Research On Vibration Characteristics Of Blade With Viscoelastic Coating

Blade is a key component of aeroengine,whose reliability is of vital importance for the reliable operation of the engine.As is found out that,the high cycle vibration stress of the blades is one of the main factors causing the loss of blade efficacy.As an excellent damping material,viscoelastic material can significantly reduce the vibration by spraying it on the surface of the blade.But the material has some special mechanical properties,such as the reliability of frequency and temperature.So the research on the vibration characteristics of blade with viscoelastic coatings must be done.In this paper,several researches have been made as follow:1)The blade is simplified as a thin plate considering the real size of the blade.Focusing on the drawbacks of the traditional MSE method on the composite structure damping estimating,a modified MSE method is deduced.The adaption of such method is studied and the results show that the effectiveness grows when the gap of damping ratio between two layers grows,which meets the situation of this paper.2)A method of analyzing the vibration characteristics of viscoelastic composite structures considering the frequency dependence character of the viscoelastic material is introduced.Such method is mainly a iterative process based on the modified MSE method.The method is compared to the traditional complex eigenvalue method which is considered to be the direct but time consuming method to the solve such problem.The results show that the introduced method shows small error to the traditional method.3)After adding the viscoelastic layer,the natural frequencies of the composite structure become lower but the model shapes show no differences comparing to the uncoating plate.The variation tendency of the structural loss factors shows a peak,which is similar to the material loss factor.But the peak frequency of the structural loss factor is much higher than that of the material loss factor.4)A modal test to free bonded plate and composite plate under voice excitation is performed.The result shows good fitness to the method introduced,which proves the effectiveness of the introduced method.5)A blade with viscoelastic layer is designed and the influence of the viscoelastic layer`s parameters is analyzed,including the thickness of the layer,the spray form of the layer,the material parameters of viscoelastic material,based on the method introduced in this paper.