Research On Static Characteristics Of Double Bump Gas Foil Bearings Based On Contact Mechanics

The establishment of accurate and simple theoretical model is the basis of studying the performance of foil bearing.Although there are many modeling methods,how to consider the friction effect between foil is a difficult problem.Some scholars simplify the structure of the foil as a spring system or other models.Although the algorithm is simplified and the calculation time is saved,the characteristics of the foil structure cannot be studied in depth.There are few researches on double bump gas foil journal bearings,and there is no theoretical guidance in engineering application.Based on the above requirements,this paper uses the theory of contact mechanics to establish the model of foil structure and analyze its static characteristics.A new calculation method is proposed for the contact state and Coulomb friction between structures.The contact and separation between contact pairs are judged by Lagrange multiplier method,and the static or sliding state between structures is judged by penalty function method.The algorithm is simple and easy to implement.Compared with the simulation results of SOLIDWORKS and ANSYS,the accuracy of the model is verified.On this basis,the static loading and unloading and dynamic excitation processes of single-layer and double-layer bump foils are simulated respectively.The influences of Coulomb friction and external parameters on the stiffness and damping of the foil are analyzed.The results show that the double-layer bump foils have greater stiffness,but their energy consumption capacity is usually smaller than that of single-layer bump foils.Based on the study of the characteristics of the foil itself,the static characteristics of gas foil bearings,such as bearing capacity,deflection angle,minimum film thickness,are calculated when the rotor position is given.The results show that under the same eccentricity,the double bump gas foil bearings have greater bearing capacity,and their deflection angles are similar.Under light load,the minimum film thickness of the two is similar,while under heavy load,the minimum film thickness of double bump gas foil bearings is a little smaller.The static loading and unloading experiments of single-layer and double-layer foils are carried out,which are consistent with the theoretical calculation results.After the above research,it can provide performance prediction for the application of double bump gas foil bearings,and serve as the basis for the later research on complex structures such as interleaving flat foil and multi-layer bump foil.