| The working blades of the turbine are often connected to the disk by a fir-tree tenon in modern aero-engines.The firtree tenon-mortise connection structure has the advantages of light weight,small size,reliable fixation,simple structure,convenient replacement,etc.In friction model modeling and calculation of tenon contact,contact stiffness and contact damping are very important parameters,which not only affect the resonance frequency of the blade,but also affect the dynamic properties of the blade.However,there is still a lack of effective models for contact stiffness and damping of complex tenon joints.In this paper,the fir-tree attachment of aeroengine bladed disk is taken as the main research object,and the contact stiffness and contact damping are identified through the method of combining test and simulation,and applied to the blade-disk rotor system to study its dynamic characteristics.The specific work in this paper is as follows:Firstly,simplified modeling was builded for the firtree tenon-mortise structure of bladed disk,and free-mode simulation and test of the blade and simplified disc were carried out to verify the modeling accuracy.Constrained modal simulation and experiments were performed to verify the correctness of boundary conditions,and obtain the modes of vibration and general rules of natural frequencies with centrifugal force of the structure.Secondly,contact characteristic simulation of this structure was run,and the bladed disk assembly model with thin-layer element was established according to the simulation results.The influence law of thin-layer element elastic modulus on the natural frequency of the structure was researched through the finite element simulation,and the error function of simulation and experimental results was created to realize the modeling and identification of contact stiffness.Then,the harmonic response simulation of the bladed disk structure with thin-layer element was run to obtain the change rule of the first-order acceleration response under various operating conditions with the thin layer element damping ratio.The dynamic response test of the bladed disk assembly structure was carried out to obtain the law of the first order acceleration response varied with centrifugal forces.The modeling and identification of contact damping are realizedthe by comparing calculation results with experimental datas.Finally,the established contact stiffness and damping model was applied to the bladed disk rotor configuration,and the modal characteristics and unbalance response of the rotor structure were simulated.The results are compared with those of the traditional blade rotor system without tenon joint structure,and the effects of contact stiffness and damping on the dynamic characteristics of the blade rotor system are evaluated And then aiming at the bladed rotor system with thin-layer elements,the influence of bearing support stiffness and unbalanced mass on rotor dynamic characteristics was investigated.This paper provided a new idea for dynamic modeling of bladed disk rotor system. |
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