Research On Vibration Stability Of Rigid-flexible Coupling Pipe

In this paper,the stability of the rigid-flexible coupling pipe is studied,the dynamic model of the fluid-induced vibration of the coupled system of the elastic pipe and the rigid pipe is established,and the stability of the fluid-induced vibration of the coupled pipe system as well as the dynamic behavior and the relationship between parameters of system are analyzed.Through theoretical analysis and numerical calculation,the mechanism of the nonlinear dynamic system solution is proved,and the influence of the stiffness of the rotating coil spring,the mass ratio of the rigid tube and the elastic tube and the ratio of damping on the system and the critical flow rate of the system is revealed.In addition,this paper also studies the nonlinear dynamic behavior of the flow pipe under the initial axial load and distributed impact constraints,and that discovers some important nonlinear dynamic phenomena that have not been found before.It provides a new theoretical reference for establishing a coupled pipe dynamic model,exploring the instability mechanism and applying the solution method.the work of this paper has the following ways:First,In the design of the research plan,a new coupled flow pipe system is combined by the rigid flow pipe and the elastic flow pipe,and the nonlinear dynamic behavior of a similar cantilever pipe under the action of pulsating internal flow is studied.Some vibration phenomena that have not been revealed in the previous studies of the flow pipe were discovered.Second,In the application of the research method,the Galerkin method is applied to solve the coupled dynamics problem of the rigid pipe and the elastic pipe of the rigid-flexible coupled fluid pipe system,and the solution of the nonlinear dynamic system is obtained.Last,In the design of the research model,the system is modeled as a cubic nonlinear spring model and a modified trilinear spring model constraint,and the nonlinear dynamic behavior of the flow pipe under the initial axial load and distributed impact constraints is analyzed.The study found that under different initial pressure loads and cross-flow velocities,the pipe would lose its stability due to buckling and flutter.With the increase of the critical velocity and initial pressure load,the modified trilinear spring model appeared chaotic oscillations.Some new results obtained in the study of the impact force distribution of the impact system are helpful to understand and control the dynamic response of fluid conveying pipe.