Fatigue performance evaluation of flexible riser joints using finite element method

Addressing the challenges of long-term reliance on imported products and the underdeveloped fatigue life evaluation system for flexible riser connectors in deepwater resource development, this study investigates a bonded flexible riser-floating platform system at a water depth of 1 200 m. A design and evaluation methodology for connectors based on multibody coupled dynamics and fatigue damage evolution mechanism is proposed. First, a coupled dynamic model of the platform and pipeline was established using OrcaFlex to extract time-history data for effective tension and bending moment at the pipe-end interface. Then, parametric finite element models of two connector types-hybrid and crimped-were developed, and their stress responses and fatigue damage were accurately simulated on the ANSYS platform. Finally, a fatigue life evaluation system accounting for multiaxial stress states was established by integrating the rainflow counting method with S-N curve theory. The results demonstrate that, compared to the crimped connector, the hybrid connector exhibits a 30% lower maximum stress level and a more uniform stress distribution, indicating superior structural synergy and fatigue resistance.