Evaluation of gravity effects on the vibration of fluid-conveying pipes

Gravity effects are generally ignored in the study on the pipe vibration. However, in this paper, the effect of gravity on the nonlinear vibration of a pipe conveying fluid has been evaluated. The nonlinear vibration of the pipe with an intermediate elastic support is investigated, and the equilibrium configuration of the pipe caused by gravity is calculated. The governing equation of the nonlinear vibration near the equilibrium configuration is established. Then, the natural frequencies and modes of the transverse vibration of the pipe are obtained. The vibration characteristics of the pipe around the equilibrium configuration are studied. In addition, the effects of gravity on the vibration characteristics of the pipe are illustrated by comparing the same system without gravity effects considered. The influence of pipe parameters on the gravity effects is also investigated. The results show that there are some different trends in the natural frequencies with and without considering gravity effects. The lower-order natural frequencies are more affected by gravity. Moreover, the contribution of this paper is to propose an impact factor of gravity to evaluate the relative difference caused by gravity. Furthermore, the critical impact factors of the gravity of three metal pipes are proposed. In short, this paper evaluates the effects of gravity on the vibration of the pipe conveying fluid and provides an effective strategy for engineering design.