Random Uncertainty Modeling And Vibration Analysis Of Pipes Conveying Multi-phase Fluid

In the modern industry such as petroleum, chemical, nuclear power plant and marine engineering etc, pipes conveying multi-phase fluid, whose security is drawing more and more attention of the public, are widely used for the transmission of various fluidized materials. It is of great significance to study the vibration of pipes conveying multi-phase fluid to ensure its long-term stability and operation reliability for the national economic development and social stability. In this thesis the author studied the stochastic uncertainty modeling of pipes conveying multi-phase fluid by the Hamilton’s principle and stochastic nonlinear dynamics theory and analyzed the influence of system’s parameters on the dynamics of pipes. The main contributions are as follows:1. Based on Hamilton’s principle and stochastic nonlinear dynamics theory, the simulation of the uncertain stochastic excitation was given according to the complex conditon of pipes, and the random nonlinear vibration equations of the clamped-clamped pipe and the cantilevered pipe.2. The vibration responses of pipes conveying multi-phase fluid were solved by the Galerkin method and the generalized time integration algorithm, and a special Poincare map was adopted for the pipe’s vibration characteristic analysis.3. The dynamic characteristics of the clamped-clamped pipe and the cantilevered pipe were researched based on the vibration equations respectively, and the variation of the pipe’s natural frequencies and the vibration responses by the random excitation were studied. The influence of the system’s parameters, such as the excitation frequency, excitation intensity, spectral width, as well as the intensity and position of constraint, on pipe’s vibration were discussed in detail based on the phase trajectories and the Poincare map.4. According to the analysis of elastic restraint’s effect on the vibration response, some reasonable suggestions were given to choose its installation position and elasticity coefficient, which is helpful to reduce the vibration of such pipe to some degree.5. The dynamic model of the pipe was verified from the pipe vibration experiment by the comparison between the theoretical and the experimental modal analysis. Moreover, the influence of some critical parameters on the pipe’s vibration characteristics was analyzed based on the pipe’s vibration measurements in several various situations.