Research On Stiffness Characteristic And Influence Rule Of Rotor Rabbet Connection Structure

As an indispensable structural form of aero engine rotor,the connection state and stiffness variation characteristics of the connection structure directly affect the working state of aero engine.At present,the research on bolt connection,spline joints and other forms of connection structure in the field of aero-engine has been carried out for many years and a lot of research results of engineering practice significance have been obtained.However,there are a few researches on the structure of rabbet connection.With the improvement of aero-engine performance in recent years,aero-engine needs higher requirements on overall weight,structural strength and stability.Because of its simple structure,simple assembly and no additional connecting parts,rabbet connection is widely used in modern aero-engine rotor structure.However,compared with foreign countries,there are relatively few studies on the structure of rabbet connection in China,and few scholars conduct in-depth studies on its stiffness characteristics.On the basis of the previous research results,this paper studies the stiffness characteristics and influence rules of the rotor rabbet connection structure,further determines the reason for the stiffness change of the rabbet connection structure under the working state,and provides some references for its structural design.The main research contents of the paper include:(1)Based on the analysis of the working principle and stress state of the typical aircraft engine rabbet joint structure,the finite element model of the rabbet joint structure was established to study various factors affecting the connection stiffness.The main parameters leading to the change of the stiffness of the rabbet connection structure are determined.The change rule of the stiffness of rabbet joint under external load is analyzed.It provides a reference for the further study of the reason of stiffness variation of rabbet structure and the influence of various parameters on its stiffness;(2)The interference of rabbet structure is one of the important factors that affect the connection stiffness and reliability.The variation rule of the interference of the rabbet fit surface under working condition was studied,and the variation rule and calculation method of the rabbet interference under the action of thermal load and centrifugal load were deduced;(3)The stiffness robustness of rabbet structure under transverse loading is studied.By combining theoretical analysis with finite element simulation,the distribution law of the pressure on the end face of the rabbet connection structure is analyzed.The critical moment value is used to represent the robustness of the stiffness of the rabbet joint.Sensitivity analysis was carried out to determine the sensitivity of different structural parameters and assembly parameters to the critical bending moment.The results have certain significance for the stiffness and robustness design of the rabbet structure;(4)The calculation method of the stiffness of the rabbet connection structure under working condition is deduced.This method is used to calculate the stiffness of the rabbet structure in a rotor system.On the basis of considering the stiffness loss of the rabbet connection structure,the comparison between the results of finite element simulation and modal test shows that considering the stiffness loss of the rabbet structure can improve the accuracy of the finite element calculation results.