| The external piping system of aero-engine is mainly used for the transportation of fluid medium and which is an important part of aero-engine.With the further development of the aviation hydraulic system to high speed and high pressure,the overall requirements for the pipeline system continue to improve,so the application analysis of pipeline system engineering needs increasingly urgent.External pipe of aircraft engine as the connection between the parts in the link,the influence of the vibration characteristics for aero-engine external components is very important,and due to the complexity of pipe diameter,shape change,have no fixed regularity,so for aeroengine external vibration response of the piping system is very necessary to make an accurate analysis.In this paper,the aero engine spacial pipe-clamp system is taken as the research object,and the stiffness characteristics of supporting clamps are analyzed.Based on the Timoshenko beam theory,the finite element model of spacial pipe-clamp system is established to analyze its inherent characteristics and vibration responses under different excitation environments.The main research contents of this paper include:(1)Based on the finite element method,a mechanical model for calculating the stiffness of single metal felt clamp was proposed,and the validity of the model was verified by static test.Based on ANSYS software,the static contact finite element model of the single metal felt clamp system was constructed,considering the influence of tightening torque and the friction between the metal wires in the metal rubber.The hysteretic characteristic curve was calculated through the relationship between force and deformation,and the validity of the simulation results was verified by the measured hysteretic curve.On this basis,the effects of external load,tightening torque and friction coefficient on hysteretic characteristics and stiffness were analyzed.(2)The stiffness calculation mechanical model of double metal felt clamp was established by using finite element method and contact element method,and the validity of the model was verified by stiffness tests.Considering the structural asymmetry and stiffness dispersion of the double metal felt clamp,a finite element model of the double metal felt clamp was established based on ANSYS software,and the stiffness calculation results of the finite element model were compared with the test results to verify.On this basis,the effects of tightening torque,friction coefficient and external load on stiffness are further discussed.(3)Considering the effect of elastic support of clamps,the mass matrix and stiffness matrix of Timoshenko beam element were derived by using the energy method,and the dynamics model of spacial pipe-clamps system outside aero engine was established by using the finite element method.The finite element software ANSYS and free modal tests were used to verify the validity of the spacial pipe modeling.On this basis,a dynamic model of the spacial pipe-clamp system was constructed by introducing the elastic support effect of clamp.The validity of the model was verified by ANSYS software and constrained modal tests.(4)Based on the hysteresis curve obtained from the clamping test,the supporting damping was calculated,and a bilinear stiffness and damping mechanical model of the clamping was constructed.The damping of the spacial pipe structure was simulated by Rayleigh damping.The vibration responses of the space pipe and clamping system under the basic harmonic excitation and the basic random excitation were analyzed respectively.On this basis,the vibration response test rig of spacial pipe-clamp system was designed and built to carry out vibration response tests to further verify the effectiveness of the model. |
