Research On Nonlinear Vibration Model And Simulation Of Fluid-conveying Pipes

Fluid-conveying pipes is applied in various fields, it is very prevalent that fluid-conveying pipes is destroyed because of shaking. This phenomenon takes a huge loss ,so people have paid more attentions to fluid-conveying pipes. At present, this is a hot research on shaking inside factors of pipe system besides outside factors. Especially,the research that nonlinear vibration of the fluid-conveying pipes with fluid structure interaction has been accepted widely. With the development of science and technology, in high-tech field, it is a key problem to decrease shaking and noises. It is the most important problem to the study of the root of inducing vibration. Therefore, it is practical significance and wide applied background to research on the vibration of the pipe's fluid structure interaction.Lateral displacement,axial displacement,fluid velocity and fluid pressure is variable in this article. Based on the theory of midline elongation,the total kinetic energy of fluid-conveying pipes system,the total potential energy of fluid-fulled pipe system and the total work of external force is calculated. Hamiltonian variation principle is applied to deduct in the axial motion and lateral motion equation of the fluid-conveying pipes. In modeling, in order to solve and simulate conveniently, Poisson coupling and Friction coupled is considered. Meanwhile, the effect of high-order small parameter on system,the part relocation parameters,coupling terms bewteen the pipe's axial and lateral is neglected.Axial and lateral motion equations are high partial differential equations, the analytical solutions of which are difficult to get, so this article takes finite element technique to gain numerical solutions. According to the characteristics of supported pipes conveying fluid simplify axial and lateral motion as two-node beam element model, the element standard equation is obtained through taking Lagrangian interpolation function and first-order Hermite interpolation function and implementing Ritz method, then merge to be whole transmission matrix equation. Adopting mode decompositiom and Newmark method to solve modal and response of the pipe by Matlab.In condition of four kinds of boundary restraint, such as fixed-fixed support, fixed-hinged support, fixed-stretched support and hinged-hinged support, modal and response of pipeline in axial and lateral motion are discussed in the article. The influence of pipeline span, fluid pressure, fluid velocity,fluid pressure disturbing and fluid speed disturbing on vibration property are analyzed emphasizely. As well as the influence of damping or not on natural frequency and vibration shape.are considered.The job of this paper lays a solid fundation for further research of complicated conduit system, and supplys some academic basis of vibration reduction for fluid-conveying pipes.