| As a kind of complex mechanical equipment,the aeroengine is assembled from various components.Bolted joints are one of the important joints methods.Because the bolted joints are widely used,their performances are bound to have an impact on performances of the aeroengine.With the development of aeroengine towards high speeds,high thrust-to-weight ratios and high power,the impact of bolted joints on the performance of aeroengine has received increasing attentions.The mechanical properties and stabilities of the bolted joints have an essential influence on the structural performances,stabilities and reliabilities of the aeroengine.In this paper,the static and dynamic characteristics of bolted flange joints in aeroengine are studied.The related work is carried out around the assembly performances,vibration characteristics,stiffness characteristics and sealing characteristics of bolted joints.A method is proposed for determining the number of bolts.The main research contents of the paper include:(1)Based on the actual engineering background of the aeroengine,the stiffness characteristics of the bolted joints are analyzed.Firstly,the bending stiffness model of bolted joints is established,which lays a theoretical foundation for the analysis of bending stiffness.Then the T700 aeroengine power turbine structure is taken as the research object.Considering the external load caused by rotor misalignment,the preload,bolt diameter,the number of bolts and bolt distribution circle radius are studied,which has great significance to the design of bolted joints in aeroengine.(2)In order to analyze the vibration characteristics of the bolted flange joints,the disk-drum bolted joint is taken as the research object,and its inherent characteristics are studied by theoretical analysis,finite element simulation and experimental methods.The influence laws of the number of bolts and the tightening torque are obtained.The experimental data are used to compare and analyze the accuracy of different spring dynamic model methods,which provides reference for the improvement of dynamics modeling method for bolted joints.(3)In view of the problem that the bolt preload changes during the assembly process,the relevant research on the assembly performance of the bolted flange joints is carried out.Based on the elastic interaction,the formulas of change of bolt preload under different assembly sequence are derived,and the variation law of bolt preload is revealed.On this basis,the influence of different assembly schemes on bolt preload is analyzed,and the effect of elastic interactions is demonstrated by experiments.(4)Based on the existing method of determining the number of bolts,a method is proposed for determining the number of bolts of bolt-flange joints considering comprehensive performances.The method takes into account the reference value of the bolts spacing of the flange structure in the mechanical design manual,which satisfies the basic strength and tightness requirements.Through the theoretical model calculation and the finite element simulation method,the sealing characteristics,stiffness characteristics and assembly performances are studied to determine the range of corresponding number of bolts and give the range of corresponding number of bolts according to different working conditions,which provides a new idea for determining the number of bolts. |
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