Abstract:

In this study, a novel offset support design for enhancing the stability of fluid-conveying pipes is proposed. Specifically, by offsetting the simple support, the nonlinear stiffness in both tension and bending of the pipes is effectively increased. On the basis of the absolute nodal coordinate formulation (ANCF), a theoretical model for a pipe with an offset support under various boundary conditions is established and validated through experiments. A systematic investigation is subsequently conducted to explore the effects of the offset position and amplitude on the static deformation, stability, and nonlinear dynamic behaviors. The results indicate that the proposed offset support can significantly increase the stability of the fluid-conveying pipe and reduce its deformation amplitude. In most cases, a larger offset amplitude generally corresponds to a higher critical fluid velocity and a smaller deformation amplitude. With respect to the support position, placing an offset support at one-quarter of the span from the supported end can substantially improve the stability of simply supported pipes. With respect to cantilevered pipes, adding an offset support at the free end can considerably increase the critical flow velocity of the pipe. When the flow velocity is in the subcritical region, a pipe with an offset support maintains in-plane static deformation with a small amplitude. In the supercritical flow velocity region, compared with a pipe without an offset support, a pipe with an offset support has a smaller nonplanar configuration. This study provides new insight into enhancing the stability of fluid-conveying pipes via an offset support design, which features simple implementation and considerable application potential in engineering practice.

Key words: offset support, fluid-conveying pipe, buckling behavior, stability enhancement, critical fluid velocity