A Simplified Finite Element Model With Periodic Boundary Conditions for the Collapse Analysis of Flexible Pipes

Abstract With the expansion of offshore oil and gas exploration into ultra-deep water, the operational environment imposes significant challenges on the structural integrity of flexible pipes. Notably, the increased hydrostatic pressures place increased demands on the collapse resistance of flexible pipes, especially under bending conditions. However, predicting collapse loads in such scenarios is complex due to the intricate geometry and interlayer interactions within the flexible pipe structure. While full 3D finite element models provide detailed insights into the collapse behavior of bent flexible pipes, they are computationally intensive and impractical for routine engineering applications, necessitating a more efficient method. This study proposes a simplified finite element model that utilizes periodic boundary conditions to reduce model size and minimize computational demands. The model is applied to assess the anti-collapse performance of a 4-inch flexible pipe under different configurations, and its results are validated against full finite element simulations. The findings indicate that the simplified model effectively captures stress distributions and structural responses during bending and collapse, with critical load predictions closely aligning with those of full-scale models. The proposed simplified model significantly enhances computational efficiency, offering a practical and reliable approach for evaluating the collapse behavior of flexible pipes under bending conditions.