Abstract
This paper presents a modal analysis conducted under seabed dynamic pressure conditions. The polyethylene (PE) pipeline was approximated as a thin-walled long cylindrical shell. The impact of pressure on the pipeline structure was considered, the study investigated the circumferential dynamic characteristics. The natural characteristics of the structure were solved using the energy method. To validate the model, an experimental testing system was established to measure the natural frequencies of the polyethylene (PE) pipeline, capturing the first three natural frequencies and mode shapes of the structure. Additionally, we conduct a simulation analysis in COMSOL. The results showed that the discrepancies among the experimental, theoretical, and simulation results were within 6%, confirming the accuracy of the model. Building on this foundation, the simulation considered the impact of fluid-structure interaction on the natural frequencies of the cylindrical shell. Subsequently, the effects of pipe radius, pipe thickness, pipe length, variations in external load, and dimensionless parameters on the modal characteristics of the structure were further investigated. The comparison of simulation and theoretical results showed errors within 5%, further validating the reliability of the simulation outcomes.