Dynamic modeling and experimental verification of transverse vibration of hydraulic pipelines in subsea control system

In the subsea control system and the corresponding testing systems, the internal hydraulic pipelines experience a series of random vibrations. These vibrations may cause system fatigue, structural damage, or even failure. However, there is a paucity of research on the vibration response analysis of hydraulic pipelines inside the subsea control system and their test systems under random excitation. This study focuses on fixed-ended straight hydraulic pipelines applied in subsea control systems and their test benches. Such pipelines are prone to resonance-induced failure under random excitation. To address this issue, a targeted investigation is carried out on their transverse vibration characteristics, and a dynamic modeling method considering non-uniform flow is proposed. Firstly, a hydraulic pipeline system dynamic model considering non-uniform flow was established using Hamilton’s principle. The dynamic equations of the infusion pipeline based on Euler beams were derived. Then, the discontinuous Galerkin method is used to discretize the equation, and the discretized equation is solved using the modal method. Furthermore, the effectiveness of this method is verified through simulation and experiment. Finally, an in-depth analysis is conducted to explore the impacts of various factors. The findings demonstrate that the factors affecting the natural frequency, in descending order of influence, are: pipeline length, inner diameter, fluid velocity, and internal fluid pressure. The work can offer efficacious guidance for the design of hydraulic pipelines within subsea control systems and their testing systems.