Research On Bearing Characteristics Of Bump Foil Air Bearing Based On Curve Shell Model

Gas lubricated bearings play an increasingly important role in the industry with the development of high speed machinery.The bump foil radial bearing belongs to a relatively conventional gas dynamic bearing.Although it appeared earlier,it is still widely used in various industries.However,theoretical research on bump foil bearings has not achieved high precision yet.In the past studies,most of the wave foils were equivalent to a simplified model for calculation.The calculation process of the equivalent model is relatively simple,but the accuracy of the calculation results is limited.As the bearing speed in practical applications are getting higher and higher,and the load is getting larger,the calculation requires a more accurate theoretical calculation model in bearing design.The bump foil and the top foil are the important supporting components of the bearing.In this paper,a curve shell that can reflect the actual shape of bump is established for the foil,and the calculation model is established by the finite element method.The influence of the membrane effect on the curved shell is analyzed.The specific model is used to calculate the deformation of the shell.Compared with the simpler flat shell model,and comparing the same model with different amount of meshes in ANSYS,the accuracy of the curve shell model is verified.Since the top foil is smooth and flat and does not need to consider stretching,the flat foil unit is established for the top foil.Based on the model,the stiffness matrices of the bump foil and top foil of an actual bearing are established,and the DOF of the stiffness matrices are coupled to calculate the deformation of the foil under a specific load.A theoretical calculation model suitable for bump foil bearings is established according to the gas lubrication theory,the distribution of the bearing film pressure is calculated using the finite difference method.The pressure calculation is coupled to the aforementioned foil deformation calculation,aeroelastic coupling calculations were performed.The effect of different top foil thickness on bearing stiffness and the effect on foil deformation were analyzed,and the bearing characteristics of the bearing are analyzed.Experiment on the bearing properties of bump foil radial bearings is designed and carried out.The stiffness of static loading and unloading was tested.The displacement changes of different speeds of fixed load in motion state and the displacement of different loads at fixed speed were tested.The correctness of the theoretical calculation model is verified.