Axial propagation of flow-induced vibrations in thick walled pipes and hoses

This paper presents a numerical study in which the thick-wall assumption in a fluid-structure interaction analysis of liquid-filled pipes subjected to axial vibration is adopted. The influence of wall thickness on the dynamic characteristics of the system in the frequency domain is investigated and the validity of the thin-wall assumption is assessed for different scenarios. The analytical expressions are derived from the equations of motion in cylindrical coordinates and the mathematical model is compared with a 3D numerical model, developed via the finite element method. It is shown that a great range of industrial applications of pipe systems can be analyzed using a thin-wall assumption. However, for small pipe diameters such as those used in high precision machines, the wall thickness of a pipe becomes larger compared to its radius. For these scenarios, thin-walled pipe equations no longer hold since they are not able to predict stresses variation within the cross section of the pipe. Furthermore, this difference amplifies for soft wall materials.