted joints.Its dynamic performance directly determines the overall service performance and reliability of aeroengine,and the joint stiffness and additional unbalance have a significant impact on the dynamic performance of rotor system.Under the comprehensive action of structure-process-load,the stiffness and damping of the joint of high pressure rotor system have typical nonlinear characteristics.Under the combined influence of preload deviation and joint surface manufacturing error,the additional umbalance caused by bolted joints has typical uncertainty characteristics.It leads to frequent vibration out of tolerance during assembly and commissioning,which affects the assembly quality and efficiency of aeroengine rotor.In order to solve the above problems,this dissertation studies the mechanical characteristics of aeroengine rotor bolted joints,the dynamic characteristics analysis considering the characteristics of bolted joints,and the optimization method of assembly process.The main research work is summarized as follows:(1)Test and analysis of nonlinear mechanical characteristics of bolted joint for aeroengine rotor:Aiming at the problem that it is difficult to accurately characterize the dynamic parameters of multi bolt joint,taking the typical bolted structure of aviation high-pressure rotor as the research object,combined with the harmonic balance method,the tangential dynamic parameter characterization model of joint is established.It is found that the tangential stiffness of bolted joints changes nonlinearly with the influence of assembly parameters,external excitation and other factors,and when the bolt tightening torque reaches a certain value,the dynamic parameters tend to be stable.Based on the mechanical model of the joint and the hysteresis loop test experiment,the tangential stiffness model of the joint in the viscous and micro-sliding stage is accurately characterized,which provides key data support for the dynamic characteristic analysis of the rotor connection structure of aeroengine.(2)Dynamics modeling and dynamic characteristics of multi-joint connection structure for aeroengine rotor:In order to solve the problem that it is difficult to analyze the mechanical characteristics and rotor dynamic characteristics of the joint efficiently and accurately,the hierarchical modeling is carried out based on the lumped parameter method and the finite element method,and the dynamics model of the rotor connection structure considering the mechanical characteristics of bolted joints is established.The effects of joint dynamic parameters unbalance distribution and other factors on the steady-state response of rotor system are proved.It is found that the decline or loosening of flange preload has little effect on the low-order natural frequency of rotor system,but local high-order mode jump will occur.The accuracy and efficiency of the dynamic reduced-order model of multi-joint connection structure of aeroengine rotor is verified by numerical simulation analysis,which provides a theoretical basis for the dynamic design and assembly process optimization of rotor system.(3)Research on dynamic characteristics of aeroengine rotor under uncertain excitation:In view of the uncertainty of the unbalanced quantity caused by factors such as the quality of parts,processing and assembly quality,which in turn affects the steady-state response of dynamics,a modeling method of uncertainty parameters is proposed,and then a rotor connection dynamic model with interval uncertainty parameters was established combined with the dynamic model of the rotor connection structure.Then combine interval theory and finite difference method to obtain the dynamic boundary of the steady-state response of the rotor system.Based on the measured data of the simulated high-pressure rotor,the dynamic response law of the rotor system under uncertainty excitation is analyzed,which provides a reference for the dynamic performance optimization of the rotor system.(4)Research on optimization method of aeroengine rotor assembly process for dynamic performance:For the problem of the single-objective optimization process method cannot meet the assembly accuracy and dynamic performance at the same time due to the complex coupling relationship between the initial unbalance,coaxiality and vibration response in the assembly process of the rotor system,this dissertation reveals the cumulative mechanism of coaxiality and unbalance error transfer of rotor assembly system.Then the prediction model of the coaxiality and unbalance of the rotor system is established,and the dynamics model of the rotor connection structure is combined to obtain the vibration response under different assembly conditions.Finally,a multi-objective optimization method of assembly process considering coaxiality,unbalance and vibration response is proposed.The results show that the multi-objective optimization assembly method based on assembly accuracy and dynamic performance is the optimal assembly strategy,which can reduce the vibration amplitude of the key nodes of the rotor system while ensuring high assembly accuracy,and achieve the low-level vibration of the entire rotor system.