Finite Element Modeling And Analysis Of Vibration Characteristics Of Hard Coating Blisk

In order to meet the increasing performance requirements of aero-engine,the blisk has been widely used.Compared with the blades and disks connected by the traditional mortise,tenon and groove devices,the blisk can obtain a larger thrust weight ratio and higher service efficiency.However,due to the "soft" structure and small damping,various vibration problems will occur during the working process,which greatly restrict the service life of the engine.As a new type of damping material,hard coating can be applied to the blisk to control the vibration problem because of its good performance.In this paper,a three-dimensional finite element model of the composite structure is established to analyze the vibration characteristics.The main research contents are as follows:(1)A high fidelity three-dimensional finite element analysis model is established for the real blade disk test piece,and the relevant experimental verification is carried out.Firstly,based on the three-dimensional finite element model,the finite element modeling process is introduced.Secondly,the coating method is selected through the modal test of cantilever boundary coating titanium plate structure.Then,CMS reduction model of the composite structure is built,which can significantly improve the solution efficiency on the basis of ensuring the accuracy.Finally,through the comparison of experiment and simulation,the rationality of the finite element model of is approved.(2)For the tuned blisk,the frequency veering phenomenon will occur during the vibration process and the vibration behavior of the composite structure will change in frequency veering region.In this part,the revelant problems of frequency veering of circularly symmetric structure is studied.Based on the theory of cyclic symmetry analysis,the method of solving the frequency steering curve is given,and the specific location of the frequency steering area is determined by the analysis of related examples.Then,by changing the parameters of hard coating(including coating thickness,elastic modulus of coating)and the structural properties of disk(aspect ratio of blade and coupling strength of disk),the change rules of frequency veering curve is analyzed.(3)In order to study the effect of hard coating on the vibration characteristics of mistuned blisk,it is necessary to analyze the vibration characteristics of the tuned and mistuned blisk.Firstly,the basic theory of calculating the natural frequency and vibration response of the mistuned structure is introduced.Then,the finite element model of the blade stiffness random mistuning under different standard deviation is established,and the relevant vibration characteristics are solved.Finally,the specific influence of the hard coating on the vibration characteristics of the whole blade disk is calculated and explained.(4)In actual engineering practice,the blisk is often used in high-speed rotating environment,so it is necessary to analyze the vibration characteristics of the rotating state.In this part,the calculation method of natural frequency in rotating state is introduced.Then,based on the established finite element model,the change rule of modal characteristics of composite structure in different cases(separately considering centrifugal force and coriolis force,simultaneously considering centrifugal force and coriolis force)is analyzed.Finally,the change rule of frequency veering of composite structure in rotating state is analyzed.The three dimensional model established in this paper can be used to quantitatively evaluate the vibration characteristics before and after the coating of the blisk,and the relevant research results can provide a reference for the damping design of the whole blisk coating.