Analysis Of The Nonlinear Inherent Characteristics Of The Bellows Diaphragm With Combined Structure

The thesis mainly studies the elastic element bellows in the dry gas sealing system,and introduces the development and use of the bellows at home and abroad.This paper uses the continuous method to divide the flat cone shell part and the circle The arc part is considered to be the initial deflection of the ring-shaped thin plate,and then based on the basic theory of nonlinear dynamics,the nonlinear dynamic control equation of the bellows diaphragm of the flat conical shell-circular-arc plate composite structure,the large deformation problem of the bellows diaphragm under the combined load was analyzed and calculated.At the same time,the nonlinear natural frequency problem of the combined structure bellows diaphragm under the dynamic and static loads was studied.Provide a basis for the practical application of the combined structure bellows diaphragm.Firstly,the development status and research significance of bellows in dry gas sealing system are introduced,different types of bellows are listed,and the main research methods of bellows materials at home and abroad are described.Secondly,on the basis of the nonlinear large deflection theory,the continuous method is used to analyze the nonlinear large deformation theory of the bellows diaphragm of the flat conical shell-circular-arc plate composite structure used in the dry gas sealing system.According to the modified iterative method,the nonlinear large deflection of the bellows diaphragm of the combined structure is solved,and at the same time,The non-linear bearing capacity of the diaphragm with the oblique edges of different inclined angles of the bellows flat conical shell part at the maximum deflection of the arc is analyzed by the second approximation,and on the basis of the same waveform,the bearing capacity of the diaphragm at the maximum deflection of the arc is analyzed,such as wave depth,arc radius and other parameters.Finally,the nonlinear natural frequency of the bellows diaphragm of the flat conical shell-circular-arc plate composite structure used in the dry gas sealing system is solved,and the mechanical model of the bellows diaphragm of the composite structure is established.Based on the theory of nonlinear large deformation of the bellows diaphragm,using the Hamiltonian principle,a series of equations for the combined structure bellows diaphragm is introduced,and then the perturbation variation method is used to solve the combined structure bellows diaphragm.,using first approximation,second approximation and third approximation,the nonlinearnatural frequency analytical value of the bellows diaphragm of combined structure is obtained.The characteristic relationship between natural frequency and load at different maximum amplitudes,vector height of bellows diaphragm,diaphragm inclination angle and arc wavelength is studied.